JP4046650B2 - Continuous fluid separation and analysis method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous fluid separation / analysis method and apparatus capable of continuously separating, analyzing, and measuring only a specific component from a fluid mixture containing many components, such as automobile exhaust gas. It is.
[0002]
[Prior art]
In automotive exhaust gas component analysis, it is necessary to determine the amount of methane and total hydrocarbons (THC) in exhaust gas in order to comply with NMOG (hydrocarbons other than methane and oxygen-containing organic compounds) regulations. is there. Conventionally, FID (hydrogen flame ionization detector) and FTIR (Fourier transform) have been used as measurement devices to quantitatively measure specific components such as methane from a mixed gas containing many components such as automobile exhaust gas. Infrared spectrometers) were commonly used. In these measurements, exhaust gas diluted with air is collected in a gas collection container such as a tetra bag, and quantitative measurement of methane is performed by batch processing.
[0003]
There is also a method of continuously measuring methane by FID or NDIR (non-dispersive infrared spectroscopy) gas analysis after burning only NMOG from the exhaust gas THC by a selective combustion type heating catalyst.
[0004]
[Problems to be solved by the invention]
In the conventional quantitative measurement of methane by batch processing, there is a problem that continuous measurement such as continuous measurement of changes in the amount of methane in exhaust gas cannot be performed. In addition, since the exhaust gas is diluted with air and measured, the concentration of methane in the exhaust gas becomes thin and the measurement error increases. This is because the concentration of methane in the exhaust gas is reduced due to exhaust gas regulations, and the methane originally contained in the air is mixed, so that the measurement error is further increased.
[0005]
In the method of measuring methane after burning only NMOG from the exhaust gas THC, when NMOG alone is burned, methane is also partially burned (about 20%), which leads to an increase in measurement error. There was a problem. This has been an inevitable problem even when combined with a highly selective NDIR gas analysis method.
[0006]
Accordingly, the present invention provides a continuous fluid separation / selection / analysis / measurement capable of continuously separating / analyzing / measuring only a specific target component such as methane from a mixed fluid containing many components such as automobile exhaust gas. An object is to provide an analysis method and apparatus.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the continuous fluid separation method of the present invention includes a plurality of columns in which the retention time of the target component fluid is substantially the same and the retention time of the unnecessary component fluid is larger than the retention time of the target component fluid; A continuous fluid separation method using an output flow path for outputting a target component fluid, a procedure for starting the flow of the sample fluid to each of the columns at a predetermined timing, and a target component fluid from each of the columns And a procedure for switching so that only the fluid flowing out from the column is output from the output flow channel during the time period when only the fluid flows out.
[0008]
Further, the continuous fluid analysis method of the present invention detects a target component fluid and a plurality of columns in which the retention time of the target component fluid is substantially the same and the retention time of the unnecessary component fluid is longer than the retention time of the target component fluid. A continuous fluid analysis method using a detection means, in which a flow of the sample fluid starts at a predetermined timing with respect to each of the columns, and a time zone in which only the target component fluid flows out of the columns. And a procedure for switching so that only the fluid flowing out from the column is supplied to the detection means, and a procedure for continuously measuring the target component fluid by the detection means.
[0009]
The continuous fluid separation device of the present invention outputs the target component fluid and a plurality of columns having the same retention time of the target component fluid and the retention time of the unnecessary component fluid being longer than the retention time of the target component fluid. An output flow path, an inflow side selection means provided on the inflow side of the plurality of columns and selectively allowing the sample fluid to flow into at least one of the plurality of columns; and provided on the outflow side of the plurality of columns. Controlling the outflow side selection means for selecting the sample fluid flowing out from the plurality of columns and outputting it to the output flow path, the inflow side selection means and the outflow side selection means, And a control means for continuously outputting only the target component fluid from the output flow path.
