JP2018096962A - Gas analyzing device and gas sampling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas analyzing device capable of accurately measuring concentration or amount of methane contained in a sample gas even when a pressure of a sample gas line changes.SOLUTION: A gas analyzing device 1 comprises: a sample gas line 11 through which a sample gas flows; a pressure drop mechanism 20 provided in the sample gas line 11; a pressure control mechanism 21 for controlling a difference in pressure of the sample gas line 11 between in front of and behind the pressure drop mechanism 20 by discharging a part of the sample gas from behind the pressure drop mechanism 20 or supplying a predetermined gas to behind the pressure drop mechanism 20, while referring to a pressure in front of the pressure drop mechanism 20; and an analyzer for analyzing the sample gas flowing through the sample gas line 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas analyzer that analyzes a component of a sample gas such as an automobile exhaust gas and a gas sampling device that collects the sample gas.

For example, as shown in Patent Document 1, when measuring methane contained in a sample gas such as exhaust gas, a non-methane cutter is allowed to pass and hydrocarbons other than methane contained in the sample gas are allowed to pass through the non-methane cutter. May burn.
During this combustion, it is necessary to supply oxygen to the sample gas at an appropriate ratio in order to prevent excessive oxygen and methane from burning too much, and oxygen from running out and hydrocarbons other than methane not burning. .

However, in such a gas analyzer, the flow rate of the sample gas may fluctuate due to, for example, the pulsation of the sampling pump or the pressure fluctuation of the introduced sample gas.
As a result, since the mixing ratio of sample gas and oxygen varies, there is a problem that the concentration and amount of methane to be measured vary.
Such a problem also arises in other gas analyzers other than those that measure methane.

Japanese Patent Laid-Open No. 08-035950

  The present invention has been made in view of the above problems, and provides a gas analyzer or gas sampling device that can maintain a constant flow rate of sample gas to be collected even if the pressure of the sample gas line fluctuates. It is the purpose.

  That is, the gas analyzer according to the present invention discharges a part of the sample gas from the sample gas line through which the sample gas flows, the pressure loss mechanism provided in the sample gas line, and the subsequent stage of the pressure loss mechanism. Or a pressure control mechanism that controls a pressure difference of the sample gas line before and after the pressure loss mechanism by supplying a predetermined gas to the subsequent stage of the pressure loss mechanism, and an analysis of the sample gas flowing through the sample gas line Analyzer.

According to such a gas analyzer, even if the pressure of the sample gas line fluctuates, the flow rate of the sample gas to be collected can be maintained constant, so that the components contained in the sample gas can be accurately detected. Can be analyzed.
In addition, for example, when mixing the sample gas with the operation gas or the dilution gas, the mixing ratio of the sample gas and the operation gas, the dilution gas, or the like can be maintained constant. Can be analyzed with high accuracy.

  As a specific embodiment, the pressure control mechanism includes a sample gas discharge line that partially discharges the sample gas from the sample gas line and a sample connected to the sample gas discharge line after the pressure loss mechanism. A sample pressure control unit that controls the pressure difference between the pressure of the sample gas line and the pressure of the sample pressure adjustment line in the previous stage of the pressure loss mechanism with reference to the pressure adjustment line and the pressure of the previous stage of the pressure loss mechanism The thing provided with.

  As another embodiment, the pressure control mechanism includes a gas supply line that supplies a predetermined gas to the sample gas line, and a pressure control valve provided in the gas supply line, after the pressure loss mechanism. And a differential pressure gauge that detects a pressure difference before and after the pressure loss mechanism, and the pressure control valve is controlled based on the pressure difference detected by the differential pressure gauge.

  As a more specific embodiment, the sample pressure control unit refers to the pressure at the front stage of the pressure loss mechanism, the pressure of the sample gas line at the front stage of the pressure loss mechanism, and the pressure of the sample pressure adjustment line And controlling the pressure of the sample pressure adjusting line so as to keep the pressure difference constant.

  More specifically, the pressure loss mechanism may be any one of a capillary, an orifice, and a back pressure valve.

  The gas analyzer refers to a first gas supply line that supplies the first gas downstream of the pressure loss mechanism in the sample gas line, and a pressure subsequent to the pressure loss mechanism in the sample gas line, The pressure of the sample gas line fluctuated if it further includes a first gas pressure regulating mechanism that maintains a constant difference between the supply side pressure of the first gas supply line and the pressure of the sample gas line. Even in this case, the flow rate of the supplied first gas can be kept constant, so that the mixing ratio of the sample gas and the first gas can be made constant.

  As a specific embodiment, the gas analyzer may further include an oxidation catalyst that removes hydrocarbon components other than methane from the sample gas in the subsequent stage of the discharge line.

  The gas analyzer refers to a second gas supply line that supplies a second gas downstream of the pressure loss mechanism in the sample gas line, and a pressure subsequent to the pressure loss mechanism in the sample gas line, If the pressure of the sample gas line fluctuates as long as it further includes a second gas pressure regulation mechanism that maintains a constant difference between the supply side pressure of the second gas supply line and the pressure of the sample gas line Even so, since the flow rate of the supplied second gas can be kept constant, the mixing ratio of the sample gas and the second gas can be made constant.

