JPH04270946A - Method for analyzing exhaust gas of diesel engine - Google Patents

Abstract

PURPOSE:To simply analyze the exhaust gas of a diesel engine within a short time with high accuracy even by an unskilled person. CONSTITUTION:A constant volume of the exhaust gas from a diesel engine is allowed to flow to a flow passage having a filter 2 arranged thereon and the particulate in the exhaust gas is collected by the filter 2. The filter 2 is heated in a heating oven 1 to burn HC, C and S in the particulate and the formed combustion gas is brought into contact with an oxidizing catalyst 18 and guided to an analyzer 7 to be analyzed.

Description

[Detailed description of the invention]

0001

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

0002

[Prior Art] As a method for measuring particulates in diesel engine exhaust gas, a fixed volume of high-temperature exhaust gas discharged from a diesel engine is introduced into a gas flow path, and a collection filter is installed in the gas flow path. By,
A filter collection method is generally known in which particulates are collected, the filter is weighed using a precision balance, and quantitative analysis is performed based on the weight difference between the filter and the filter before particulate collection.

0003

However, in the above-mentioned filter collection method, the water adsorbed on the filter has a large effect on the measurement error, so heat treatment at a temperature that only removes the water in the filter is required.

[0004] Also, particulates usually contain sof (soluble organ), which is dissolved in organic solvents.
a volatile HC component called ic fraction),
It contains a C component called soot, sulfate, etc. (a) sof is organic solvent extraction, and (b) su
lfate must be extracted and measured using distilled water or an eluent for ion chromatography. Therefore, it takes several hours to complete all measurements, and the work itself requires great skill, which has the disadvantage that analysis results vary from person to person.

The present invention has been made with the above-mentioned considerations in mind, and its purpose is to provide a diesel engine exhaust gas analysis method that allows even non-experts to easily perform high-precision measurements in a short period of time. The purpose is to provide a method.

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the diesel engine exhaust gas analysis method according to the present invention includes a first aspect of the present invention, in which a fixed volume of exhaust gas from a diesel engine is passed through a flow path in which a filter is installed. The particulates in the exhaust gas were collected by the filter, the filter was heated in a heating furnace to burn HC, C, and S in the particulates, and the combustion gas was brought into contact with an oxidation catalyst. Afterwards, it is guided to an analyzer for analysis.

Further, in the second invention, a fixed volume of exhaust gas from a diesel engine is caused to flow through a flow path in which a filter is installed, particulates in the exhaust gas are collected by the filter, and this filter is equipped with an oxidation catalyst. The particulates are heated in a heating furnace to combust the HC, C, and S in the particulates, and the combustion gas is led to an analyzer for analysis.

[0008]

[Operation] According to the above characteristic structure, a filter that has collected particulates in a fixed volume of diesel engine exhaust gas is heated in a heating furnace to remove H in the particulates.
Since C, C, and S are combusted and the combustion gas generated at that time is guided to an analyzer for analysis, heat treatment to remove moisture in the filter (however, heat treatment may not be necessary depending on the content to be evaluated) is required. Quantitative analysis can be performed in a very short time without the need for pre-treatment such as solvent extraction, and since there is no need to use a precision balance or organic solvent, there are no individual differences in analysis results. Even non-experts can perform highly accurate measurements.

[0009] Furthermore, even if the temperature inside the heating furnace is low and incomplete combustion occurs, the oxidation catalyst reliably oxidizes, thereby improving measurement accuracy. Furthermore, since the temperature inside the furnace can be set low, stable combustion is possible without deflagration, and the heating furnace length (soaking length) can be shortened, making the furnace structure smaller and lighter. can.

Furthermore, according to the second invention, since the oxidation catalyst is placed in the heating furnace, the entire apparatus can be further downsized.

