JP3035115B2 - Particulate continuous analysis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a particulate continuous analysis method capable of continuously and quantitatively analyzing particulates (particulate matter such as soot) contained in exhaust gas discharged from a diesel engine or the like.

[0002]

2. Description of the Related Art As a conventional method for measuring particulates contained in exhaust gas of a diesel engine, high-temperature exhaust gas discharged from a diesel engine is introduced into a constant flow sampling device, and a fixed amount of sample is sampled downstream of the constant flow sampling device. The gas is divided and the particulates are collected by a collection filter. There is a filter collection / balance weighing method in which the filter is weighed by a precision balance or the like, and the weight difference before and after collection is determined to perform quantitative analysis.

However, in the above-described filter collection and weighing method, since the moisture adsorbed on the filter has a large effect as a measurement error, the temperature in the filter before and after the collection is kept constant at a constant temperature and a constant humidity. Processing is required. In addition, this measurement method has a disadvantage that continuous measurement cannot be performed because the filter that collects particulates is removed from the gas flow path for operation.

[0004] In particulates, SOF (Soluble Organic Fraction) which is usually dissolved in an organic solvent is used.
Volatile hydrocarbons (HC) called dry soot (Dr
y soot; C) component called s)
It referred ulfate SO ₄ ^- are included such as, but, SO
Since F needs to be extracted with an organic solvent and sulfate needs to be extracted with distilled water or an eluent for ion chromatography, it takes a long time for the whole measurement. Furthermore, since the work itself requires skill, the analysis results vary from person to person.

[0005] In order to solve the drawbacks of the filter collecting and weighing method, there are known an instantaneous fine particle concentration meter that detects a change in weight when a particulate is collected by a filter as a change in resonance frequency, Irradiates light and measures its transmittance.
r) (for example, trade name: Heartridge type smoke meter) and the like have been developed.

However, in these means,
SOF and D.S. S cannot be measured separately from S, and there are problems such as insufficient correlation with a generally used filter collection / balance weighing method.

On the other hand, the applicant of the present application has filed Japanese Patent Application No. Hei.
No. 231194, Japanese Patent Application No. 3-231195, etc. eliminate the disadvantages of the above-mentioned prior art. S, sulfa
We have filed an application for a useful continuous particulate analyzer that can separate te for continuous quantitative analysis.

FIG. 2 schematically shows the structure of a particulate continuous analyzer proposed in the aforementioned Japanese Patent Application No. 3-231194. In this figure, reference numeral 1 denotes exhaust gas from a diesel engine (sample gas S ₀ ). Is a reference gas flow path branched at a point A from the sample gas flow path 1. This reference gas passage 2, is provided with a filter holder 4 with a built-in collection filter 3, particulate matter contained in the sample gas S ₀ are collected here. The collection filter 3 is made of, for example, the same material as that used in the filter collection / balance weighing method or a material such as quartz or Teflon (trade name) having few impurities. Reference numeral 5 denotes a filter holder (dummy) having the same volume as the filter holder 4 installed in the sample gas channel 1 in order to make the delay time the same as that of the reference gas channel 2, and a filter is mounted in the filter holder 5. It has not been.

Reference numeral 6 denotes a heating and burning furnace, for example, an electric resistance furnace or the like. The inside of the furnace is maintained at a constant temperature by a controller (not shown). For example, it is configured so that heating can be performed up to about 1000 ° C. Reference numeral 7 denotes a gas analyzer of a difference measurement method for detecting combustion gas that has passed through the heating furnace 6. Numerals 8 and 9 denote flow control valves for controlling the flow rates of the gas flowing through the sample gas flow path 1 and the reference gas flow path 2 to be constant, for example, mass flow controllers. Reference numeral 10 denotes a bypass pump. Reference numeral 11 denotes a flow path for discharging the gas from the gas analyzer 7. The discharge flow path 11 is provided with a critical flow venturi 12 and a discharge pump 13 connected in series.

