JPH04331352A - Particulate analysis device - Google Patents

Abstract

PURPOSE:To enable a particulate analysis of a diesel engine exhaust gas to be performed automatically and continuously. CONSTITUTION:A taper-shaped filter 1 is passed continuously at a fixed speed in the order of a sample channel 5 which supplies a fixed flow of exhaust gas from a diesel engine and a heating combustion furnace 12 for combusting a particulate which is adhered to the filter 1 under O2 atmosphere. A combustion gas which is obtained by the heating combustion furnace 12 is analyzed continuously by an analysis meter 18 along with it. The sample channel 5 is constituted by setting an upstream side of a ductwork for sucking a fixed flow of air by a pump 8 to be a Venturi pipe 6 and then connecting a sample introduction pipe 7 which introduces one portion of exhaust gas from a diesel engine 4 to a throat portion 6a of the Venturi pipe 6 for supplying a fixed flow of exhaust gas.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particulate analyzer for quantitatively analyzing particulate matter (fine particulate matter such as soot) in diesel engine exhaust gas.

0002

[Prior Art] As shown in Fig. 3, a method for measuring particulates in diesel engine exhaust gas is as follows.
High-temperature exhaust gas discharged from the diesel engine 25 is supplied in a fixed amount into a gas flow path such as a dilution tunnel 26, and the exhaust gas is led out at a constant flow rate from the downstream part of the dilution tunnel 26 via a branch pipe 27. The contained particulates are collected by a collection filter 29 interposed in the branch pipe 27, and the filter 29 is weighed using a precision balance or the like to remove the particulates from the filter 2 before collecting the particulates.
A filter collection method is generally known in which quantitative analysis is performed based on the weight difference with 9.

[0003] Furthermore, the dilution tunnel 26
is a tunnel for diluting and cooling the exhaust gas introduced from the upstream part with normal temperature air introduced from the outside via the air filter 24. On the downstream side of this dilution tunnel 26, there is a CVS (Constant Vol.
ume Sampler) device 28 is connected.

In the case of this filter collection method, the filter 2
Since the moisture adsorbed in the filter 29 has a large effect on measurement errors, heat treatment at a temperature that removes only the moisture in the filter 29 is required. In addition, particulates usually contain sof (soluble organ), which is dissolved in organic solvents.
Volatile HC component called n-ic fraction), C (soot) called ds (dry soot)
Contains ingredients such as sulfate,
Sof must be measured by organic solvent extraction, and sulfide salts must be extracted and measured using distilled water or an eluent for ion chromatography. Therefore, in the above method, it takes several hours to complete all measurements, and the work itself requires a high level of skill, resulting in individual differences in analysis results.

Therefore, as an alternative method, as shown in FIG. 4, a filter 29 installed in a flow path through which exhaust gas from a diesel engine is supplied in a fixed amount to collect particulates in the exhaust gas is heated. HC and C in the particulates are heated stepwise in a furnace 30.
, S is combusted, the combustion gas is brought into contact with an oxidation catalyst 31, and then introduced into an analyzer 32 for analysis. In FIG. 4, a combustion gas detection signal detected by an analyzer 32 is amplified by a preamplifier 33 and inputted to an arithmetic unit 34, and based on the input signal, H
The weights of C, C, and S are calculated by the calculating section 34. In the case of this method, since the processing after filter installation can be automated, the time required for measurement can be shortened, and individual differences in analysis results can be eliminated to some extent.

[0006]

[Problems to be Solved by the Invention] However, even in the case of the above method, the filter 29 after collecting particulates is
The work of taking it out from the exhaust gas flow path and installing it in the heating furnace 30 needs to be done manually. Therefore, there is a very high possibility that impurities other than particulates will adhere to the filter 29 during the process, and there is a problem in that these impurities will cause errors in the analysis results.

[0007] Furthermore, since the filter must be installed at each measurement point, there is also the problem that continuous measurement of exhaust gas emitted from a diesel engine is not possible. Furthermore, since this method also involves manual work, there remains the problem that individual differences in analysis results cannot be avoided.

In view of the above-mentioned conventional drawbacks, the present invention aims to provide a particulate analyzer that can perform automatic and continuous measurement without intervening error factors such as individual differences and impurities.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a venturi pipe for introducing air into the upstream part, and a part of the exhaust gas from the diesel engine is delivered to the throat part of the venturi pipe. A sample flow path is connected to the sample introduction tube that introduces the sample, and the exhaust gas diluted with air is sucked in by a pump and supplied at a constant flow rate. A tape-shaped filter that collects particulates in the exhaust gas and a tape-shaped filter that has crossed the sample flow path are heated while being passed through the tape-shaped filter continuously at the same speed as the feeding speed to collect the collected particles. It is characterized by being equipped with a heating combustion furnace that burns the HC, C, and S in the curate, and an analyzer that analyzes the combustion gas produced by this heating combustion furnace.

