JP2010223650A - Method and instrument for measuring component in exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring the component in exhaust gas capable of specifying the target component in the exhaust gas on the basis of the concentration of a predetermined compound, which is formed by accelerating the reaction of the component in the exhaust gas of an internal combustion engine, regardless of simple apparatus constitution, and an instrument for measuring the component in the exhaust gas. <P>SOLUTION: An aqueous urea jet device 15 for supplying aqueous urea to the exhaust gas and a sampling probe 16 provided with a sampling hole 17 for sampling the exhaust gas are successively arranged along an exhaust gas flowing direction on the upstream side of the SCR catalyst 13 in the exhaust gas flowing direction and a sampling pipe 18 communicates with the sampling probe 16. The temperature of the sampled exhaust gas is regulated by the sampling pipe 18 to measure the concentration of ammonia in the exhaust gas regulated to a desired temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust gas component measuring method and an exhaust gas component measuring device for measuring components in exhaust gas discharged from an internal combustion engine.

Conventionally, exhaust gas analyzing apparatus for analyzing the gas discharged from the engine are known, it is generally possible to measure the nitrogen compounds such as NO _x and ammonia. This apparatus can also generally measure the urea concentration.

  Various methods for measuring the concentration of urea contained in a liquid are known as methods for measuring the urea concentration (see, for example, Patent Documents 1 and 2).

Further, in the exhaust process of a diesel engine (NO _x purification), for example, urea SCR (Selective Catalytic Reduction: Selective Catalytic Reduction) system has been effective, in recent years are available mounted to the track or the like. This system generates ammonia (NH ₃ ), which is a reducing agent for NO _x , by injecting urea water through thermal decomposition and hydrolysis reaction of the injected urea, and supplies this to the SCR catalyst. It has carried out _the NO _x purification.

JP 2003-247965 A JP 2008-233005 A

However, in terms of NO _x purification performance, it is not yet sufficient, and in order to make the catalyst function more efficiently, it is desired to supply a homogeneous reducing agent to the catalyst.

  In an exhaust pipe connected to an internal combustion engine such as an engine, in a reaction from injection of urea water to generation of ammonia, for example, when sampling an atmosphere in a certain region and measuring urea concentration, separately from the ammonia concentration measuring device, A urea measuring device is required. In addition, measurement methods such as liquid chromatography are generally used for urea analysis, and it is actually difficult to perform real-time measurement using such a method.

  The present invention has been made in view of the above, and based on a predetermined compound concentration generated by promoting the reaction of components in the exhaust gas of an internal combustion engine, while having a simple device configuration (for example, in real time). An object of the present invention is to provide an exhaust gas component measuring method and an exhaust gas component measuring device capable of quantifying a target component in exhaust gas, and to achieve the object.

  According to the present invention, according to a method for identifying a component in exhaust gas from a predetermined product produced by reaction from a component in exhaust gas, the specific component in continuously discharged gas can be grasped (for example, in real time) The device has also been obtained based on the knowledge that it has a simple configuration capable of detecting a predetermined product.

  In order to achieve the above object, an exhaust gas component measuring method according to a first aspect of the present invention includes an exhaust gas sampling process for sampling exhaust gas exhausted from an internal combustion engine and a reaction of components in the collected exhaust gas. A reaction promoting step promoted by the promoting means, a concentration measuring step for measuring the concentration of the product produced by the reaction, and a concentration for obtaining the concentration of at least the component in the exhaust gas based on the measured concentration The acquisition process is provided.

  In the first invention, when the concentration of the desired component in the exhaust gas is determined, the desired product is generated by promoting the reaction of the desired component, and the concentration is used as a standard, which is indispensable conventionally. This eliminates the need to measure multiple types of compounds, and eliminates the need to wait for the next sample for multiple types of measurements at the time of product quantification. In addition to being able to grasp, other than the target product, it can be configured using a simple device that is not suitable for measurement. In addition, the measurement accuracy can be kept high even in a system in which measurement variations are likely to occur due to, for example, accumulation in piping.

  As the reaction promoting means of the first invention, a temperature adjusting means for adjusting the exhaust gas to a predetermined temperature or a catalyst can be used.

  For example, when the reaction promoting means is configured using a temperature adjusting means for adjusting the exhaust gas to a predetermined temperature, in the concentration measurement step, when the temperature is adjusted to one predetermined temperature or two or more predetermined temperatures. It is possible to measure the product concentration in the exhaust gas. For example, when the reaction progress of the desired component in the exhaust gas changes depending on the temperature, the concentration of the desired component is measured for each temperature, and the concentration of the desired component in the exhaust gas can be obtained from a plurality of obtained measurement data. it can.