[0010]
The continuous fluid analyzer of the present invention detects a target component fluid and a plurality of columns that have substantially the same retention time of the target component fluid and have a retention time of the unnecessary component fluid that is longer than the retention time of the target component fluid. Provided on the inflow side of the plurality of columns, and provided on the outflow side of the plurality of columns, the inflow side selection means for selectively flowing the sample fluid into at least one of the plurality of columns, Controlling outflow side selection means for selecting the sample fluid flowing out from the plurality of columns and supplying the sample fluid to the detection means, the inflow side selection means, and the outflow side selection means to control the target component in the sample fluid Control means for continuously supplying only the fluid to the detection means.
[0011]
Further, in the above continuous fluid analyzer, the inflow side selecting means switches between a state in which the sample fluid flows into the column in the forward direction and a state in which the cleaning fluid flows into the column in the reverse direction. It is preferable that
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of a continuous gas analyzer of the present invention. This continuous gas analyzer selects and analyzes and measures only a specific target component from a sample gas containing a plurality of components, such as automobile exhaust gas. Here, methane will be described as an example of the target component. Examples of unnecessary components include ethane. This continuous gas analyzer has n columns from the first column 11 to the nth column 1n.
[0013]
These columns have different moving speeds of the target component and the unnecessary component in the column, and the retention time of the target component is shorter than the retention time of the unnecessary component. Here, the time from the start of flow into the column to the start of flow is defined as the holding time. That is, when the target component and the unnecessary component are allowed to flow into the column at the same time, the target component flows out earlier, and the unnecessary component flows out after a predetermined time from the target component. Assuming that the retention time of the target component is t and the retention time of the unnecessary component is T, t <T, the target component flows out after time t after the start of inflow of the target component and the unnecessary component, and unnecessary after time T. Ingredients escape. Therefore, only the target component flows out of the column from time t to time T, and only the target component can be separated.
[0014]
Using this fact, only the target component can be continuously separated using n columns from the first column 11 to the nth column 1n. That is, the sample gas is sequentially introduced into the n columns from the first column 11 to the nth column 1n by the inflow side selection means 2 with a time difference. Then, the outflow destination of the column is switched to the output flow path 6 by the outflow side selection means 3 in accordance with the time zone in which only the target component flows out from each column, and the separated output is continuously supplied to the measuring device 4.
[0015]
In this way, by sequentially selecting the columns into which the sample gas flows in with a predetermined time difference and switching the outflow output of each column to the output flow path 6 at an appropriate timing, only the target component is continuously extracted from the sample gas. It can be separated and supplied to the measuring device 4. The measuring device 4 can continuously measure only the target component, determine the mass, volume, etc., and further determine the target component ratio in the sample gas. The start of the inflow into each column by the inflow side selection means 2 and the switching of the outflow output from each column to the output flow path 6 by the outflow side selection means 3 are controlled by the control unit 5 at a predetermined timing. .
[0016]
Next, the target component separation operation will be described in detail with reference to FIG. Fig.2 (a) is a figure which shows the time change of the sample gas which flows in into the continuous gas analyzer of this invention. The sample gas is a gas in which a target component and an unnecessary component are mixed as shown in the figure, and only the target component is a measurement target. The n columns from the first column 11 to the n-th column 1n are assumed to have a retention time of the target component t and a retention time T of the unnecessary component. At this time, t <T, and the target component flows out from each column earlier than the unnecessary component.
[0017]
FIG. 2B is a diagram showing temporal changes in the sample gas flowing out from the first column 11. Assuming that the sample gas starts to flow into the first column 11 at time 0, the target component starts to flow out of the first column 11 at time t and the unnecessary component starts at time T, as shown in FIG. The outflow starts from the first column 11. Therefore, only the target component is separated and flows out of the first column 11 from time t to time T.
[0018]
FIG. 2C is a diagram showing a temporal change in the sample gas flowing out from the second column 12. The sample gas starts to flow into the second column 12 from time (Tt). At this time, the inflow of the sample gas is also continued in the first column 11. As shown in FIG. 2C, only the target component is separated and flows out from the second column 12 from time T to time (2T-t). Therefore, if the effluent output from the first column 11 is switched to the effluent output from the second column 12 at time T and output to the output flow path 6, only the target component is measured from time t to time (2T-t). The device 4 can be supplied.