[0011]

[Example] Hereinafter, embodiments of the present invention will be explained based on the drawings. Fig. 1 shows a first embodiment of the diesel engine exhaust gas analysis method according to the present invention. First, a constant volume of high-temperature exhaust gas from a diesel engine is caused to flow through a flow path (not shown) in which this filter 2 is installed, and particulates in the exhaust gas are collected by the filter 2. Then, this filter 2 is installed in a heating combustion furnace 1 consisting of, for example, an electric resistance furnace. The heating combustion furnace 1 is configured to be supplied with O2 via a protective filter 3, a solenoid valve 4, a pressure regulator 5, and a needle valve 6.

Reference numeral 18 denotes an oxidation catalyst installed immediately after the heating combustion furnace 1, and is made of, for example, a quartz tube filled with an oxidation catalyst made of an alumina carrier coated with platinum, and the inside of the oxidation catalyst is kept at about 600 to 800°C. It's heated. 7 is, for example, a non-dispersive infrared gas analyzer (hereinafter referred to as NDIR) for detecting the combustion gas that has passed through the oxidation catalyst 18; H2O, CO2, SO2
It is constructed by optically arranging H2O detectors, CO2 detectors, and SO2 detectors (not shown) in series or parallel to each other for simultaneously detecting a plurality of gases such as gases.

Reference numeral 11 denotes a purge bypass channel equipped with a needle valve 12 and a solenoid valve 13. 14 is NDIR7
15 is a linearizer for correcting the curvature of the output signal; 16 is a preamplifier for amplifying the output signal from NDIR7;
, S, 17 is an HC,
This is a display for displaying each weight of C and S.

[0014] Then, the solenoid valves 4 and 8 are opened and the solenoid valve 13 is closed to introduce O2 into the heating combustion furnace 1, and at the same time, the inside of the heating combustion furnace 1 is heated to about 600 to 800°C, and an oxygen air flow is generated. Inside, HC, C, and S in the particulates collected by the filter 2 are combusted. As a result, many of HC, C, and S are oxidized to H2O, CO2
, SO2, and the remaining components that were not completely oxidized are also completely oxidized in the oxidation catalyst 18, and these combustion gases are introduced into the NDIR 7.

[0015] The above H2O, CO2, SO2 are ND
H2 O detector, CO2 detector installed in IR7,
It is detected by an SO2 detector (not shown) and output as a signal corresponding to each gas concentration (volume%). This output signal is amplified and linearized by a preamplifier 14 and a linearizer 15, and then arithmetic circuit 1
6, the weight is converted into HC, C, and S (mg) and displayed on the display 17.

[0016] That is, the gases whose respective concentrations of H2 O, CO2, and SO2 are C1, C2, and C3 have a flow rate L(
H2 O, CO2, S when flowing at l/min)
The total amount of each gas in O2 is X1 (H2 O) = L/60
×∫C1 dt (l)X2(CO2) =L/6
0×∫C2 dt(l)X3(SO2) =L/60
×∫C3 dt(l), and the weights of C, H, and S components contained in each gas are calculated by the following formula.

[0017]

[Math 1]

[0018]

[Math 2]

[0019]

[Math 3]

[0020] Also, a constant volume of exhaust gas is allowed to flow through the filter 2.
By inputting the amount of gas required to collect particulates into the calculation circuit 16, the following equation can be obtained.

[0021]

[Equation 4] It is also possible to display it in units of (mg/m3). In addition, when purging is performed after the measurement is completed, the solenoid valves 4 and 13 are opened, the solenoid valve 8 is closed, and the O2
Just install it and purge.

From the above results, the amounts of sof, soot, and sulfate in diesel engine exhaust gas are respectively

[0023]

[Math 5]

[0024]

[Math 6] It can be found as

[0025] Also, here sof and soot
H (mg) in H2 SO4 (sulfate)
2 is also added up and measured higher by that amount, so if H2, which is assumed by the amount of S, is subtracted, the measurement can be made more accurately.