Specifically, the measurement is performed as follows when urea is supplied to the exhaust gas from the internal combustion engine. In this case, the exhaust gas component measuring method according to the first invention is
A urea supply step of supplying at least urea to the exhaust gas discharged from the internal combustion engine, an exhaust gas sampling step of sampling at least a predetermined sampling point of the exhaust gas supplied with urea, and a predetermined amount of the collected exhaust gas A temperature adjusting step for adjusting the temperature and promoting the reaction of the supplied urea, and an ammonia concentration C ₁ , ammonia and isocyanate in the exhaust gas adjusted to a temperature T ¹ that is equal to or lower than a temperature at which the ammonia generation reaction proceeds The ammonia concentration C ₂ in the exhaust gas adjusted to the temperature T ^{2 at} which the production reaction proceeds, and the ammonia concentration C _{2 in} the exhaust gas adjusted to the temperature T ^{3 at} which the ammonia production reaction from the isocyanic acid proceeds. ₃ and ammonia concentration measurement step of measuring the urea by the following formula 1 formula 2 from the measured the ammonia concentration was, isocyanic acid, A concentration acquisition step of acquiring the concentration of the fine ammonia, may be configured to provided.
Urea concentration = C ₂ -C ₁ Formula 1
Isocyanic acid concentration = C ₃ -C _2- (C ₂ -C ₁ ) Formula 2

In this case, urea is used as a desired component, and the thermal decomposition reaction and hydrolysis reaction of urea are promoted as shown in the following reaction formula to produce ammonia as a target product.
(NH ₂ ) ₂ CO → NH ₃ + HNCO (a)
HNCO + H ₂ O → NH ₃ + CO ₂ (b)

The “temperature T ¹ below the temperature at which the ammonia production reaction proceeds” is basically a temperature region before the reaction (a) proceeds. That is, the ammonia concentration C ₁ is a sampling point, refers to the ammonia concentration contained in exhaust gas in circulation.

In the first aspect of the present invention carried out by supplying the urea, after measuring the ammonia concentration C ₁ in the gas atmosphere in first reaction temperature T ¹ of progression of the temperature following start to actively progressed in (a), raising the temperature of exhaust gas Then, the reaction (a) is allowed to proceed completely under a gas atmosphere at a temperature T ² to generate ammonia and isocyanic acid from urea and measure the ammonia concentration C ₂ . Furthermore, by utilizing the moisture in the gas is allowed to proceed reaction (b) in a gas atmosphere which has a high temperature of the temperature T ^3, to measure the ammonia concentration C ₃ in the exhaust gas. Based on these ammonia concentrations, the concentrations of urea, isocyanic acid, and ammonia in the exhaust gas are obtained by the equations 1 and 2. In this way, the concentration of each component can be quantified, and the homogeneous reducing agent can be supplied to the catalyst easily (preferably in real time). As a result, it becomes possible to make the catalyst function more efficiently.

When urea is used as a desired component in the exhaust gas as described above and ammonia is measured as a target product, the temperature T ^{1 is set} to 100 ° C. or more and 150 ° C. or less, and the temperature T ² is set to more than 150 ° C. and 160 ° C. below ^{(150 ℃ <T 2 ≦ 160} ℃) and, suitably performed by the temperature ^{T 3} to a temperature in excess of 160 ° C.. Urea is promoted to decompose at a temperature exceeding 150 ° C., and is decomposed to ammonia and isocyanic acid at about 160 ° C., and further to 160 ° C., hydrolysis of isocyanic acid is promoted. For example, ammonia can be obtained from all of the isocyanic acid at 300 ° C.

  An exhaust gas component measuring apparatus according to a second aspect of the present invention includes an exhaust gas collecting means for collecting exhaust gas discharged from an internal combustion engine, a reaction promoting means for promoting the reaction of components in the collected exhaust gas, and the above reaction. Concentration measuring means for measuring the concentration of the produced product and concentration acquisition means for acquiring the concentration of the component in the exhaust gas based on the measured concentration are provided.

In the second invention, when the concentration of the desired component in the exhaust gas is determined, the desired product is generated by promoting the reaction of the desired component, and the concentration is used as a standard, which is indispensable conventionally. A device for measuring a plurality of types of compounds is not required, and waiting for measurement of the next sample is not required for a plurality of types of measurements at the time of product quantification. Thus, the desired component in the exhaust gas can be grasped (for example, in real time), and other than the target product can be configured using a simple device not suitable for measurement. In addition, the measurement accuracy can be kept high even in a system in which measurement variations are likely to occur due to, for example, accumulation in piping.
The reaction promoting means in the second invention can be a temperature adjusting means for adjusting the exhaust gas to a predetermined temperature, or a catalyst, as in the first invention.

  For example, when the reaction promoting means is configured by using a temperature adjusting means for adjusting the exhaust gas to a predetermined temperature, the concentration measuring means is used when the temperature is adjusted to one predetermined temperature or two or more predetermined temperatures. It is possible to measure the product concentration in the exhaust gas. For example, when the reaction progress of the desired component in the exhaust gas changes depending on the temperature, the sampled exhaust gas is adjusted by the temperature adjusting means, and the desired component concentration is measured by the concentration measuring means for each temperature. The concentration of the desired component in the exhaust gas is acquired from the plurality of measurement data using the concentration acquisition means.