  The first gas is an oxygen-containing gas, the second gas is a hydrogen-containing gas, and the gas analyzer generates water by reacting the first gas and the second gas before the oxidation catalyst. If the water supply catalyst is further provided, water can be supplied to the oxidation catalyst, so that excessive combustion of the methane component in the sample gas can be prevented.

  If the supply amount of the first gas is larger than the amount that reacts with the second gas, oxygen necessary for the combustion of the non-methane component in the oxidation catalyst can be supplied, so that deterioration of the oxidation catalyst is suppressed. be able to.

  As described above, since the supply amount of the first gas is larger than the amount that reacts with the second gas, in the gas analyzer, due to the first gas remaining as a result of the reaction with the second gas, The sample gas is diluted.

  In the case where the gas analyzer further includes a suction type sampling pump disposed downstream of the measuring device on the sample gas line, the sample gas line is caused by the suction type sampling pump. Therefore, the effect of the present invention is particularly remarkably exhibited.

  As a specific embodiment of the gas analyzer, the sample gas is an exhaust gas discharged from a vehicle, and the gas analyzer is a vehicle-mounted gas analyzer.

  A sample gas line through which a sample gas flows, a pressure loss mechanism provided in the sample gas line, and a part of the sample gas is discharged from a subsequent stage of the pressure loss mechanism, or a predetermined stage is provided in a subsequent stage of the pressure loss mechanism By supplying gas, the effect of the present invention can also be achieved by a gas sampling device provided with a pressure control mechanism that controls the pressure difference of the sample gas line before and after the pressure loss mechanism.

  Further, a part of the sample gas is discharged from a sample gas line through which the sample gas flows, a pressure loss mechanism provided in the sample gas line, and a subsequent stage of the pressure loss mechanism, or a predetermined stage after the pressure loss mechanism. Gas analyzer comprising: a pressure control mechanism for controlling a pressure difference of the sample gas line before and after the pressure loss mechanism by supplying a gas; and an analyzer for analyzing the sample gas flowing through the sample gas line The same effect as that of the present invention can also be obtained by a method of sampling a sample gas using the.

According to the gas analyzer or gas sampling device of the present invention, the flow rate of the sample gas to be collected can be kept constant even when the pressure of the sample gas line fluctuates. Component can be analyzed with high accuracy.
In addition, for example, when mixing the sample gas with the operation gas or the dilution gas, the mixing ratio of the sample gas to the operation gas or the dilution gas can be made constant. It is possible to analyze with high accuracy.

The schematic diagram which shows the structure of the gas analyzer which concerns on 1st Embodiment of this invention. The schematic diagram which shows the structure of the gas analyzer which concerns on 2nd Embodiment of this invention. The figure for demonstrating the modification of the gas analyzer which concerns on the 2nd Embodiment of this invention. The schematic diagram for demonstrating the gas analyzer which concerns on other embodiment of this invention. The schematic diagram which shows the structure of the gas analyzer which concerns on other embodiment of this invention. The schematic diagram which shows the structure of the gas analyzer which concerns on other embodiment of this invention.

Below, 1st Embodiment of the gas analyzer 1 which concerns on this invention is described with reference to drawings.
The gas analyzer 1 according to the present embodiment analyzes a component contained in exhaust gas discharged from an internal combustion engine such as a vehicle engine, which is a sample gas, for example, as shown in FIG. The sample gas line 11 through which the sample gas flows, the methane analyzer 12 for analyzing methane contained in the sample gas, and the methane analyzer 12 for accurately analyzing methane in the sample gas A non-methane cutter 13 for removing non-methane components therein, a first gas supply line 14 for supplying a first gas containing oxygen necessary for removing the non-methane components to the non-methane cutter 13, and a first gas. A second gas containing hydrogen that reacts with oxygen and supplies moisture to the non-methane cutter 13 is supplied to the non-methane cutter 13. It is obtained by a 2 gas supply line 15.

Hereinafter, each part which comprises the said gas analyzer 1 is demonstrated. One end of the sample gas line 11 is connected to an exhaust pipe or the like for deriving exhaust gas from the vehicle engine or the like, and the other end is opened to the outside, for example. In the present embodiment, a suction-type sampling pump (not shown) that draws the sample gas into the sample gas line 11 is provided downstream of the methane analyzer 12 on the sample gas line, that is, downstream. .

In this embodiment, a flame ionization detector is used as the methane analyzer 12.

The non-methane cutter 13 burns (oxidizes) hydrocarbons other than methane in the sample gas flowing through the sample gas line 11 and contains, for example, manganese dioxide and copper oxide. is there.

The first gas supply line 14 supplies, for example, an oxygen-containing gas, which is a first gas, to the sample gas line 11, and one end of the first gas supply line 14 is connected to, for example, a cylinder (not shown) and the other end is connected to the sample gas line 11. The sample gas line 11 is connected upstream of the non-methane cutter 13, that is, upstream.

The second gas supply line 15 supplies the sample gas line 11 with a second gas, for example, a hydrogen-containing gas. One end of the second gas supply line 15 is connected to, for example, a cylinder (not shown) and the other end is connected to the sample gas line 11. The sample gas line 11 is connected upstream of the non-methane cutter 13.