0010

[Operation] According to the above configuration, quantitative analysis of particulates can be continuously performed by moving the tape filter at a constant speed from the sample channel, which is the exhaust gas supply section, to the heating combustion furnace. , it can save labor such as manual installation of filters. As air is introduced from the venturi tube into the sample flow path, a portion of the diesel engine exhaust gas is introduced from the sample introduction tube connected to the throat of the venturi tube, creating a flow path with less unevenness. A part of the exhaust gas can be supplied at a constant flow rate through the flow path, and part of the particulates can be prevented from being captured in the middle of the flow path.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a schematic diagram schematically showing the configuration of a particulate analyzer according to the present invention. In the figure, a tape-shaped filter 1 is used to collect particulates in exhaust gas discharged from a diesel engine 4, and is made of, for example, quartz fiber, and is filtered at a constant speed from a loader-side roll 2 that has been wound in advance. It is fed out and wound onto the unloader side roll 3.

In the middle of the moving path of the tape-shaped filter 1, a sample flow path 5 that supplies a fixed amount of part of the exhaust gas discharged from the diesel engine 4 to the tape-shaped filter 1 intersects with the tape-shaped filter 1. It is arranged so that

The upstream side of the sample flow path 5 consists of a venturi tube 6, one end of which is open to the outside air via an air filter (not shown), etc., and the throat portion 6a of the venturi tube 6 is connected to the exhaust gas from the diesel engine 4. A sample introduction tube 7 is connected to introduce a part of the gas. Note that these members are desirably made of a metal material, such as stainless steel, that does not carry static electricity.

In addition, a suction pump 8 is provided downstream of the intersection of the sample channel 5 with the tape-shaped filter 1, and a suction pump 8 is provided to collect air taken in from the Venturi tube 6 and exhaust gas introduced from the sample introduction tube 7. A mixture of gas and a portion of purge air, which will be described later, is sucked and exhausted by the suction pump 8 .

Furthermore, between the intersection of the sample channel 5 with the tape-shaped filter 1 and the Venturi tube 6, the exhaust gas introduced from the sample introduction tube 7 is diluted with air taken in from the Venturi tube 6. A dilution tunnel 9 for cooling is provided.

At the intersection of the sample flow path 5 with the tape-shaped filter 1, the sample flow path 5 is divided so that the tape-shaped filter 1 can be moved across the sample flow path 5.

The divided portion of the sample flow path 5 is surrounded by a sealing chamber 10 to prevent exhaust gas from leaking out of the flow path from this divided portion. This empty chamber 10 includes an inlet 10a and an outlet 10a through which the tape-shaped filter 1 passes.
0b, and an air introduction port 10c for introducing purge air that serves as an air curtain to prevent leakage of exhaust gas. In addition, the creepage distance of the air curtain seal should be as long as possible, and the gap that allows the tape-shaped filter 1 to pass should be made as narrow as possible (approximately 1.1 to 1.5 times the thickness of the tape-shaped filter 1). This is desirable.

The supply flow rate Qp1 of the purge air introduced from the air inlet port 10c of the sealing chamber 10 is such that the pressure of the purge air in the sealing chamber 5 reaches the sample flow path 5.
in order to exceed the pressure of the gas in the sample flow path 5.
is determined so that no gas leaks into the empty space 10.

Furthermore, the exhaust flow rate Qb by the suction pump 8 on the downstream side of the sample channel 5 is determined to be constant. That is, from the diesel engine to the sample flow path 5
When the constant flow rate of the diluted exhaust gas supplied to is Qs, the exhaust flow rate Qb by the suction pump 8 is Qb = Q
s + ΔQp1. However, ΔQp1 represents the flow rate (constant) of the purge air flowing into the sample flow path 5.

A purge section 11 is disposed in the middle of the moving path of the tape-shaped filter 1 on the downstream side of the intersection of the sample flow paths 5. The purge section 11 blows a gas containing few impurities such as CO, CO2, and HC such as N2 or cylinder air onto the tape-shaped filter 1.
This is to remove gaseous components other than particulates such as CO, CO2, and HC from the collected substances, as well as moisture adsorbed on the filter 1.