For example, when measuring by supplying urea to the exhaust gas from an internal combustion engine, it can comprise as follows. In this case, the exhaust gas component measuring apparatus according to the second invention is
Urea supply means for supplying at least urea to the exhaust gas discharged from the internal combustion engine, exhaust gas collection means for collecting the exhaust gas supplied with at least urea at a predetermined sampling point, and the collected exhaust gas supplied And a temperature adjusting means for promoting the reaction of urea by adjusting the temperature of the supplied exhaust gas to a predetermined temperature, and ammonia in the exhaust gas adjusted to a temperature T ¹ which is not higher than a temperature at which the ammonia generation reaction proceeds. The concentration C ₁ , the ammonia concentration C ₂ in the exhaust gas adjusted to the temperature T ^{2 at} which the formation reaction of ammonia and isocyanic acid proceeds, and the temperature T ^{3 at} which the ammonia formation reaction from the isocyanic acid proceeds were adjusted. the ammonia-concentration measuring means for measuring the ammonia concentration C ₃ in the exhaust gas and, measured following formula 1 formula 2 from the ammonia concentration More urea, a concentration acquisition means for acquiring a concentration of isocyanic acid and ammonia, may be a structure provided with.
Urea concentration = C ₂ -C ₁ Formula 1
Isocyanic acid concentration = C ₃ -C _2- (C ₂ -C ₁ ) Formula 2

  In this case, urea is used as a desired component, and as shown in the reaction formulas (a) to (b), the thermal decomposition reaction and hydrolysis reaction of urea are promoted, and ammonia is generated as a target product. As above, the concentration of each component can be measured based on the ammonia concentration, and a method for supplying a homogeneous reducing agent to the catalyst can be studied by improving the urea water injection method, etc., and the catalyst can function more efficiently. Is possible.

  The exhaust gas collection means of the second invention preferably has a collection hole for collecting the exhaust gas at the collection point and can sample a desired exhaust gas.

  Further, a gas circulation pipe provided with a reaction promoting means is arranged between the exhaust gas collecting means constituting the second invention and the concentration measuring means, and the exhaust gas collecting means is provided by this gas circulation pipe. And the concentration measuring means can be configured to communicate with each other. The exhaust gas collected by the exhaust gas collecting means is temperature-adjusted in the path sent to the concentration measuring means, and the exhaust gas adjusted to a desired temperature can be introduced into the concentration measuring means as the test gas. .

INDUSTRIAL APPLICABILITY The present invention is useful for the development and construction of an optimum system for purifying exhaust gas and the like because it can measure and analyze desired components and reaction products in exhaust gas. For example, in a urea SCR system for exhaust gas treatment of a diesel engine (NO _x purification), urea, measured by separating the isocyanate and ammonia, it is useful to be able to analyze, thereby deposit a pipe in due like urea or isocyanic acid It is possible to construct a system suitable for exhaust gas purification while eliminating the influence of accumulation on the surface.

  According to the present invention, the target component in the exhaust gas is obtained (for example, in real time) while having a simple apparatus configuration based on the predetermined compound concentration generated by promoting the reaction of the component in the exhaust gas of the internal combustion engine. It is possible to provide an exhaust gas component measuring method and an exhaust gas component measuring apparatus capable of quantitatively determining the amount of exhaust gas.

It is sectional drawing which shows schematic structure of the exhaust gas component measuring apparatus which concerns on 1st Embodiment of this invention. It is a conceptual diagram for demonstrating the production | generation path | route which ammonia produces | generates from urea water. It is a conceptual diagram for demonstrating the method to calculate the density | concentration of urea and isocyanic acid. It is sectional drawing which shows schematic structure of the exhaust gas component measuring apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows schematic structure of the exhaust gas component measuring apparatus which concerns on 3rd Embodiment of this invention.

  Hereinafter, an embodiment of a method for measuring an exhaust gas component of the present invention will be described in detail with reference to the drawings, and an exhaust gas component measuring device will be described in detail through the description.

(First embodiment)
1st Embodiment of the measuring method of the waste gas component of this invention is described with reference to FIGS. In the urea SCR system used for diesel post-processing, the exhaust gas component measuring method of the present embodiment is a variable temperature controlled single sampling tube connected to a sampling probe provided upstream of the gas purification SCR catalyst in the exhaust gas flow direction. The ammonia concentration in the gas adjusted to a predetermined temperature is measured.

  In the present embodiment, as shown in FIG. 1, the purification device 12 is attached to the exhaust pipe 11 connected to the exhaust port of the diesel engine, and the exhaust gas flowing through the exhaust pipe 11 is supplied to the purification device 12. Has been purified. The purification device 12 includes an SCR catalyst 13 in a purification chamber having an inner diameter larger than the pipe diameter of the exhaust pipe 11.

  As the SCR catalyst 13, for example, a zeolite catalyst or a metal oxide catalyst such as alumina, zirconia, vanadia / titania can be used.