[0019]
Note that the flow of the sample gas into the first column 11 may be stopped at an appropriate time after the time T when the outflow output is switched to the second column 12. After stopping the flow of the sample gas, the first column 11 is cleaned by flowing a cleaning purge gas instead of the sample gas.
[0020]
In the same manner, the start of the flow of the sample gas into each column and the switching of the outflow output are performed. FIG. 2D is a diagram showing temporal changes in the sample gas flowing out from the third column (not shown). The sample gas starts to flow into the third column from time (2T-2t). The switching of the outflow output from the second column 12 to the third column is performed at time (2T-t). Further, the switching of the outflow output from the third column to the fourth column is performed at time (3T-2t).
[0021]
The inflow of the sample gas to the i-th i-th column from the top is started at time (i−1) · (T−t). Further, the switching of the outflow output from the (i−1) -th column to the i-th column is performed at time {(i−1) · (T−t) + t}. The switching of the outflow output from the i-th column to the (i + 1) -th column is performed at time {i · (T−t) + t}. The inflow of the sample gas to the i-th column may be stopped at an appropriate time after the time when the outflow output is switched to the (i + 1) -th column. After the flow of the sample gas is stopped, the purging gas for cleaning is flowed instead of the sample gas to clean the i-th column.
[0022]
FIG. 2 (e) is a diagram showing temporal changes in the sample gas supplied to the measuring device 4. As described above, the start of inflow of the sample gas into each column is sequentially performed at different times, and the sample gas outflow output is switched at the above-described time, so that as shown in FIG. The gas of only the target component separated in this way can be supplied to the measuring device 4. The measuring device 4 can continuously measure only the target component, determine the mass, volume, etc., and further determine the target component ratio in the sample gas.
[0023]
In the above description, in order to simplify the explanation of the principle of the present invention, the start of inflow of the sample gas into each column and the switching of the outflow output are performed at time intervals (Tt). Actually, it is preferable to set the switching time interval to be shorter than the difference between the holding time T of the unnecessary component and the holding time t of the target component. That is, it is preferable that the overlap time is d and the switching time interval is (Ttd). The overlap time d is a time for overlapping and flowing out the target component having the same concentration (the target component flowing in at the same time) from two adjacent columns.
[0024]
In this way, the outflow of the target component from each adjacent column overlaps with the overlap time d in terms of timing. That is, the time interval for switching the start of inflow to each column is shortened by the time width d (Ttd), and the timing for switching the outflow output from each column is switched around the center time of the overlap time d. It is desirable to make it.
[0025]
When the start of the flow of the sample gas into the i-th column is performed at time (i-1) · (Ttd), the time when the target component starts to flow out from the i-th column is {(i-1) · (T −t−d) + t}, and the time when the unnecessary component starts to flow is {(i−1) · (T−t−d) + T} = {i · (T−t−d) + t + d}. That is, only the target component flows out from the i-th column from the time {(i−1) · (T−t−d) + t} to the time {i · (T−t−d) + t + d}. . Similarly, only the target component flows out from the (i + 1) -th column between time {i · (T−t−d) + t} and time {(i + 1) · (T−t−d) + t + d}. Become.
[0026]
That is, in the time width d from the time {i · (T−t−d) + t} to the time {i · (T−t−d) + t + d}, the target component is over in the i-th column and the (i + 1) -th column. Wrap and spill. Similarly, in the time width d from time {(i−1) · (T−t−d) + t} to time {(i−1) · (T−t−d) + t + d}, (i−1) -th The target components overlap and flow out in the column and the i-th column.