In the present embodiment, the first gas supply line 14 and the second gas supply line 15 merge before the merge point with the sample gas line 11, and the inside of the first gas and the second gas is inside. A mixed line 16 that flows in a mixed manner is connected to the sample gas line 11. On the mixing line 16, a water supply catalyst 17 is provided that generates water by efficiently reacting oxygen in the first gas flowing through the mixing line 16 and hydrogen in the second gas.

In this embodiment, the total hydrocarbon analysis line 18 branched from the sample gas line 11 on the upstream side of the merge point with the mixing line 16 on the sample gas line 11 and the latter stage after the merge point. A non-methane cutter check line 19 is provided which branches from the sample gas line and joins the sample gas line 11 again at the front stage of the methane analyzer 12.

The total hydrocarbon analysis line 18 analyzes the total hydrocarbons contained in the sample gas, and the total hydrocarbon analysis line 18 analyzes the total hydrocarbons contained in the sample gas. A hydrogen analyzer 181 and a first flow rate controller 182 such as a capillary for controlling the flow rate of the sample gas flowing into the total hydrocarbon analysis line are provided. The capillary used in the present embodiment has an inner diameter that is narrower than the flow path before and after the capillary.

The non-methane cutter confirmation line 19 guides the sample gas to the methane analyzer 12 without passing through the non-methane cutter 13, and the non-methane cutter confirmation line 19 includes the sample gas. A second valve for switching the sample gas to flow through either the non-methane cutter check line 19 or the sample gas line 11 in cooperation with the first valve V1 provided at the rear stage of the non-methane cutter 13 of the line 11. A valve V2 is provided.

Therefore, the gas analyzer 1 according to the present embodiment has a pressure loss mechanism 20 that controls the flow rate of the sample gas flowing through the sample gas line 11 in addition to the above-described configuration, and before and after the pressure loss mechanism 20. The pressure control mechanism 21 for controlling the pressure difference of the sample gas line 11 to be constant, and the pressure difference between the pressure of the pressure loss mechanism 20 of the sample gas line 11 and the first gas supply line 14 are made constant. The first gas pressure adjusting mechanism 22 to be controlled, and the second gas pressure adjusting mechanism 23 for controlling the pressure difference between the pressure after the pressure loss mechanism 20 of the sample gas line 11 and the second gas supply line 15 to be constant. Are further provided.

  The pressure loss mechanism 20 is provided at a stage prior to the junction with the mixing line 16 on the sample gas line 11, and controls the flow rate of the sample gas flowing through the sample gas line 11. In this embodiment, for example, a capillary (first capillary 20) is used.

  The pressure control mechanism 21 maintains a constant pressure difference before and after the pressure loss mechanism 20 in the sample gas line 11 by controlling the pressure at the subsequent stage of the pressure loss mechanism 20. A sample pressure adjustment line 211 for discharging the flowing gas to the outside, a sample gas discharge line 212 for discharging a part of the gas flowing through the sample gas line 11 to the sample pressure adjustment line 211, and a flow through the sample pressure adjustment line 211 A second capillary 213 for controlling the gas flow rate, and a sample pressure control unit 214 for controlling the pressure of the sample pressure adjusting line 211 with reference to the pressure in the previous stage of the pressure loss mechanism 20 of the sample gas line 11; It has.

For example, one end of the sample pressure adjusting line 211 is connected to a cylinder (not shown), the other end is opened to the outside air, and a gas supplied from the cylinder or the like flows through the inside. A junction with the sample gas discharge line 212 is provided in the middle of the sample pressure adjustment line 211.

One end of the sample gas discharge line 212 is the latter stage of the pressure loss mechanism 20, specifically, immediately before the non-methane cutter 13 on the sample gas line and the second on the non-methane cutter confirmation line 19. The other end of the valve is connected to the sample pressure adjusting line 211.

The second capillary 213 is provided at a stage subsequent to a connection point with the sample gas discharge line 212 on the sample pressure adjustment line 211.

The sample pressure control unit 214 controls the flow rate of the sample gas flowing into the sample gas discharge line 212 from the sample gas line 11 or the non-methane cutter confirmation line 19. In this embodiment, the sample pressure control unit 214 controls the sample gas flow rate. This is a sample pressure adjusting valve 214V provided on the upstream side of the connection point with the sample gas discharge line 212 on the pressure adjusting line 211.

More specifically, the sample pressure adjusting valve 214V directly senses the pressure in the front stage of the pressure loss mechanism 20 of the sample gas line 11 and changes the degree of opening and closing of the valve. The flow rate of the gas flowing through the line 211 is adjusted to control the pressure in the stage before the second capillary 213 in the sample pressure adjustment line 211.

The first gas pressure regulating mechanism 22 includes a third capillary 221 provided on the first gas supply line 14 and a first gas pressure regulating valve 222 provided on the upstream side of the third capillary 221. It is a thing. The third capillary 221 controls the flow rate of the first gas flowing through the first gas supply line 14, and causes pressure loss in the first gas supply line 14.