[0010] The gas analyzer 7 of the difference measurement method is shown in FIG.
As shown in the figure, for example, infrared light sources 16 and 17 are arranged on one side of the sample gas cell 14 and the reference gas cell 15 having optical paths independent of each other, and H ₂ O, CO ₂ , SO ₂ are arranged on the other side. H ₂ O detector 18, CO ₂ detector 19, and SO ₂ detector 20, which are, for example, condenser microphone type detectors for simultaneously detecting a plurality of gases such as ₂ , are optically arranged in series with each other. ing. An optical modulation chopper 21 is provided between the cells 14 and 15 and the light sources 16 and 17 and is configured to be rotated by a driving mechanism (not shown). 22 is each detector 18, 1
A preamplifier for amplifying the output signals from 9, 20;
Reference numeral 23 denotes an arithmetic circuit for arithmetically processing the gas concentration as an output signal, and reference numeral 24 denotes a display for displaying the gas concentration.

In the particulate continuous analyzer having the above structure, half of the sample gas S ₀ flowing through the sample gas flow path 1 is diverted to the reference gas flow path 2 at the point A and passed through the collection filter 3. At this time, the contained particulates are removed to become a reference gas R ₁ and introduced into the heating and burning furnace 6. Then, the remaining half of the sample gas S ₁ passes through the dummy filter holder 5 as it is, and is similarly introduced into the heating furnace 6.

The inside of the heating and burning furnace 6 is, for example, 100
Heated to about 0 ° C., the C and SOF (HC) components are oxidized (combusted) to CO ₂ and H ₂ O, and the S component is thermally decomposed to SO ₂ .

The component of the sample gas S ₀ in FIG.
O ₂ , H ₂ O, SO ₂ and particulates (DS
+ SOF + SO ₃ ), and the sample gas S ₁ that has passed through the dummy filter holder 5 is a similar component. on the other hand,
Since the particulates of the reference gas R ₁ that has passed through the trapping filter 3 are removed by the trapping filter 3, the components thereof are CO ₂ , H ₂ O, and SO ₂ .

Both gases S ₁ and R ₁ are heated in an oxygen furnace, and the particulates in the sample gas S ₁ [D.
[S (C) + SOF (HC) + SO ₃ ] is oxidized and decomposed and gasified to form CO ₂ , H ₂ O, and SO ₂ ,
Reference gas R ₁ does not change since particulates have already been removed. Thus, the sample gas S ₂ in FIG. 2 includes a number of CO _2, H ₂ O, the SO ₂ from the reference gas R ₂ in FIG.

[0015] Then, since measuring the difference of the analysis unit in the 7 sample gas S ₂ and the reference gas R _2, particulates contained in the sample gas S ₁ [D. S + S
OF + SO ₂ ] is oxidized and thermally decomposed to produce CO ₂ and H ₂
The analyzer 7 indicates only O and SO ₂ . Therefore, the weight concentration of particulates (DS, SOF, S) can be calculated by using the analysis method of the present invention.

The combustion gas in the two gas passages 1 and 2 is sucked at the same flow rate by the action of the flow control valves 8 and 9, and the critical flow venturi 12 and the discharge pump 13 supply the sample gas at a constant flow rate. 1
4 and the reference gas cell 15.

The infrared light emitted from the light sources 16 and 17 shown in FIG. 3 is absorbed in the cells 14 and 15 in accordance with the respective gas concentrations, and then the H ₂ O detector 18 and the CO ₂ detector 19 are used. ,
The light is incident on the SO ₂ detector 20. H ₂ O in the sample gas S ₂ and the reference gas R ₂ Prefecture, CO _2, SO ₂
Density difference of each gas (e.g. H ₂ in the sample gas S ₂
Difference in concentration between O and H ₂ O in reference gas R ₂ . CO
₂ and SO ₂ . ) Are detected, and based on these concentrations, SOF, D.E. The S and S components can be quantitatively analyzed as weight.