[0027]
The output can be switched at any time within the range of the overlap time width d. It is desirable to switch the actual outflow output around the center time of the time width d. Accordingly, the switching of the outflow output from the (i−1) -th column to the i-th column is performed in the vicinity of time {(i−1) · (T−t−d) + t + d / 2}. Then, the switching of the outflow output from the i-th column to the (i + 1) -th column is performed in the vicinity of time {i · (T−t−d) + t + d / 2}. The inflow of the sample gas to the i-th column may be stopped at an appropriate time after the time when the outflow output is switched to the (i + 1) -th column. After the flow of the sample gas is stopped, the purging gas for cleaning is flowed instead of the sample gas to clean the i-th column.
[0028]
This overlap time d is a margin time for switching control. That is, as long as the output switching timing is within the range of the time width d, the output to the measuring device 4 is the same at any time. Therefore, there is a margin in the output switching timing. In addition, there is a margin in the inflow switching timing. Therefore, strict timing control is not required for switching control, and switching control can be easily performed. Further, it is possible to absorb the variation of the retention time T of the unnecessary component and the retention time t of the target component for each column to some extent. Note that, as the overlap time d is increased, there is a margin in the switching timing, but the time during which the target component can be separated by one column is shortened accordingly.
[0029]
Further, due to the volume in the inflow side selection means 2 and the volume in the flow passage, the inflow amount and the inflow concentration of the sample gas may become unstable in a short time zone immediately after the inflow switching. By providing the overlap time d, output switching can be performed while avoiding such an unstable time zone. Thereby, only the target component can be continuously separated without being affected by the volume in the valve in the inflow side selection means 2 or the volume in the circulation passage.
[0030]
Thus, according to the present invention, for example, continuous measurement such as continuously measuring changes in the amount of methane in the exhaust gas can be performed with almost no time delay. In this case, since the exhaust gas is not diluted with air and unnecessary components are not selectively burned, highly accurate measurement with a small measurement error is possible. In addition, the target component to be measured can be changed simply by changing the specifications and operating conditions such as the type of column packing, temperature, and flow rate. Furthermore, since the configuration of each part for separating the target component is simple, the cost of the continuous gas analysis method and apparatus can be reduced, and the occurrence of failure and the like is reduced.
[0031]
Here, it is assumed that the retention time of the unnecessary component that is not the measurement target is longer than the retention time of the target component. However, even if it is an unnecessary component that is not a measurement target, a component whose measurement result can be separated by the measuring device 4 does not necessarily have to be longer than the retention time of the target component. This is because such unnecessary components can be separated on the measuring device side.
[0032]
FIG. 3 is a diagram showing another form of the inflow side selection means 2. In this embodiment, three columns from the first column 11 to the third column 13 are used as the columns. The inflow side selection means 2 is composed of rotary valves 21-23. Depending on the state of the rotary valve, the sample gas can flow forward into each column. Further, when the flow of the sample gas to each column is stopped, the purge gas is flowed in the opposite direction to the sample gas to clean each column.
[0033]
The outflow side selection means 3, the output flow path 6 and the measuring device 4 are the same as those shown in FIG. The inflow start timing for each column and the outflow output switching timing for each column are the same as described in FIG. However, the inflow stoppage to each column is performed in a relatively short time after switching the outflow output to the next column. Further, after the third column 13, the first column 11 is selected, and each column is used repeatedly. The control unit 5 determines whether the inflow side selection means 2 (rotary valves 21 to 23) starts the inflow to each column and the outflow side selection means 3 switches the outflow output from each column to the output flow path 6. Execution control is performed at the timing.
[0034]
In this embodiment, the purge gas is allowed to flow in the direction opposite to the sample gas to clean each column, so that each column can be cleaned in a short time. Therefore, the number of columns is as small as three. Moreover, each column can be used repeatedly, and continuous measurement over a long time is possible.
[0035]
FIG. 4 is a diagram showing the state of the rotary valve 21 when the sample gas is allowed to flow into the first column 11 in the forward direction in the embodiment of FIG. When the rotary valve 21 is at this rotation angle, the sample gas flows in the forward direction (arrow direction) with respect to the first column 11 as shown in the figure. The sample gas flowing out from the first column 11 is sent to the outflow side selection means 3 (see FIG. 3) via the rotary valve 21 and the valve V1. At this time, the purge gas is discharged to the outside through the rotary valve 21 and the valves V2 and V3, and does not flow into the first column 11.