  On the upstream side of the SCR catalyst 13 in the exhaust gas flow direction (the arrow direction in FIG. 1) through which the exhaust gas flows, a urea water injection device 15 for supplying urea water to the exhaust gas, and sampling the exhaust gas (sampling) Sampling probe 16 is sequentially arranged along the exhaust gas flow direction so that when exhaust gas before urea supply or urea water is supplied, urea-containing exhaust gas can be sampled. Yes.

  As the urea water injection device 15, a known injection device such as an injector capable of spraying a liquid, performing shower injection, or the like can be used.

  The sampling probe 16 is a tubular pipe through which gas can flow. A sampling hole (collecting hole) 17 is provided at one end of the sampling probe 16 located in the purification device. The exhaust gas at a desired sampling point can be sampled from the sampling hole. As the piping shape of the sampling probe 16, it is possible to select an arbitrary shape such as a circular shape, an oval shape, or a rectangular cross-sectional shape, and the shape and size of the sampling hole are also selected according to the piping scale, gas flow rate, and the like. Can do.

  One end of a temperature-variable sampling pipe 18 is connected to the other end of the sampling probe 16 so that the temperature of the sampled exhaust gas (hereinafter also referred to as test gas) can be adjusted to a desired temperature. It has become. The length of the sampling tube 18 may be arbitrarily selected within a range in which the reaction (a) and (b) can sufficiently proceed, but the reaction time can be changed by adjusting the internal diameter of the sampling tube. May be sufficiently advanced. A heater 20 is arranged outside the sampling tube 18 so as to cover a part or the whole of the tube, and the sampling tube 18 is heated by the heater so that the temperature of the test gas can be adjusted. it can. A cooling fan for cooling the heated sampling tube may be attached.

  In addition to the heater, a sampling pipe (test gas) is provided on the outer wall surface of the sampling pipe 18 by arranging a heating medium circulation pipe that can circulate the heat medium and exchange heat with the heating medium. ) Temperature control can also be performed. In this case, it is possible to quickly heat and cool the test gas by controlling the temperature of the heating medium with a temperature control device (not shown).

The other end of the sampling pipe 18 is connected to an ammonia measuring device 30 for measuring the concentration of ammonia gas in the exhaust gas. The sampling probe 16 and the ammonia measuring device 30 are communicated with each other via the sampling tube 18, and the exhaust gas collected by the sampling probe 16 is temperature-controlled at a predetermined temperature by the sampling tube 18 and is ammonia measuring device 30. It is configured to be supplied to. The ammonia measuring device is a simple device having an ammonia analysis function.
The ammonia measuring device is not particularly limited, and any conventionally known device capable of measuring ammonia can be used.

  The ammonia measuring device 30 is electrically connected to the computer terminal 40, and the concentration value measured by the ammonia measuring device 30 is taken into the computer terminal at a desired timing, and urea, isocyanate, and Ammonia separation measurement is possible.

In the present embodiment, sampling of the test gas and temperature adjustment are performed as follows.
First, the exhaust gas (temperature T ⁰ ) supplied with urea water is sampled from a sampling hole 17 arranged at a desired sampling point (collecting point). At this time, since that does not cause ammonia formation reaction, the temperature of the sampling probe 16 is held in the T ¹ or less. Moreover, the said reaction (a) has already progressed and isocyanic acid and ammonia are contained. As shown in FIG. 2, the urea water injected by the urea water injection device 15 evaporates in the high-temperature exhaust gas, and urea, isocyanate, and ammonia are all present in the gas. This gas is sampled (temperature T ⁰ ) from the sampling hole 17 of the sampling probe 16 (temperature T ¹ or less). Next, when heated to 160 ° C. (temperature T ² ) in the sampling tube 18, urea is decomposed and ammonia and isocyanic acid are generated as in the reaction (a). Subsequently, when sampling is performed from the sampling hole 17 (temperature T ⁰ ) and the temperature of the sampling tube 18 is increased to 300 ° C. (temperature T ³ ) and heated, as shown in the reaction (b), isocyanic acid is decomposed and ammonia is removed. Generate. Thus, since reaction progress temperature of reaction (a) and (b) differs, the said reaction (a) or (b) can be selected by adjusting the temperature of test gas at the time of sampling.

After the desired temperature is selected and the temperature of the test gas is adjusted as described above, the test gas is introduced into the ammonia measuring device 30 connected at the other end of the sampling pipe 18. The ammonia measuring device 18 measures the ammonia concentration (C ₁ , C ₂ , C ₃ ) in the test gas for each temperature. The measured value is sent to the computer terminal 40 connected to the ammonia measuring device 30 and, for example, the component amount in the exhaust gas is acquired as follows.