As described above, according to the particulate continuous analyzer, the gas (H ₂ O, CO ₂ , CO ₂ , CO ₂ , CO ₂₎ generated by oxidizing and decomposing the particulates in the sample gas S ₁ line in the heating combustion furnace 6. SO ₂ ) The difference between the concentrations is represented by SOF, D.S. It can be continuously measured as S, S component weight,
In addition, the measurement can be performed in a short time without a skilled person.

[0019]

By the way, attempts have been made to treat exhaust gas from a diesel engine or the like using a catalyst or the like. The composition of the exhaust gas downstream of the catalyst differs depending on the combination of the exhaust gas and the catalyst for treating the exhaust gas.

According to the present inventors, depending on the combination of the exhaust gas and the catalyst, the case where the particulates contained in the exhaust gas are composed of carbon, hydrocarbon and sulfur, and the case where hydrocarbon and sulfate with crystallization water In some cases, it was found that the reaction formulas when combusted were different, and that the arithmetic processing had to be changed.

The present invention has been made in consideration of the above-mentioned matters, and its object is to adjust the concentration of each of the constituent components according to the structure of the particulates contained in the sample gas.
That is, an object of the present invention is to provide a particulate continuous analysis method that can reliably determine the concentrations of carbon, hydrocarbons, sulfur, sulfate with water of crystallization, and the like, and the concentration of the entire particulate.

[0022]

In order to achieve the above object, a method for continuous particulate analysis according to the present invention comprises a sample gas flow path through which a sample gas flows, and a branch from the sample gas flow path. A reference flow path comprising a filter for collecting particulates contained in the sample flow path, a heating combustion furnace for heating the sample gas and the reference gas flowing through the reference flow path, and a combustion gas passing through the heating combustion furnace And a difference analyzer for analyzing the H ₂ O concentration, the difference in CO ₂ concentration, and the difference in SO ₂ concentration in the sample gas and the reference gas, which are included in the sample gas. When it is determined that the particulates are composed of carbon, hydrocarbons and sulfur, mC + n _{H y + pS + qO 2 →} (m + n) CO 2 + (ny / 2) H 2 O + pSO 2 + q'O 2 [where the y is the molar ratio of carbon and hydrogen constituting the hydrocarbon (y = H / C), q , Q ′ is the number of moles of excess O ₂ with respect to m, n, p], the respective concentrations of carbon, hydrocarbon, sulfur and particulates in the sample gas are determined. When it is determined that the contained particulates are composed of hydrocarbons and sulfates with water of crystallization, mCH _y + nSO ₄ .xH ₂ O + pO ₂ → mCO ₂ + (my / 2 + xn) H ₂ O + nSO ₂ + p′O ₂ [where y is the molar ratio of carbon and hydrogen constituting hydrocarbons (y = H / C), and p and p 'are the number of moles of excess O ₂ with respect to m and n]. Hydrocarbons, sulfates with water of crystallization and putty in gas It is to obtain the respective concentration of curated.

[0023]

The constituents of the particulates contained in the sample gas are known in advance by the combination of the fuel and the catalyst. Thus, carbon,
Depending on the case where it is composed of hydrocarbon and sulfur and the case where it is composed of hydrocarbon and sulfate with water of crystallization, by applying appropriate treatment methods, the concentration of each component and the total concentration of particulates can be continuously Quantitatively and accurately.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the structure of an apparatus for carrying out the method of the present invention. In this figure, reference numeral 25 denotes a dilution tunnel to which an exhaust pipe 27 of a vehicle 26 is connected via an inlet pipe 28. Dilution air A is supplied from the upstream side, and the downstream side is connected to a suction pump (not shown). Reference numeral 29 denotes a sampling pipe provided on the downstream side of the dilution tunnel 25, and on the downstream side thereof, the particulate continuous analyzer 30 shown in FIG. 2 is provided. That is, the apparatus used in the method of the present invention is not different from the apparatus shown in FIGS.