Furthermore, a heating combustion furnace 12 is disposed in the movement path of the tape-shaped filter 1 on the downstream side of the purge section 11 to allow the tape-shaped filter 1 to pass therethrough and heat the filter 1. . This heating combustion furnace 12 includes a window 12a that transmits radiant heat from a heating source 13 such as an infrared reverberating furnace or a CO2 laser, and an O2 inside the heating combustion furnace 12.
2 or air supply ports 12b and 12c for supplying air as carrier gas or purge gas are provided. The carrier gas is a gas that creates an O2 atmosphere inside the heating combustion furnace 12, and the purge gas is a gas that seals the filter entrance and exit of the heating combustion furnace 12.

Further, on the side of the heating combustion furnace 12 facing the above-mentioned air supply ports 12b and 12c with the tape-shaped filter 1 passing portion in between, there is an air intake passage 14 for sucking the combustion gas generated in the heating combustion furnace 12. is connected. An oxidation catalyst section 15 is interposed in the middle of this intake passage 14. The oxidation catalyst section 15 is made of, for example, a quartz tube filled with an oxidation catalyst made of an alumina carrier coated with platinum, and the inside thereof is heated to about 600 to 800 degrees Celsius.

[0023] On the downstream side of the intake passage 14, there is a C for quantitative sampling.
A VS device 16 and a suction pump 17 are connected, whereby a constant flow rate Qm of combustion gas is sampled from the heating combustion furnace 12 through the intake passage 14. For example, a constant flow rate Qc of carrier gas is supplied from the air supply port 12b of the heating combustion furnace 12,
Further, assuming that a constant flow rate Qp2 of purge gas is supplied into the furnace from the air supply port 12c, the flow rate Qm of the combustion gas collected from the heating combustion furnace 8 is Qm = Qc + ΔQp2. However, ΔQp2 represents the flow rate (constant) of the purge gas supplied into the furnace flowing into the intake passage 10.

On the downstream side of the suction pump 17, for example, a non-dispersive infrared gas analyzer (hereinafter referred to as NDIR) 18 is provided for detecting the component concentration of the sampled combustion gas. This NDIR18 is, for example, H2O, CO2
, SO2 and the like are optically arranged in series or parallel to each other.

Preamplifiers 19, 20, and 21 are connected to the next stage of the NDIR 18 to amplify the detection signals from the respective detectors of the NDIR 18, and the amplified detection signals are input to the next stage, and these amplified detection signals are input. an arithmetic circuit 2 that performs calculations to convert the concentrations of combustion gases H2O, CO2, and SO2 into the weights of HC, C, and S based on the detection signals of the
2 are connected.

Next, the operation of quantitatively analyzing particulates by the above analyzer will be explained. The tape-shaped filter 1 unwound from the loader-side roll 2 is wound onto the unloader-side roll 3 at a constant speed. Thereby, the tape-shaped filter 1 passes through the sample channel 5, the purge section 11, and the heating combustion furnace 12 in the order in which they are arranged. When crossing the sample channel 5, a constant flow rate Qs of diluted exhaust gas supplied from the diesel engine 4 via the sample channel 5 passes through the tape filter 1. As a result, particulates in the exhaust gas are collected on the tape-shaped filter 1.

In the venturi tube 6 of the sample flow path 5, exhaust gas is introduced from the diesel engine 4 via the sample introduction tube 7 at a constant flow rate relative to the constant flow rate of air taken in from its open end. As a result, the sample channel 5 is supplied with exhaust gas diluted with air at a constant flow rate Qs. FIG. 2 is a graph showing a comparative relationship between the air flow rate taken in from the open end of the venturi tube 6 and the sample flow rate of exhaust gas introduced from the sample introduction tube 7, and the relationship curve is
and a sample introduction tube 7 connected to its throat portion 6a.
By changing the structure and dimensions of the curves, curves (A), (B), and (C) can be arbitrarily set.

[0028] When the exhaust gas discharged from the diesel engine 4 is directly sampled as in the embodiment, the ratio between the air flow rate and the exhaust gas sample flow rate is 1.
It is desirable that the ratio be about 0:1. Further, when sampling the entire amount of exhaust gas from the diesel engine 4 after diluting it in the dilution tunnel 26 as shown in FIG. .

The sample flow path 5 may be configured by connecting a suction pump, a constant pressure regulator, a capillary, etc., or may be provided with a needle valve and a flow rate detector in the flow path, and the sample flow path may be configured by connecting a suction pump, a constant pressure regulator, a capillary, etc. A common configuration is to supply a constant flow rate by controlling the rotation speed of the pump and the opening degree of the needle valve with a controller.

Incidentally, when such a general configuration is adopted as the sample flow path 5, since the flow path has many unevenness, some of the particulates in the exhaust gas are trapped in the unevenness. This causes a problem in that it is captured and becomes a factor in reducing measurement accuracy. On the other hand, in the configuration of the sample flow path 5 of the embodiment, since the unevenness of the flow path is reduced, trapping of particulates on the way can be sufficiently avoided.