The measurement of the ammonia concentration C ₁ , C ₂ , C ₃ will be specifically described with reference to FIG.
As shown in FIG. 3, first, exhaust gas into which urea water containing urea of a predetermined initial concentration is injected is sampled from the sampling hole 17 (at this time, the temperature of the sampling probe 16 is T It maintained ¹ below), which is introduced to the ammonia measuring device 30 through the sampling tube 18 as the gas to be detected (the temperature of the sampling tube 18 at this time is maintained at T ¹ below). At this time, for example, the temperature of T ¹ or lower is set to 130 ° C., and the ammonia concentration (ammonia concentration C ₁ ) is measured. Subsequently, the exhaust gas (temperature T ¹ ) sampled from the sampling hole 17 is heated to 160 ° C. (temperature T ² ) through the sampling pipe 18, and urea is completely decomposed into ammonia and isocyanic acid [urea concentration = 0 ( Zero)], and the concentration of ammonia in the test gas (ammonia concentration C ₂ ) is measured. At this time, the temperature of the sampling probe 16 may be a T ² even T ¹ or less. Further, the exhaust gas (temperature T ⁰ ) sampled from the sampling hole 17 is heated to 300 ° C. (temperature T ³ ) by the sampling pipe 18 to completely hydrolyze the isocyanate to ammonia and carbon dioxide, and then the test gas The concentration of ammonia (ammonia concentration C ₃ ) is measured. At this time, the temperature of the sampling probe 16 may be T ¹ or less or T ³ .
Then, utilizing the ammonia concentration obtained, as shown in FIG. 3, by subtracting from the ammonia concentration C ₁ and ammonia concentration C ₂ as shown in Equation 1, it is possible to determine the urea concentration at the sampling point . That is, when the temperature is raised to 160 ° C., the urea concentration becomes 0 (zero), and the difference in ammonia concentration between 130 ° C. and 160 ° C. becomes the urea concentration in the sampled exhaust gas. Further, the isocyanate concentration at the sampling point can be obtained by subtracting from the ammonia concentration C ₂ and the ammonia concentration C _{3 as} shown in the following formula 2.
Urea concentration = ammonia concentration _{C 2} - ammonia concentration _{C 1} · · Formula 1
Isocyanic acid concentration = ammonia concentration C ₃ -ammonia concentration C ₂ -urea concentration

In this way, by using a simple device that can only perform ammonia analysis as an analysis unit, the temperature of the sampling tube is adjusted and the ammonia concentration is measured for each temperature range, thereby measuring urea and isocyanate in the exhaust gas. Is possible.
In the above embodiment, the temperature is adjusted in the sampling tube 18. However, if necessary, the temperature of the sampling probe 16 may be adjusted by changing the sampling probe 16 itself to T ¹ and T ² , for example. Good. The sampling probe 16 may be constant ^{T 1} below.

Although the temperatures T ¹ for measuring the ammonia concentration C ₁ was 130 ° C., temperatures T ¹ is long the reaction (a) with ammonia is a difficult temperature region generated decomposed by pyrolysis of urea, the point It is preferably 100 ° C. or higher and 150 ° C. or lower. When the temperature is less than 100 ° C., ammonia is easily dissolved in water, and therefore, 100 ° C. or more is preferable. Although temperature T ² to measure the ammonia concentration C ₂ was 160 ° C., a temperature T ² are, as long the reaction (a) by a temperature region where the urea can be decomposed completely ammonia and isocyanic acid by thermal decomposition, 150 It is preferable that the temperature is over 160 ° C. and below. Although the temperature T ³ for measuring the ammonia concentration C ₃ and 300 ° C., a temperature T ^3, the the reaction (b) may be a temperature region where the isocyanate is completely hydrolyzed, exceed 160 ° C. It is preferable that it is 500 degrees C or less.

In the first embodiment described above, urea has been supplied to the exhaust gas and the ammonia concentration is measured. However, the method for measuring an exhaust gas component of the present invention is limited to the case where urea is used. However, as shown in the following formula, the present invention can be applied to the case where the chemical species are A, B, C,... And the number of moles is a, b, c,.
That is, only the chemical species A can be measured by the concentration measuring device or the like in the system of the atmosphere temperature T ¹ including a plurality of compounds aA, bB, cC,. When there is no concentration measurement technique or it is extremely difficult and these concentrations are unknown, the atmospheric temperature of the system is changed to a temperature T ² at which the chemical species B is completely converted (decomposed) into A, by measuring the number of moles a + .DELTA.a species a the ^(T 2 -T ¹⁾ in a concentration measuring apparatus or the like when, the number of moles of species B o'clock temperature ^{T 1} is a Δa ^(T 2 -T ¹⁾ Can be used to measure the concentration of the chemical species B. Further, the atmospheric temperature of the system is changed to a temperature T ³ at which the chemical species C is completely converted (decomposed) into the chemical species A, and the number of moles of the chemical species A at that time a + Δa (T ² −T ¹ ) + Δa ( By measuring T ³ -T ² ) with a concentration measuring device or the like, the chemical species C concentration at the temperature T ¹ becomes Δa (T ³ -T ² ). Can be measured. In addition, the same applies to an atmosphere including a plurality of types of dD, eE, fF.
In the above embodiment, the chemical species A corresponds to ammonia, the chemical species B corresponds to urea, and the chemical species C corresponds to isocyanate.