[0036]
FIG. 5 is a view showing a state of the rotary valve 21 when the purge gas flows into the first column 11 in the reverse direction. The rotary valve 21 is rotated 45 degrees from the state shown in FIG. When the rotary valve 21 is at this rotational angle, the purge gas flows into the first column 11 in the direction opposite to that shown in FIG. The purge gas flowing out in the reverse direction from the first column 11 is discharged to the outside through the rotary valve 21 and the valve V3.
[0037]
The purge gas branched from the middle is sent to the outflow side selection means 3 via the rotary valve 21 and the valve V1. At this time, the outflow side selecting means 3 is switched to send the outflow output of the other column to the measuring device 4. The sample gas is discharged to the outside through the rotary valve 21 and the valve V2, and does not flow into the first column 11. 4 and 5, the operation has been described by taking the first column 11 as an example, but the same applies to the other second column 12 and third column 13.
[0038]
As described above, when the flow of the sample gas into each column is stopped, the purge gas is allowed to flow in the direction opposite to the sample gas to clean each column, so that each column can be cleaned in a short time. Therefore, the number of columns can be reduced to a necessary minimum number, and the cost of the continuous gas analyzer can be reduced. Moreover, each column can be used repeatedly, and continuous measurement over a long time is possible.
[0039]
In addition, as the control part 5 which controls the inflow side selection means 2 and the outflow side selection means 3 in FIG. 1 and FIG. 3, the sequence controller etc. which perform these control according to time can be used. Alternatively, the control unit 5 can be realized by a computer or the like in common with the control unit of the measuring device 4. Moreover, as the measuring device 4, a mass spectrometer such as a single-convergent magnetic field mass spectrometer, or any other analyzer or analyzer capable of continuous measurement can be used.
[0040]
Further, it is desirable that the plurality of columns have the same retention time for the target component and the same retention time for the unnecessary component in each column. However, even if the holding times under the same conditions are different, the conditions of each column such as the flow rate and the temperature may be adjusted so that the holding time does not differ between the columns. Furthermore, even if there is a difference in holding time in each column, only the target component may be separated continuously by adjusting the inflow start time and the outflow output switching time by the control unit 5.
[0041]
In the above embodiment, the mixed gas is described as an example of the sample fluid. However, the present invention can be applied to other sample fluids such as a liquid. In addition, the example in which the separation output of the sample fluid is continuously analyzed and measured by the measuring device is described, but the separation output of the sample fluid may be processed by another processing device, or the sample fluid may be processed from the sample fluid. Only the target component may be separated.
[0042]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0043]
The flow of sample fluid into multiple columns is started at different times, and the sample fluid outflow output is switched to output to the output channel, so that only the target component can be separated continuously. it can. The separated output can be continuously processed by a measuring device or other processing device.
[0044]
Since the sample fluid starts to flow into multiple columns at different times, and the sample fluid outflow output is switched and supplied to the detection means, only the target component that has been continuously separated is used as the detection means. Can be supplied. The detection means can perform continuous measurement of only the target component with almost no time delay. In the measurement of exhaust gas, since the exhaust gas is not diluted with air and unnecessary components are not selectively burned, high-precision measurement with a small measurement error is possible. In addition, the target component to be measured can be changed simply by changing the specifications and operating conditions such as the type of column packing, temperature, and flow rate. Furthermore, since the configuration of each part for separating the target component is simple, the cost of the continuous fluid analysis method and apparatus can be reduced, and the occurrence of failure and the like is reduced.
[0045]
Since the cleaning fluid such as purge gas is allowed to flow in the opposite direction to the sample fluid when the flow of the sample fluid into each column is stopped, each column can be cleaned in a short time. Therefore, the number of columns can be reduced to a necessary minimum number, and the cost of the continuous fluid analyzer can be reduced. Moreover, each column can be used repeatedly, and continuous measurement over a long time is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a continuous gas analyzer of the present invention.