Furthermore, in this embodiment, since the exhaust gas is diluted and cooled by the dilution tunnel 9 provided downstream of the venturi tube 6, the entire amount of exhaust gas from the diesel engine 25 shown in FIG. 3 is diluted and cooled. It is possible to obtain analysis results that are correlated with analysis data obtained when diluting and cooling in the solution tunnel 26.

Now, when the tape-shaped filter 1 that has collected particulates passes the intersection with the sample flow path 5 and approaches the purge section 11, a gas such as N2 is blown against the tape-shaped filter 1. As a result, gas components such as CO, CO2, and HC, which are substances other than particulates, and moisture adsorbed on the filter 1 are removed from the substances collected on the tape-shaped filter 1.

Next, when entering the heating combustion furnace 8, the tape-shaped filter 1 is heated in an O2 atmosphere. As a result, the particulates adhering to the tape-shaped filter 1 are combusted and changed into combustion gases such as CO2, H2O, and SO2. This combustion gas is sucked into the intake passage 14, and is supplied in a constant amount to the NDIR 18 via the oxidation catalyst section 15. Even if the combustion gas contains CO and HC that were incompletely combusted in the heating combustion furnace 12, these gases are completely combusted in the oxidation catalyst section 15 midway and become CO.
2, H2O.

[0034] CO2 and H are completely removed through the oxidation catalyst section 15.
Each combustion gas that has become 2 O, SO2 has an NDIR of 18
are detected by each detector. The detection signals are amplified by the corresponding preamplifiers 19, 20, and 21 and input to the arithmetic circuit 22, where they are converted into the weights (mg) of HC, C, and S.

By the way, if the time required for the tape-shaped filter 1 to cross the sample channel 5 until it passes through the heating and combustion furnace 12 is t, then the analysis result of the particulates obtained by the arithmetic circuit 22 is as follows. The data corresponds to the exhaust gas that was supplied to the sample flow path 5 at a time t before the current time. That is, in this case, the analysis result is delayed by the time t. Therefore, when analyzing the analysis results, it is only necessary to take this time delay into consideration and associate the analysis data with the exhaust gas.

In this embodiment, the case where a non-dispersive infrared gas analyzer (NDIR) 18 is used as the analyzer has been explained, but the present invention is not limited to this, and for example, a thermal conductivity analyzer (TCD) or the like can be used. May be used.

[0037]

Effects of the Invention The present invention has the above-mentioned configuration, and includes a sample flow path that supplies a constant flow of exhaust gas from a diesel engine to a tape-shaped filter, and heating for burning particulates attached to the filter in an O2 atmosphere. The combustion gas is passed through each combustion furnace in this order at a constant speed, and the combustion gas in the heating combustion furnace is analyzed by an analyzer, so there is no need for manual work such as installing filters, and the process is automatic and efficient. Continuous measurement becomes possible. In addition, the sample flow path is designed so that as a constant flow rate of air is sucked from the Venturi tube, a portion of the diesel engine exhaust gas is introduced at a constant flow rate from the sample introduction tube connected to the throat of the Venturi tube. Because of this, a part of the exhaust gas can be supplied at a constant flow rate through a flow path with few irregularities.
Particulates are not trapped in the middle of the flow path, allowing highly accurate measurement.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing the outline of a particulate analyzer according to an embodiment of the present invention.

FIG. 2 is a graph showing a comparative relationship between the air flow rate supplied to the sample flow path of the particulate analyzer of the example and the sample flow rate of exhaust gas.

FIG. 3 is a diagram schematically showing an outline of a conventional device for collecting particulates using a filter.

FIG. 4 is a diagram schematically showing an example of a measurement system that performs quantitative analysis of particulates based on particulates collected by a filter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Tape filter, 5...Sample channel, 6...Venturi tube, 6a...Throat part, 7...Sample introduction tube, 8...
Pump, 12... heating combustion furnace, 18... analyzer.

Claims (1)

[Claims] Claim 1: A venturi pipe for introducing air is provided at the upstream part, and a sample introduction pipe for introducing a part of the exhaust gas from the diesel engine is connected to the throat part of this venturi pipe, so that the exhaust gas diluted by the air is A sample flow path that is sucked by a pump and supplied with a constant flow rate; a tape-shaped filter that is fed out at a constant speed to continuously cross the sample flow path to collect particulates in the exhaust gas; a heating combustion furnace that burns HC, C, and S in the collected particulates by heating the tape-shaped filter that has crossed the sample flow path while continuously passing it at the same speed as the feeding speed; A particulate analyzer characterized by comprising an analyzer for analyzing combustion gas from a heating combustion furnace.