In the above-described embodiment, the example in which the temperature adjusting means for adjusting the exhaust gas to a predetermined temperature has been described as the reaction promoting means. However, in addition to the temperature adjusting means, other reaction promotion such as a method using a catalyst is used. It is possible to measure exhaust gas components in the same manner as described above by adopting means.
For example, as means for promoting the ammonia production reaction as described above, in addition to the means by temperature control, for example, 1) urea discharge by generating pulse discharge or alternating current discharge described in JP-A-2007-321680. A method using a plasma assist type urea reforming apparatus that converts ammonia into ammonia and extracting ammonia converted from urea, or 2) Tungsten oxide added to a titanium oxide carrier as described in JP-A-2006-122792 Urea hydrolysis catalyst having structure, 3) Titanium oxide based hydrolysis catalyst for converting urea water into ammonia, 4) Vanadium oxide or vanadium oxoacid salt as described in JP-A-2006-223937 For example, a method using a catalyst such as a urea decomposition catalyst may be used.

(Second Embodiment)
A second embodiment of the method for measuring exhaust gas components of the present invention will be described with reference to FIG. In the present embodiment, the single sampling tube of the first embodiment is branched into three, and the ammonia concentration at each temperature can be measured simultaneously.

  The SCR catalyst can be formed in the same manner as in the first embodiment using the material used in the first embodiment, and the same reference numerals are given to the same components as those in the first embodiment. Detailed description is omitted.

  As shown in FIG. 4, the measuring method of the exhaust gas component of the present embodiment is divided into three sampling common pipes 28 connected to the sampling probe 16, and the sampling pipes 51, 52, each capable of adjusting the temperature independently. 53 is provided. The exhaust gas sampled from the sampling hole 17 is supplied to each of the three sampling pipes 51, 52, 53, and the exhaust gas can be adjusted to different temperatures at the same time. At this time, the period from the sampling hole to the branch is configured to be kept at 100 to 150 ° C. so that the reaction (a) does not proceed while avoiding adsorption of ammonia to water.

  Note that the length of the sampling tubes 51, 52, 53 may be arbitrarily selected within a range in which the time required for the reactions (a) and (b) to sufficiently proceed is obtained, and the inner diameter of the sampling tubes may be adjusted. The residence time may be changed so that the reaction can proceed sufficiently. A heater 20 is disposed outside each sampling tube, and the temperature of the test gas can be adjusted by the heater as in the first embodiment. A cooling fan for cooling the heated sampling tube may be attached. In addition to the heater, it is also possible to arrange a heat medium circulation pipe capable of performing heat exchange as in the first embodiment. Similarly, the sampling probe 16 and the sampling common pipe 28 are also provided with heaters and heat medium circulation pipes, and it is necessary to keep the temperature from the sampling hole to the branch at 100 to 150 ° C.

The other ends of the sampling tubes 51, 52, 53 are connected to ammonia measuring devices 30a, 30b, 30c for measuring the concentration of ammonia gas in the exhaust gas, respectively. The sampling probe 16 and the ammonia measuring device 30a, 30b, or 30c are communicated with each other through different sampling pipes 51, 52, and 53, and exhaust gases collected by the sampling probe 16 are different among the three sampling pipes. The temperature is adjusted to a predetermined temperature and supplied to the ammonia measuring device. With such a configuration, for example, the collected exhaust gas (test gas) is temperature-controlled at 130 ° C. (temperature T ¹ or less) by the sampling pipe 51 and at the same time, 160 ° C. (temperature T ² ) by the sampling pipe 52. ) And at the same time, the sampling tube 53 is heated to 300 ° C. (temperature T ³ ), and the ammonia concentration (C ₁ , C ₂ , C ₃ ) is simultaneously measured by the ammonia measuring device connected to each sampling tube. It can be measured.
In the present embodiment, the reaction (a) or (b) can be selected by simultaneously adjusting the test gas to a plurality of temperatures. In this way, the target component in the exhaust gas can be quantified in real time while having a simple apparatus configuration.

  The ammonia measuring devices 30a, 30b, and 30c are electrically connected to one computer terminal 40, and the concentration values measured by each ammonia measuring device are collected at the computer terminal 40 at a desired timing, and the exhaust gas is discharged. In this configuration, separation and measurement of urea, isocyanic acid, and ammonia can be performed quickly.

By using the obtained ammonia concentration, the urea concentration at the sampling point is obtained by subtracting from the ammonia concentration C ₁ and the ammonia concentration C ₂ as shown in the above equation 1 as shown in FIG. 3 as in the first embodiment. Further, the isocyanate concentration at the sampling point is obtained by subtracting from the ammonia concentration C ₂ and the ammonia concentration C _{3 as} shown in the following formula 2.

Thus, also in this embodiment, by using a simple device that can only perform ammonia analysis as an analysis unit, the temperature of the three sampling tubes is adjusted separately, and the ammonia concentration is measured for each temperature region, Urea and isocyanic acid in exhaust gas can be measured.
In the above embodiments, although as to temperature control in three sampling tubes 51, 52, 53, the sampling probe 16, the sampling common tube 28, it is necessary to hold the T ¹ or less.