FIG. 2 is a diagram showing a separation operation of a target component in the present invention.
FIG. 3 is a diagram showing another form of the inflow side selection means.
FIG. 4 is a view showing a state of a rotary valve when a sample gas is allowed to flow in a column in a forward direction.
FIG. 5 is a view showing a state of a rotary valve when purge gas is allowed to flow in the column in the reverse direction.
[Explanation of symbols]
2 ... Inflow side selection means 3 ... Outflow side selection means 4 ... Measuring device 5 ... Control part 6 ... Output flow path 11 ... 1st column 12 ... 2nd column 13 ... 3rd column 1n ... n-th columns 21-23 ... Rotary Valve V1, V2, V3 ... Valve

Claims (5)

A plurality of columns (11-13, 1n) in which the retention time of the target component fluid is substantially the same and the retention time of the unnecessary component fluid is longer than the retention time of the target component fluid, and an output flow path for outputting the target component fluid ( 6) a continuous fluid separation method according to
A procedure for starting the flow of the sample fluid at a predetermined timing for each of the columns (11 to 13, 1n);
A continuous fluid having a procedure of switching only the fluid flowing out from the column to output from the output flow path (6) in a time zone when only the target component fluid flows out from each of the columns (11 to 13, 1n). Separation method. A plurality of columns (11-13, 1n) in which the retention time of the target component fluid is substantially the same and the retention time of the unnecessary component fluid is longer than the retention time of the target component fluid, and detection means (4) for detecting the target component fluid ) And a continuous fluid analysis method,
A procedure for starting the flow of the sample fluid at a predetermined timing for each of the columns (11 to 13, 1n);
A procedure for switching to supply only the fluid flowing out from the column to the detection means (4) in a time zone when only the target component fluid flows out from each of the columns (11 to 13, 1n);
A continuous fluid analysis method comprising a step of continuously measuring a target component fluid by the detection means (4). A plurality of columns (11-13, 1n) having the same retention time of the target component fluid and a retention time of the unnecessary component fluid being larger than the retention time of the target component fluid;
An output channel (6) for outputting a target component fluid;
Inflow side selection means (2, provided on the inflow side of the plurality of columns (11-13, 1n) for selectively flowing the sample fluid into at least one of the plurality of columns (11-13, 1n) 21-23),
Outflow that is provided on the outflow side of the plurality of columns (11-13, 1n), and that selects the sample fluid flowing out from the plurality of columns (11-13, 1n) and outputs the selected sample fluid to the output flow path (6). Side selection means (3);
By controlling the inflow side selection means (2, 21 to 23) and the outflow side selection means (3), only the target component fluid in the sample fluid is continuously output from the output flow path (6). A continuous fluid separator having a control means (5). A plurality of columns (11-13, 1n) having the same retention time of the target component fluid and a retention time of the unnecessary component fluid being larger than the retention time of the target component fluid;
Detection means (4) for detecting a target component fluid;
Inflow side selection means (2, provided on the inflow side of the plurality of columns (11-13, 1n) for selectively flowing the sample fluid into at least one of the plurality of columns (11-13, 1n) 21-23),
Outflow side provided on the outflow side of the plurality of columns (11-13, 1n) and selecting the sample fluid flowing out from the plurality of columns (11-13, 1n) and supplying it to the detection means (4) Selection means (3);
Control for controlling only the inflow side selection means (2, 21 to 23) and the outflow side selection means (3) to continuously supply only the target component fluid in the sample fluid to the detection means (4). A continuous fluid analyzer comprising means (5). The continuous fluid analyzer according to claim 4, wherein
The inflow side selection means (21 to 23) allows the sample fluid to flow into the columns (11 to 13) in the forward direction and the cleaning fluid to flow into the columns (11 to 13) in the reverse direction. A continuous fluid analyzer that switches between states.

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