The first gas pressure regulating valve 222 controls the pressure difference of the first gas supply line 14 before and after the third capillary 221 at a constant level. For example, the first gas pressure regulating valve 222 is a rear stage of the moisture supply catalyst 17 on the mixing line 16. By directly sensing the pressure of the first capillary, the degree of opening and closing of the valve changes, and the flow rate of the first gas upstream of the third capillary 221 is controlled, so that the first gas supply line, that is, the first stage of the third capillary 221 is controlled. 14 controls the pressure on the supply side.

The second gas pressure adjusting mechanism 23 includes a fourth capillary 231 provided on the second gas supply line 15 and a second gas pressure adjusting valve 232 provided upstream of the fourth capillary 231. It is a thing. The fourth capillary 231 controls the flow rate of the second gas flowing through the second gas supply line 15, and causes pressure loss in the second gas supply line 15.

The second gas pressure regulating valve 232 controls the pressure difference of the second gas supply line 15 before and after the fourth capillary 231 to be constant. For example, the second gas pressure regulating valve 232 is a rear stage of the moisture supply catalyst 17 on the mixing line 16. By directly sensing the pressure of the valve, the degree of opening and closing of the valve changes, and the flow rate of the second gas upstream of the fourth capillary 231 is controlled, so that the previous stage of the fourth capillary 231, that is, the second gas supply line. 15 for controlling the pressure on the supply side.

Next, the operation of the gas analyzer 1 according to this embodiment will be described.
First, the sample gas is drawn into the sample gas line 11 from an exhaust pipe connected to a vehicle engine or the like, for example, by the sampling pump.
At this time, if necessary, a filter indicated by F in the drawing, a capillary for controlling the flow rate, or the like may be appropriately provided.

  Since the flow rate of the sample gas flowing into the sample gas line 11 is controlled by the first capillary 20 and the first flow rate control device 182, surplus exceeding the flow rates of the first capillary 20 and the first flow rate control device 182. The sample gas is discharged outside without entering the sample gas line 11.

At this time, the sample pressure adjusting valve 214 </ b> V directly monitors the pressure in the previous stage of the pressure loss mechanism 20 in the sample gas line 11.
For example, when the pressure upstream of the pressure loss mechanism 20 in the sample gas line 11 increases, the sample pressure adjustment valve 214V increases the amount of gas flowing through the sample pressure adjustment line 211 to increase the sample pressure. The pressure between the regulating valve 214V and the second capillary 213 is increased.
As a result, the pressure difference between the pressure of the sample gas discharge line 212 connected to the sample pressure adjusting line 211 and the sample gas line 11 becomes small, and the sample gas line 11 or the non-methane cutter is used for confirmation. Since the amount of gas flowing from the line 19 to the sample gas discharge line 212 decreases, the pressure after the pressure loss mechanism 20 in the sample gas line 11 increases.

On the other hand, when the pressure before the pressure loss mechanism 20 in the sample gas line 11 decreases, the sample pressure adjustment valve 214V reduces the amount of gas flowing through the sample pressure adjustment line 211 to adjust the sample pressure. The pressure between the valve 214V and the second capillary 213 is reduced.
As a result, the pressure difference between the pressure of the sample gas discharge line 212 connected to the sample pressure adjustment line 211 and the sample gas line 11 becomes large, and the sample gas line 11 or the non-methane cutter is used for confirmation. Since the amount of gas flowing from the line 19 to the sample gas discharge line 212 increases, the pressure after the pressure loss mechanism 20 of the sample gas line 11 decreases.

  In this way, the sample pressure adjusting valve 214V always maintains the pressure at the front stage and the rear stage of the pressure loss mechanism 20 of the sample gas line 11 constant, and the sample gas passing through the first capillary 20 is kept constant. Keep the flow rate constant.

The sample gas that has passed through the first capillary 20 merges with the first gas and the second gas supplied to the sample gas line 11 through the mixing line 16.
At this time, the first gas pressure regulating valve 222 and the second gas pressure regulating valve 232 are pressures after the pressure loss mechanism 20 of the sample gas line 11, for example, the moisture supply catalyst 17 of the mixing line 16. The downstream pressure is directly monitored.

For example, when the pressure after the water supply catalyst 17 in the mixing line 16 increases, the first gas pressure regulating valve 222 and the second gas pressure regulating valve 232 increase the flow rate of the gas flowing through each pressure regulating valve.
As a result, the pressure between the first gas pressure regulating valve 222 and the third capillary 221 in the first gas supply line 14, and the second gas pressure regulating valve 232 and the fourth capillary in the second gas supply line 15. The pressure between the two increases.

On the other hand, when the downstream pressure of the water supply catalyst 17 in the mixing line 16 decreases, the flow rate of the gas that the first gas pressure regulating valve 222 and the second gas pressure regulating valve 232 flow through the pressure regulating valves 222 and 232, respectively. Reduce.
As a result, the pressure between the first gas pressure regulating valve 222 and the third capillary 221 in the first gas supply line 14, and the second gas pressure regulating valve 232 and the fourth gas pressure in the first gas supply line 14. The pressure between the capillaries 231 decreases.