The temperatures T ¹ , T ² , and T ³ for measuring the ammonia concentration are the same as in the first embodiment, and this embodiment is also performed by supplying urea into the exhaust gas and measuring the ammonia concentration. It is not limited to cases. Further, in addition to the temperature adjusting means, other reaction promoting means such as a method using a catalyst can be employed to measure the exhaust gas component in the same manner as described above.

(Third embodiment)
A third embodiment of the method for measuring exhaust gas components of the present invention will be described with reference to FIG. In this embodiment, the single-tube sampling tube of the first embodiment is branched into three, the sampling gas is selected according to the desired temperature and the temperature is adjusted by selecting the sampling tube, and then the single-tube sampling tube is again used. It is set as the structure which measures ammonia concentration via this.

  The SCR catalyst can be formed by using the material used in the first embodiment in the same manner as in the first embodiment, and the same reference numerals are used for the same constituent elements as those in the first and second embodiments. The detailed description is omitted.

  As shown in FIG. 5, the measuring method of the exhaust gas component of the present embodiment is divided into three sampling common pipes 28 connected to the sampling probe 16, and the sampling pipes 51, 52, each capable of adjusting the temperature independently. 53 is provided. Valves V1, V2, and V3 are attached to the sampling pipes 51, 52, and 53, and the exhaust gas sampled from the sampling hole 17 is opened and closed in accordance with the regulated temperature, so that three gases are detected as test gases. It is supplied to one of the sampling tubes 51, 52 and 53 so that the temperature can be adjusted.

The sampling tubes 51, 52, 53 are connected to one end of a single sampling common tube 38 at the other end opposite to one end connected to the sampling common tube 28. The other end of the sampling common pipe 38 is connected to an ammonia measuring device 30 for measuring the concentration of ammonia gas in the exhaust gas. The sampling probe 16 and the ammonia measuring device 30 communicate with each other via the sampling common pipe 28, the sampling pipes 51, 52, 53, and the sampling pipe 38, and the exhaust gas collected by the sampling probe 16 includes three exhaust gases. After the temperature is adjusted to different predetermined temperatures in the sampling tubes, the temperature is supplied to the ammonia measuring device 30 through the sampling common tube 38. With such a configuration, for example, by opening the valve V1 and closing the valves V2 and V3, the sample gas 51 is temperature-controlled at 130 ° C. (temperature T ¹ or less), and the ammonia concentration C ₁ is measured. By opening the valve V2 and closing the valves V1 and V3, the test gas is heated to 160 ° C. (temperature T ² ) in the sampling pipe 52, and urea is completely decomposed into ammonia and isocyanic acid [urea concentration = 0 ( zero)], measuring the ammonia concentration C ₂ in the test gas. Further, by opening the valve V3 and closing the valves V1 and V2, the test gas is heated to 300 ° C. (temperature T ³ ) in the sampling pipe 53, and after the isocyanate is completely hydrolyzed to ammonia and carbon dioxide, it is possible to measure the ammonia concentration C ₃ in the test gas.

  At this time, the sampling common pipe 38 from the sampling hole to the branch and the single pipe is kept at 100 to 150 ° C. so that the reaction (a) does not proceed while avoiding adsorption of ammonia to water. It is configured as follows. The sampling probe 16 and the sampling common pipes 28 and 38 need to be kept at 100 to 150 ° C. by providing a heater and a heat medium circulation pipe as in the first embodiment.

  The ammonia measuring device 30 is electrically connected to the computer terminal 40, and the concentration value measured by the ammonia measuring device 30 is taken into the computer terminal at a desired timing, and urea, isocyanate, and Ammonia separation measurement is possible. Also in this embodiment, the reaction (a) or (b) can be selected by adjusting the test gas to a plurality of temperatures.

By using the obtained ammonia concentration, the urea concentration at the sampling point is obtained by subtracting from the ammonia concentration C ₁ and the ammonia concentration C ₂ as shown in the above equation 1 as shown in FIG. 3 as in the first embodiment. Further, the isocyanate concentration at the sampling point is obtained by subtracting from the ammonia concentration C ₂ and the ammonia concentration C _{3 as} shown in the following formula 2. Thus, also in this embodiment, by using a simple device that can only perform ammonia analysis as an analysis unit, the temperature of the three sampling tubes is adjusted separately, and the ammonia concentration is measured for each temperature region. Measurement of urea and isocyanic acid in exhaust gas is possible.

In this embodiment, the temperature is adjusted in the three sampling tubes 51, 52, and 53, but the temperature of the sampling probe 16 and the sampling common tubes 28 and 28 may be adjusted as necessary.
The temperatures T ¹ , T ² , and T ³ for measuring the ammonia concentration are the same as in the first embodiment, and this embodiment is also performed by supplying urea into the exhaust gas and measuring the ammonia concentration. It is not limited to cases. Further, in addition to the temperature adjusting means, other reaction promoting means such as a method using a catalyst can be employed to measure the exhaust gas component in the same manner as described above.