Next, a description will be given of a formula for calculating the concentration of each component of the particulate and the concentration of the entire particulate.

I. Particulate is D. When composed of S (dry soot), SOF (hydrocarbon) and S (sulfur) In this case, the unit volume (1 m ³ , 20 ° C., 760 m
mHg) per mole of carbon, nmol of hydrocarbon, p
The reaction equation when the mole of sulfur is burned (oxidized) is represented by the following equation. mC + nCH _y + pS + qO ₂ → (m + n) CO ₂ + (ny / 2) H ₂ O + pSO ₂ + q′O ₂ (I) where y is the molar ratio of carbon to hydrogen (y
= H / C), and q and q ′ are the number of moles of excess O ₂ with respect to m, n and p.

The concentrations of the generated CO ₂ , H ₂ O, and SO ₂ (hereinafter, for example, represented by [CO ₂ ]) are as follows. [CO ₂ ] = 24.04 (m + n) (1 / m ³ ) (1) [H ₂ O] = 24.04 ny / 2 (1 / m ³ ) (2) [SO ₂ ] = 24 .04p (l / m ³ ) (3) Here, 24.04 represents an ideal gas volume (1 / mol) at 20 ° C. and 1 atm.

The concentrations of the constituents of the particulates are such that the atomic weights of H, C and S are 1.008, 12.
011 and 32.066, it is expressed as follows. [D. S] = 12.011 m (g / m ³ ) (4) [SOF] = 12.011n + 1.008 ny (g / m ³ ) (5) [S] = 32.066 p (g / m ³ ) ...... (6)

Therefore, the unit of the particulate concentration is m
Assuming g / m ³ and the unit of the generated gas concentration as ppm, the following equations are obtained from the above equations (1) to (3). [D. S] = ([CO ₂ ] − (2 / y) [H ₂ O]) × 12.0011 / 24.04 (mg / m ³ ) (7) [SOF] = 2 (12.0011 + 1.008y) ) [H ₂ O] ^{/24.04y (mg / m 3) ......} (8) (S) = 32.066 [SO _2] ^{/24.04 (mg / m 3) ......} (9) Then, the total [PM] = [D. S] + [SOF] + [S] = {12.0011 [CO ₂ ] +2.016 [H ₂ O] +32.066 [SO ₂ ]} / 24.04 (mg / m ³ ) (10) Becomes

II. When the particulates are composed of SOF (hydrocarbon) and nSO ₄ .xH ₂ O (sulfate with crystals), in this case, the unit volume (1 m ³ , 20 ° C., 76
A reaction formula when combustion (oxidation) of nmol hydrocarbons and nmol of sulfate with crystals per 0 mmHg is represented by the following equation. mCH _y + nSO ₄ .xH ₂ O + pO ₂ → mCO ₂ + (my / 2 + xn) H ₂ O + nSO ₂ + p′O ₂ (II) where y is a molar ratio of carbon to hydrogen constituting SOF (y
= H / C) and is, also, p, p 'is m, the number of moles of excess O ₂ for n, and, x is the number of moles of water contained in the sulfate.

The concentrations of generated CO ₂ , H ₂ O and SO ₂ are as follows. [CO ₂ ] = 24.04 m (1 / m ³ ) (11) [H ₂ O] = 24.04 (my / 2 + xn) (1 / m ³ ) (12) [SO ₂ ] = 24 .04n (l / m ³ ) (13)

The concentrations of the constituents of the particulate are expressed as follows. [D. S] = 0 (g / m ³ ) (14) [SOF] = 12.011 m + 1.008 my (g / m ³ ) (15) [SO ₄ ^-2 × H ₂ O] = 96.062n + 18. 015xn (g / m ³ ) (16)