  In this way, the first gas pressure regulating valve 222 and the second gas pressure regulating valve 232 are arranged so that the pressure after the pressure loss mechanism 20 of the sample gas line 11 and the pressure before the third capillary 221 or the fourth capillary 231 are obtained. The pressure is always kept constant, and the flow rates of the first gas and the second gas supplied to the sample gas line 11 are kept constant.

  At this time, for example, it is preferable that the amount of oxygen contained in the first gas is always set larger than the amount of oxygen that reacts with hydrogen in the water supply catalyst 17 to become water. That is, the gas supplied from the mixing line 16 to the sample gas line 11 is preferably a gas containing water and oxygen.

  In this way, the sample gas diluted by merging with the gas containing water and oxygen supplied to the sample gas line 11 by the mixed gas line passes through the non-methane cutter 13, and if necessary. The flow rate is appropriately controlled and the methane analyzer 12 guides and analyzes the flow.

  According to the gas analyzer 1 configured as described above, for example, the pressure of the sample gas fed into the sample gas line 11 fluctuates due to the pulsation of the sampling pump or a change in the operating state of the engine due to an accelerator or a brake. Even in this case, the pressure difference between the pressure loss mechanism 20 and the pressure loss mechanism 20 can be kept constant, and the amount of the sample gas passing through the pressure loss mechanism 20 can always be kept constant.

  Since the pressure after the pressure loss mechanism 20 of the sample gas line 11 is adjusted with reference to the pressure before the pressure loss mechanism 20 of the sample gas line 11, for example, by accelerator or brake operation, By changing the state of the engine of the vehicle, the amount of the sample gas passing through the pressure loss mechanism 20 is always kept constant even when the pressure on the inlet side of the sample gas rapidly changes. Can do.

  Further, even when the pressure of the sample gas line 11 fluctuates, the pressure difference between the pressure loss mechanism 20 in the sample gas line 11 and the pressure difference in the previous stage of the third capillary 221 and the fourth capillary 231 respectively. Since it is kept constant, the flow rates of the first gas and the second gas supplied to the sample gas line 11 can always be kept constant.

As a result, the mixing ratio of the sample gas that merges at the rear stage of the pressure loss mechanism 20 of the sample gas line 11 and the first gas and the second gas can be always constant.
As a result, the dilution rate of the sample gas with the first gas and the second gas is stabilized, and the concentration and amount of methane contained in the sample gas can be accurately measured.

  The sample gas discharge line 212 is connected to the sample gas line 11 immediately before the non-methane cutter 13 of the sample gas line 11, and the gas discharged from the sample gas discharge line 212 is the sample gas and the sample gas. Since the first gas and the second gas are mixed and mixed, the mixing ratio between the sample gas, the first gas, and the second gas is unlikely to fluctuate.

  By the way, in order to accurately analyze the methane component contained in the sample gas by the gas analyzer 1, the non-methane cutter 13 burns only hydrocarbons other than methane in the sample gas to separate methane. There is a need to.

When non-methane cutter 13 burns hydrocarbons other than methane, hydrocarbons other than methane may not burn if oxygen is insufficient. Therefore, if oxygen is supplied in excess, methane may burn too much.
Therefore, it can be considered that water is supplied to the non-methane cutter 13 to suppress the combustion of methane.

In this regard, in the present embodiment, the amount of the oxygen-containing gas that is the first gas supplied to the moisture supply catalyst 17 is greater than the amount of the hydrogen-containing gas that is the second gas. A water-containing gas containing oxygen-containing gas as the first gas and water generated by the moisture supply catalyst 17 is supplied.
Therefore, even if the pressure of the sample gas fluctuates, an appropriate amount of oxygen and water can be stably supplied to the non-methane cutter 13, so that the separation performance of the non-methane cutter 13 is adjusted to an appropriate range. can do.

  Next, a second embodiment of the gas analyzer 1 according to the present invention will be described with reference to the drawings.

  In the first embodiment, the pressure control mechanism 21 is configured to discharge a part of the sample gas from the subsequent stage of the pressure loss mechanism 20, but in the second embodiment, as shown in FIG. However, the predetermined gas is supplied to the subsequent stage of the pressure loss mechanism 20. Hereinafter, the configuration of the pressure control mechanism 21 of the second embodiment will be described in detail.

  The pressure control mechanism 21 keeps the pressure difference before and after the pressure loss mechanism 20 constant by controlling the pressure after the pressure loss mechanism 20. Specifically, as shown in FIG. 2, the pressure control mechanism 21 is provided in a third gas supply line L and a third gas supply line L that supply a predetermined third gas from the outside to the subsequent stage of the pressure loss mechanism 20. A pressure control valve LV, and a control device C for controlling the valve opening degree of the pressure control valve LV.

The third gas supply line L supplies, for example, the atmospheric air taken in via the filter F to the downstream side of the pressure loss mechanism 20 as the third gas. The third gas may be any gas that does not interfere with the analysis of the sample gas by the methane analyzer 12 or the total hydrocarbon analyzer 181. For example, the sample gas itself may be the first gas or the second gas of the first embodiment. Other gases may be used.
The third gas supply line L is connected to an exhaust line RL provided with a sampling pump (not shown). A buffer tank BT is provided in the exhaust line RL.

  The pressure control valve LV is provided in the third gas supply line L and controls the flow rate of the third gas, and is specifically an electromagnetic valve such as a linear valve.