FIG. 2 shows the relationship between the amount of generated particles and the engine load, with the vertical axis representing the property ratio of particulate matter and the horizontal axis representing the engine load ratio. In the same figure, the solid line indicates Dry so
ot, the dashed line shows sof, and the dashed line shows changes in sulfate ions. FIG. 3 shows the amount of particulates, which is the sum of each component shown in FIG. 2, where the vertical axis represents the concentration ratio of particulates, and the horizontal axis represents the engine load factor.

From this, if evaluation is to be performed under conditions of low sof and high engine load, it is sufficient to analyze only the C and S components without analyzing the H component.

FIG. 4 shows a second embodiment of the present invention, which is the same as the first embodiment except that the oxidation catalyst 18 is placed in the heating combustion furnace 1. And Figure 5 shows this second
CO2 against combustion temperature in heating combustion furnace 1 according to example
2 is a diagram showing changes in the amount of CO gas generated, and as is clear from this diagram, according to this example, the temperature is relatively low (6
CO2 is generated stably from around 00°C.
On the contrary, the generation of CO has not been observed over the entire temperature range. Furthermore, when an oxidation catalyst is not used, the amount of CO2 generated increases as the combustion temperature increases, but CO is also constantly generated. Therefore, by using an oxidation catalyst, it is possible to This made it possible to oxidize and perform extremely accurate measurements.

In this example, a non-dispersive infrared gas analyzer (NDIR) is used as the analyzer, but the analyzer is not limited to this. For example, a thermal conductivity analyzer (TCD) or the like may be used. It's okay.

[0030]

[Effects of the Invention] As explained above, according to the present invention,
A filter that has collected particulates in a fixed volume of diesel engine exhaust gas is heated in a heating furnace to combust HC, C, and S in the particulates, and the combustion gas generated at that time is led to an analyzer and analyzed. As a result, quantitative analysis can be performed in a very short time without the need for pretreatment such as heat treatment or solvent extraction to remove water in the filter, and it also allows for the use of precision balances and organic solvents. Since there is no need to do this, there are no individual differences in analysis results, and even non-experts can perform highly accurate measurements.

Furthermore, even if the temperature inside the heating furnace is low and incomplete combustion occurs, the oxidation catalyst ensures oxidation, which improves measurement accuracy. Furthermore, since the temperature inside the furnace can be set low, stable combustion is possible without deflagration, and the heating furnace length (soaking length) can be shortened, making the furnace structure smaller and lighter. can.

Furthermore, according to the second invention, since the oxidation catalyst is placed in the heating furnace, the entire apparatus can be further downsized.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a diesel engine exhaust gas analyzer.

FIG. 2 is a diagram showing the relationship between the amount of generated particles of each component and the engine load.

FIG. 3 is a diagram showing the relationship between the amount of particulates generated and the engine load.

FIG. 4 is an overall configuration diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the amount of gas generated and the combustion temperature.

[Explanation of symbols]

1... Heating (combustion) furnace, 2... Filter, 7... Analyzer, 18
...oxidation catalyst.

Claims (2)

[Claims] 1. A fixed volume of exhaust gas from a diesel engine is flowed through a flow path in which a filter is installed, particulates in the exhaust gas are collected by the filter, and the filter is heated in a heating furnace to remove the particulates. A method for analyzing exhaust gas from a diesel engine, characterized in that HC, C, and S in a curate are combusted, the combustion gas is brought into contact with an oxidation catalyst, and then guided to an analyzer for analysis. [Claim 2] A fixed volume of exhaust gas from a diesel engine is caused to flow through a flow path in which a filter is installed, particulates in the exhaust gas are collected by the filter, and the filter is placed in a heating furnace in which an oxidation catalyst is mounted. A method for analyzing exhaust gas from a diesel engine, characterized in that the HC, C, and S in the particulates are combusted by heating, and the combustion gas is introduced into an analyzer for analysis.