From the above equations (11) to (16), the following equations are obtained. [SOF] = (12.0011 + 1.008y) [CO ₂ ] /24.04 (mg / m ³ ) (17) [SO ₄ ^-2 × H ₂ O] = (96.062 + 18.015x) [SO _2] / 24.04 = {96.062 [SO _2] Tasu18.015 ([H ₂ O] - (y / 2) [CO ^{_2])} /24.04 (mg / m 3} ) ...... (18 ) X = {[H ₂ O] − (y / 2) [CO ₂ ]} / [SO ₂ ] (19) Then, the total particulate concentration [PM] is expressed as [PM] = [D. S] + [SOF] + [SO ₄ ^-2 · xH ₂ O] = {(12.011-7.9995y) [CO _2] Tasu96.062 [SO _2] Tasu18.015 [H ₂ O]} / 24 .04 (mg / m ³ ) ... (20)

Therefore, when it is determined that the particulates contained in the sample gas are composed of carbon, hydrocarbon and sulfur, the above formulas (1) to (10) are used, and When it is determined that the contained particulates are composed of hydrocarbons and sulfates with water of crystallization, the above formulas (11) to (20) are used to determine the constituent components of the particulates. Each concentration and the total concentration of particulates can be quantified continuously and accurately.

In practice, for example, the above (1) to
By separately using the processing floppy storing the calculation formulas up to (10) and the processing floppy storing the calculation formulas (11) to (20), the calculation in each of the above cases can be performed.

[0037]

As described above, the present invention performs processing corresponding to the constituents of particulates, so that the concentration of each constituent of the particulates and the total concentration of the particulates can be continuously and continuously increased. It can be quantified with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of an apparatus for carrying out a method of the present invention.

FIG. 2 is a diagram showing an example of a particulate continuous analyzer used in the device.

FIG. 3 is a diagram showing an example of a configuration of a gas analyzer in the particulate continuous analyzer.

[Explanation of symbols]

1 ... Sample gas channel, 2 ... reference channel, 3 ... filter, 6 ... heat the combustion furnace, 7 ... analyzer, 30 ... particulate continuous analyzer, S _0, S _1, S ₂ ... sample gas, R ₁ , R ₂ ... reference gas.

Continuation of the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 31/12 G01N 21/61 G01N 31/00 G01N 15/06 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A sample gas flow path through which a sample gas flows, a reference flow path branched from the sample gas flow path and provided with a filter for collecting particulates contained in the sample gas, Sample and reference gas by a particulate continuous analyzer comprising a heating furnace for heating the sample gas and the reference gas flowing through the passage and the reference flow path, and an analyzer for analyzing the combustion gas passing through the heating furnace. The difference in H ₂ O concentration, the difference in CO ₂ concentration, and the difference in SO ₂ concentration in the above-mentioned method are obtained. When it is determined that the particulates contained in the sample gas are composed of carbon, hydrocarbon and sulfur, mC + nCH _{y + pS + qO 2 → (} m + n) CO 2 + (ny / 2) H 2 O + pSO 2 + q'O 2 [where Said y is the molar ratio of carbon and hydrogen constituting the hydrocarbon (y = H / C), q, q ' , based m, n, the number of moles of excess O _2] for p, the sample gas in When it is determined that the concentrations of carbon, hydrocarbons, sulfur and total particulates are determined. On the other hand, when it is determined that the particulates contained in the sample gas are composed of hydrocarbons and sulfates with water of crystallization, mCH _y + nSO ₄ .xH ₂ O + pO ₂ → mCO ₂ + (my / 2 + xn) H ₂ O + nSO ₂ + p′O ₂ [where y is the molar ratio of carbon to hydrogen constituting the hydrocarbon (y = H / C); p, p 'is characterized m, based n, the number of moles of excess O _2] for a hydrocarbon in the sample gas, that it has to determine the respective concentration of the crystal water with sulphates and total particulate matter Continuous analysis Law.