  The control device C is a computer including a CPU, a memory, an A / D converter, and the like, and the pressure control valve LV is opened by cooperation of the CPU and peripheral devices according to a program stored in a predetermined area of the memory. Configured to control the degree.

  Here, a differential pressure gauge DPS for detecting a pressure difference before and after the pressure loss mechanism 20 is provided, and the pressure difference detected by the differential pressure gauge DPS is sequentially transmitted to the control device C as a differential pressure signal. . Specifically, the differential pressure gauge DPS detects a pressure difference between the pressure upstream of the pressure loss mechanism 20 and the pressure downstream of the pressure loss mechanism 20 and upstream of the analyzers 12 and 181.

  And the control apparatus C controls the linear valve which is the pressure control part LV mentioned above based on the pressure difference which a differential pressure signal shows. Specifically, the control device C performs feedback control on the valve opening degree of the pressure control unit LV so that the pressure difference indicated by the differential pressure signal matches a preset target value.

  According to the gas analyzer 1 configured as described above, even when the pressure of the sample gas fed into the sample gas line 11 fluctuates due to the pulsation of the sampling pump or the change in the operating state of the engine due to the accelerator or the brake. The pressure control mechanism 21 keeps the pressure difference before and after the pressure loss mechanism 20 (that is, the pressure difference between the upstream of the pressure loss mechanism 20 and the confluence of the sample gas line 11 and the third gas supply line L) constant. be able to. Thereby, the flow rate of the sample gas passing through the force loss mechanism 20 can be kept constant, and the flow rate of the sample gas flowing through the methane analyzer 12 and the total hydrocarbon analyzer 181 can be made constant.

  Further, since the pressure control mechanism 21 supplies the atmosphere as the third gas to the subsequent stage of the pressure loss mechanism 20 so that the pressure difference before and after the pressure loss mechanism 20 is constant, the sample gas is supplied with a desired dilution rate. The measurement accuracy of the methane analyzer 12 and the total hydrocarbon analyzer 181 can be improved.

In the above-described embodiment, the pressure control unit LV is digitally controlled by the control device C. However, the pressure control unit LV may be controlled in an analog manner based on the detection value of the differential pressure sensor DPS.
Specifically, as shown in FIG. 3, a voltage indicating a detected value of the differential pressure sensor DPS and a voltage indicating a preset target value are input to an analog computing unit, and an output voltage based on the difference between these voltages is input. The structure which controls the valve opening degree of the pressure control valve LV by outputting to the pressure control part LV is mentioned.

  By the way, in the first embodiment and the second embodiment, as another difference, in the second embodiment, a differential pressure gauge DPS is provided, and the linear valve is based on the pressure difference detected by the differential pressure gauge PDS. There is a point which controls LV. Hereinafter, this point will be described.

  First, as shown in FIG. 4, in a configuration in which the exhaust gas sampled by the sampling pump P is analyzed by an analyzer A such as a methane analyzer or a total hydrocarbon analyzer, the pressure regulating valve V is a mechanical type such as a diaphragm type. Consider the case of a pressure regulating valve.

  In the configuration described above, in order to control the exhaust gas flow rate flowing through the analyzer A to a constant flow rate, the pressure regulating valve V may be controlled so that the pressure difference before and after the pressure loss mechanism Z such as a capillary is kept constant. .

  However, if the pressure regulating valve V is a mechanical pressure regulating valve, a response delay due to a flow rate fluctuation (pulsation) or a change in atmospheric pressure of the sampling pump P, a diaphragm hardening due to a change in ambient temperature, or the like occurs. Thus, in the configuration using the mechanical pressure regulating valve, the pressure difference before and after the pressure loss mechanism Z cannot be kept constant with a desired accuracy due to various physical factors and changes in the surrounding environment. As a result, the indication value of the analyzer A is affected, and there arises a problem that the analysis accuracy cannot be ensured.

  Therefore, the present inventor has conceived the configuration shown in FIG. 5 in order to solve the above-described problem. That is, in this configuration, a differential valve that detects a pressure difference before and after the pressure loss mechanism Z while providing a linear valve LV in a gas supply line L that supplies a predetermined gas (here, air) to the subsequent stage of the pressure loss mechanism 20. A DPS is provided, and the valve opening degree of the linear valve LV is controlled so that the detected value of the differential pressure gauge DPS is constant.

With such a configuration, since the linear valve LV is controlled based on the detection value of the differential pressure gauge DPS, the influence of the surrounding environment such as the ambient temperature and the atmospheric pressure can be extremely reduced, and the pressure loss mechanism Z It is possible to keep the pressure difference between the front and rear constant with desired accuracy.
Furthermore, since the linear valve LV is controlled based on the pressure difference based on the detected value of the differential pressure gauge DPS, the responsiveness can be increased compared to the configuration shown in FIG. 4, and the flow rate fluctuation (pulsation) of the pump P is reduced. Even if it occurs, the influence of the flow rate fluctuation on the indicated value of the analyzer A becomes extremely small, and the analysis accuracy of the analyzer A can be ensured.