15 ... Urea water injection device 16 ... Sampling probe 17 ... Sampling holes 18, 51, 52, 53 ... Sampling tubes 28, 38 ... Sampling common tubes 30, 30a, 30b, 30c ...・ Ammonia measuring device

Claims (10)

An exhaust gas collecting step for collecting exhaust gas discharged from the internal combustion engine;
A reaction promoting step of promoting the reaction of components in the collected exhaust gas by a reaction promoting means;
A concentration measuring step for measuring the concentration of the product produced by the reaction;
A concentration acquisition step of acquiring a concentration of at least the component in the exhaust gas based on the measured concentration;
A method for measuring exhaust gas components.   The method for measuring an exhaust gas component according to claim 1, wherein the reaction promoting means is a temperature adjusting means for adjusting the exhaust gas to a predetermined temperature or a catalyst. The reaction promoting means is a temperature adjusting means for adjusting the exhaust gas to a predetermined temperature,
The method for measuring an exhaust gas component according to claim 1, wherein the concentration measuring step measures the concentration of the product in the exhaust gas adjusted to at least one predetermined temperature. And a urea supply step of supplying at least urea to the exhaust gas discharged from the internal combustion engine,
The exhaust gas collecting step collects at least a predetermined sampling point of the exhaust gas supplied with urea,
The reaction promoting step promotes the reaction of supplied urea by adjusting the collected exhaust gas to a predetermined temperature,
The concentration measuring step is adjusted to an ammonia concentration C ₁ in the exhaust gas adjusted to a temperature T ¹ that is equal to or lower than a temperature at which the ammonia production reaction proceeds, and a temperature T ² at which the ammonia and isocyanate production reaction proceeds. the ammonia concentration C ₂ of the exhaust gas and the on ammonia concentration C ₃ of the exhaust gas ammonia formation reaction is adjusted to a temperature T ³ which proceeds from the isocyanic acid is measured,
2. The method for measuring an exhaust gas component according to claim 1, wherein the concentration acquisition step acquires the concentrations of urea, isocyanic acid, and ammonia from the measured ammonia concentration according to the following formulas 1 and 2.
Urea concentration = C ₂ −C ₁ (Formula 1)
Isocyanic acid concentration = C ₃ -C _2- (C ₂ -C ₁ ) (Formula 2) The temperature T ¹ is 100 ° C. or higher and 150 ° C. or lower, the temperature T ² is higher than 150 ° C. and lower than 160 ° C., and the temperature T ³ is higher than 160 ° C. 5. Method for measuring exhaust gas components. Exhaust gas collecting means for collecting exhaust gas discharged from the internal combustion engine;
Reaction promoting means for promoting reaction of components in the collected exhaust gas;
Concentration measuring means for measuring the concentration of the product produced by the reaction;
A concentration acquisition means for acquiring the concentration of the component in the exhaust gas based on the measured concentration;
Exhaust gas component measuring device equipped with.   The exhaust gas component measuring apparatus according to claim 6, wherein the reaction promoting means is a temperature adjusting means for adjusting the exhaust gas to a predetermined temperature, or a catalyst. Furthermore, provided with upstream of the exhaust gas collecting means in the exhaust gas circulation direction, provided with urea supply means for supplying at least urea to the exhaust gas discharged from the internal combustion engine,
The exhaust gas sampling means collects the exhaust gas supplied with at least urea at a predetermined sampling point,
The reaction promoting means is a temperature adjusting means for promoting the reaction of the supplied urea by adjusting the collected exhaust gas to a predetermined temperature.
The concentration measuring means is adjusted to an ammonia concentration C ₁ in the exhaust gas adjusted to a temperature T ¹ that is equal to or lower than a temperature at which ammonia production reaction proceeds, and a temperature T ^{2 at} which ammonia and isocyanate production reaction proceeds. the ammonia concentration C ₂ of the exhaust gas was a ammonia-concentration measuring unit that ammonia formation reaction to measure the ammonia concentration C ₃ of the exhaust gas is adjusted to a temperature T ³ which proceeds from the isocyanate,
The said density | concentration acquisition means is an ammonia concentration acquisition means which acquires the density | concentration of urea, an isocyanic acid, and ammonia from the measured said ammonia density | concentration by the following formula 1-2 formula, It is characterized by the above-mentioned. Exhaust gas component measuring device.
Urea concentration = C ₂ −C ₁ (Formula 1)
Isocyanic acid concentration = C ₃ -C _2- (C ₂ -C ₁ ) (Formula 2)   9. The exhaust gas component measuring apparatus according to claim 6, wherein the exhaust gas sampling means has a sampling hole for sampling exhaust gas at a sampling point.   A gas flow pipe provided with the reaction promoting means is provided between the exhaust gas collecting means and the concentration measuring means, and the exhaust gas collecting means and the concentration measuring means are communicated by the gas flow pipe. The exhaust gas component measuring apparatus according to any one of claims 6 to 9, wherein

Images