Such effects can also be achieved by the gas analyzer 1 of the second embodiment.
That is, in the second embodiment, since the pressure control mechanism 21 controls the pressure difference before and after the pressure loss mechanism 20 based on the detected value of the differential pressure gauge DPS, the influence of the ambient temperature such as the ambient temperature and the atmospheric pressure is extremely small. Even if flow rate fluctuations (pulsations) of the sampling pump occur, the influence on the indicated values of the analyzers 12 and 181 can be made extremely small.
In addition, if the influence of fluctuations in the flow rate of the sampling pump can be sufficiently reduced, the buffer tank BT can be eliminated, and the apparatus can be downsized.

The present invention is not limited to the above embodiments.
For example, a gas sampling device may be provided that includes the sample gas line 11, the pressure loss mechanism 20, and the pressure control mechanism 21.

The pressure control mechanism 21 may supply a predetermined gas to the subsequent stage of the pressure loss mechanism 20 of the sample gas line 11.
The predetermined gas may be any gas as long as it does not interfere with the analysis of the sample gas by the methane analyzer 12, and may be, for example, the sample gas itself, the first gas, the second gas, or another gas.

  The sample pressure adjusting valve 214V is not limited to directly sensing the pressure of the sample gas line 11 before the pressure loss mechanism 20, but is a pressure sensor arranged at the front of the pressure loss mechanism 20 on the sample gas line 11. The pressure measured by the above may be output to an information processing circuit (not shown), and the information processing circuit may output a command signal to the sample pressure adjusting valve 214V to adjust the degree of opening and closing. The information processing circuit includes a CPU, a memory, a communication port, an A / D converter, and the like, and may be dedicated to the gas analyzer 1 or a general-purpose computer.

  Similarly, the first gas pressure regulating valve 222 and the second gas pressure regulating valve 232 are not limited to directly sensing the pressure of the mixing line 16 but are measured by a pressure sensor or the like disposed on the mixing line 16. Pressure is output to the information processing circuit, and the information processing circuit outputs a command signal to each of the first gas pressure regulating valve 222 and the second gas pressure regulating valve 232 to adjust the degree of opening and closing of these valves. It may be a thing.

  The water supply catalyst 17 improves the reaction efficiency of oxygen and hydrogen in the mixing line 16, and the oxygen and hydrogen mixed in the mixing line 16 are in the case where the water supply catalyst 17 is not present. However, the water supply catalyst 17 is not an essential component for the gas analyzer 1 because it can react naturally to produce water. Therefore, the gas analyzer 1 does not necessarily have to include the moisture supply catalyst 17.

The first gas supply line 14 and the second gas supply line 15 may not be merged and may be independently connected to the sample gas line 11.
For example, as shown in FIG. 6, the gas analyzer 1 may directly supply water or a water-containing gas containing water as the second gas from the outside.

  Furthermore, the water-containing gas directly supplied from the outside may be the first gas, and the first gas may contain a predetermined amount of oxygen.

The oxygen-containing gas may be composed only of oxygen or a mixed gas containing oxygen at a predetermined concentration, for example, the atmosphere.
Similarly, the hydrogen-containing gas may be composed of only hydrogen or a mixed gas containing hydrogen at a predetermined concentration.
The first gas and the second gas are not limited to those containing oxygen, hydrogen, or water, and may be nitrogen-containing gas, helium-containing gas, or various other types of gases depending on the purpose of analysis. good.

  The sampling pump is not limited to the one disposed at the subsequent stage of the methane analyzer 12, and may be disposed before the pressure loss mechanism 20.

  The gas analyzer 1 according to the present invention is not limited to a device that is mounted on a vehicle or the like and analyzes exhaust gas of the vehicle or the like, but may be a device installed in a laboratory or the like to analyze the exhaust gas of a vehicle or the like. In addition to exhaust gas, a wide range of sample gas components such as environmental gas may be analyzed.

Further, the component to be analyzed is not limited to methane, and other components such as components containing all hydrocarbons, nitrogen, oxygen, hydrogen, carbon, sulfur, etc. may be analyzed.
The analyzer is not limited to the flame ionization detector, but a non-dispersive infrared absorption method, a chemiluminescence method, a magnetic pressure method, a zirconia method, an FTIR, a mid-infrared laser spectroscopy, a gas chromatograph for analyzing sample gas components. Various types of analyzers using a method, a liquid chromatographic method, or the like, or a combination thereof can be used.

A fifth capillary 24 for controlling the flow rate of the gas flowing through the non-methane cutter 13 may be provided after the connection point between the sample gas line 11 and the sample gas discharge line 212 and before the non-methane cutter 13. good.
Further, a sixth capillary 25 for controlling the flow rate of the gas flowing through the non-methane cutter confirmation line 19 may be provided before the second valve 191 of the non-methane cutter confirmation line 19.
At this time, the flow rate of the gas passing through the fifth capillary 24 or the sixth capillary 25 is set to the flow rate of the sample gas passing through the first capillary 20 and the first gas flowing into the sample gas line 11 from the mixing line 16. By setting the flow rate to be smaller than the total flow rate of the gas and the second gas, the backflow of the sample gas from the sample gas discharge line 212 to the sample gas line 11 can be prevented.

The pressure loss mechanism 20 only needs to cause a pressure loss in the sample gas line 11. In the above-described embodiment, a capillary is used, but an orifice, a back pressure valve, or the like may be used.
Each of the second to sixth capillaries and the first flow rate control device 182 is not limited to a capillary but may be an orifice, a back pressure valve, or the like.
In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

Gas analyzer ・ ・ ・ 1
Sample gas line ... 11
Methane analyzer ... 12
Non-methane cutter ... 13
First gas supply line ... 14
Second gas supply line ... 15
Moisture supply catalyst ... 17
Pressure loss mechanism ... 20
Pressure control mechanism 21
Sample pressure adjustment line 211
Sample gas discharge line ... 212
Sample pressure controller 214
First gas pressure adjusting mechanism 22
Second gas pressure adjusting mechanism 23

Claims (16)

A sample gas line through which the sample gas flows;
A pressure loss mechanism provided in the sample gas line;
By discharging a part of the sample gas from the subsequent stage of the pressure loss mechanism or supplying a predetermined gas to the subsequent stage of the pressure loss mechanism, the pressure difference of the sample gas line before and after the pressure loss mechanism is reduced. A pressure control mechanism to control,
A gas analyzer comprising: an analyzer for analyzing the sample gas flowing through the sample gas line. The pressure control mechanism includes:
A sample gas discharge line for partially discharging the sample gas from the sample gas line at a subsequent stage of the pressure loss mechanism;
A sample pressure adjustment line connected to the sample gas discharge line;
A sample pressure control unit that controls a pressure difference between the pressure of the sample gas line and the pressure of the sample pressure adjustment line in the previous stage of the pressure loss mechanism with reference to the pressure in the previous stage of the pressure loss mechanism. Item 4. The gas analyzer according to Item 1. The pressure control mechanism includes:
A gas supply line for supplying a predetermined gas to the sample gas line at a subsequent stage of the pressure loss mechanism;
A pressure control valve provided in the gas supply line;
A differential pressure gauge for detecting a pressure difference before and after the pressure loss mechanism,
The gas analyzer according to claim 1, wherein the pressure control valve is controlled based on a pressure difference detected by the differential pressure gauge.   The gas analyzer according to any one of claims 1 to 3, wherein the pressure loss mechanism is any one of a capillary, an orifice, and a back pressure valve. A first gas supply line for supplying the first gas downstream of the pressure loss mechanism in the sample gas line;
A first gas pressure adjusting mechanism that maintains a constant difference between the pressure on the supply side of the first gas supply line and the pressure on the sample gas line with reference to the pressure after the pressure loss mechanism in the sample gas line; The gas analyzer according to any one of claims 1 to 4, further comprising:   The non-methane cutter which removes hydrocarbon components other than methane from the sample gas is further provided between the pressure loss mechanism on the sample gas line and the analyzer. The gas analyzer described in 1. A second gas supply line for supplying a second gas downstream of the pressure loss mechanism in the sample gas line;
A second gas pressure regulating mechanism that maintains a constant difference between the pressure on the supply side of the second gas supply line and the pressure on the sample gas line with reference to the pressure after the pressure loss mechanism in the sample gas line The gas analyzer according to any one of claims 1 to 6, further comprising: The first gas is oxygen, the second gas is hydrogen;
The gas analyzer according to claim 6 or 7, further comprising a moisture supply catalyst that generates water by reacting the first gas and the second gas before the non-methane cutter.   The gas analyzer according to claim 8, wherein a supply amount of the first gas is a supply amount larger than an amount reacting with the second gas.   The gas analyzer according to claim 8 or 9, wherein the sample gas is diluted with the first gas remaining as a result of the reaction with the second gas.   The gas analyzer according to any one of claims 8 to 10, wherein the sample gas discharge line partially discharges the sample gas diluted with the first gas from a stage after the water supply catalyst. .   The gas analyzer according to any one of claims 1 to 11, wherein the gas analyzer further comprises a suction type sampling pump disposed downstream of an analyzer on the sample gas line.   The gas analyzer according to any one of claims 1 to 12, wherein the sample gas is an exhaust gas discharged from an internal combustion engine. The sample gas is exhaust gas discharged from a vehicle,
The gas analyzer according to any one of claims 1 to 13, wherein the gas analyzer is a vehicle-mounted gas analyzer. A sample gas line through which the sample gas flows;
A pressure loss mechanism provided in the sample gas line;
By discharging a part of the sample gas from the subsequent stage of the pressure loss mechanism or supplying a predetermined gas to the subsequent stage of the pressure loss mechanism, the pressure difference of the sample gas line before and after the pressure loss mechanism is reduced. A gas sampling device comprising a pressure control mechanism for controlling. A sample gas line through which the sample gas flows;
A pressure loss mechanism provided in the sample gas line;
By discharging a part of the sample gas from the subsequent stage of the pressure loss mechanism or supplying a predetermined gas to the subsequent stage of the pressure loss mechanism, the pressure difference of the sample gas line before and after the pressure loss mechanism is reduced. A pressure control mechanism to control,
The gas sampling method using the gas analyzer provided with the analyzer which analyzes the sample gas which flows through the said sample gas line.