JP2012002582A - Dew point measuring method and dew point measuring apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dew point measuring method that accurately measures the dew point of a gas using a dew condensation sensor that fits on a actual shape of the portion where condensation occurs.SOLUTION: The dew point of a gas to be measured is determined based on a signal from a dew condensation sensor 6 that detects condensation inside of a pipe 6 through which the gas to be measured flows and a signal from a temperature sensor that measures the temperature of the gas to be measured.

Description

  The present invention relates to a dew point measuring method and a dew point measuring apparatus using the dew point measuring method.

Conventionally, in a device that uses gas or a device that comes in contact with gas, condensation may occur on the wall surface due to a temperature difference between the wall surface temperature of the device in contact with the gas and the gas.
For example, in the case of an engine system in which the above equipment incorporates an exhaust gas recirculation system (hereinafter referred to as “EGR system” (see Patent Document 1)), in an intake side pipe that has taken in exhaust gas. Condensation may occur.
The exhaust gas contains nitrogen oxide (NOx) and sulfur oxide (SOx). For this reason, the dew condensation liquid generated as a result of dew condensation becomes a corrosive liquid, which may damage the piping.
For this reason, it is preferable that such a device with the possibility of condensation is obtained by calculating an operation condition that does not cause condensation and operates so as to satisfy the obtained condition.

JP 2000-008972 A JP-A-6-130013

By the way, for example, when a new engine system is assembled, the engine driving environment and piping installation environment change, and the composition of the exhaust gas changes. A change in the composition of the exhaust gas means a change in the dew point of the exhaust gas.
In order to grasp such a change in the dew point of the exhaust gas, for example, a method of analyzing the composition of the exhaust gas by gas chromatography or an optical measuring device and calculating the dew point of the exhaust gas based on the analysis result can be considered. (See Patent Document 2).
However, in such a method, since the dew point is calculated based on the analysis result of the gas chromatography or the optical measurement device, the calculation process is complicated, and an accurate dew point cannot be obtained.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a dew point measuring method for accurately measuring the dew point of a gas whose dew point is unknown and a dew point measuring apparatus using the dew point measuring method.

  The present invention adopts the following configuration as means for solving the above-described problems.

  1st invention is a dew point measuring method which measures the dew point of measurement object gas, Comprising: The signal from the dew condensation sensor which detects the dew condensation in piping in which the measurement object gas flows, and the temperature of the measurement object gas are measured A configuration is adopted in which the dew point of the measurement target gas is obtained based on the signal from the temperature sensor.

  A second invention adopts a configuration in which the dew point of the measurement object gas is obtained while adjusting the temperature of the pipe in the first invention.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the dew condensation sensor is shaped into a pipe shape having an internal flow path through which a fluid flows, and a plurality of conductive materials exposed to the internal flow path and the outer wall surface. A configuration is adopted in which a region and an insulating region that insulates the conductive regions from each other are provided.

  4th invention is a dew point measuring apparatus which measures the dew point of measurement object gas, Comprising: The dew condensation sensor which detects the dew condensation in the piping through which the said measurement object gas flows, The temperature sensor which measures the temperature of the said measurement object gas, A configuration is adopted in which a measurement unit for obtaining a dew point of the measurement target gas based on a signal from the dew condensation sensor and a signal from the temperature sensor is employed.

  ADVANTAGE OF THE INVENTION According to this invention, the dew point of measurement object gas can be calculated | required based on the signal from the dew sensor which detects the dew condensation in the piping through which measurement object gas flows, and the signal from the temperature sensor which measures the temperature of measurement object gas. Therefore, the dew point can be obtained in a state that matches the actual device. The obtained dew point information can be used for designing the device.

It is a schematic block diagram of a test apparatus using the dew point measuring method in one Embodiment of this invention. It is an external view of the dew condensation sensor used with the dew point measuring method in one Embodiment of this invention.

  Hereinafter, a dew point measuring method according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

  FIG. 1 is a schematic configuration diagram of a test apparatus T that performs dew point measurement using a dew point measurement method according to an embodiment of the present invention. The EGR system test apparatus T includes an EGR system, and includes an engine 1, a turbocharger 2, a temperature adjustment device 3, thermometers 4 a and 4 b, a measurement unit 5, and a dew condensation sensor 6.

The engine 1 is an internal combustion engine such as a gasoline engine or a diesel engine. The turbocharger 2 includes a compressor 2a on one side of a rotating shaft and a turbine 2b on the other side of the rotating shaft.
The compressor 2 a is connected to an intake pipe 7 connected to the intake side of the engine 1, and the turbine 2 b is connected to an exhaust pipe 8 connected to the exhaust side of the engine 1. A recirculation pipe 9 is connected to the intake pipe 7 and the exhaust pipe 8 so as to bypass the turbocharger 2. Further, a dew condensation sensor 6 is connected between a portion where the recirculation pipe 9 of the intake pipe 7 is connected and a place where the compressor 2a is installed. The condensation sensor 6 will be described in detail later with reference to the drawings.
In addition to the members shown in FIG. 1, the actual test apparatus T is provided with members such as an air cleaner and an intercooler, but are omitted here for the sake of simplicity.

  The temperature adjusting device 3 is provided on the outer periphery of the dew condensation sensor 6 and is configured to allow a heat medium made of gas or liquid to pass through. The dew sensor 6 is adjusted to a set temperature, and the inside of the dew condensation sensor 6 is adjusted. It is comprised so that the temperature of the flowing gas (measurement object gas) can be adjusted.

  The thermometers 4a and 4b are thermocouple thermometers, are arranged with the temperature adjusting device 3 and the dew condensation sensor 6 interposed therebetween, and are respectively attached to the intake pipe 7. The thermometers 4a and 4b measure the gas temperature in the intake pipe 7.

  Although not shown, the measurement unit 5 is a power supply circuit that supplies a predetermined voltage to the dew condensation sensor 6, an arithmetic processing circuit (CPU) that detects the presence or absence of dew condensation based on a current signal output from the dew condensation sensor, and the like. It is comprised including.

  The condensation sensor 6 will be described with reference to FIG. 2A is a front view of the dew condensation sensor 6, and FIG. 2B is a right side view thereof. The dew condensation sensor 6 includes conductor portions 10a, 10b, 10c, and 10d corresponding to the conductive regions of the present invention, and insulating portions 11a, 11b, 11c, and 11d corresponding to the insulating regions of the present invention.

  Each of the conductor portions 10a, 10b, 10c, and 10d is made of a conductive plate material such as SUS having an elongated outer shape, and the short side of the plate material is formed in an arc shape. The arcs of the conductor portions 10a, 10b, 10c, and 10d are circles having a predetermined diameter when the short sides of the conductor portions 10a, 10b, 10c, and 10d are arranged along the arc. It is determined to be present (see FIG. 2A). Therefore, when the short sides of the conductor portions 10a, 10b, 10c, and 10d are arranged along an arc, a cylinder having a length equal to the length of the long side of the plate material is formed (see FIG. 2B). .

  Each of the insulating portions 11a, 11b, 11c, and 11d is made of an electrically insulating plate material such as a synthetic resin having a long outer shape. The length is equal to the length of each of the conductor portions 10a, 10b, 10c, and 10d, and the width on the short side is sufficiently greater than the length of the arc-shaped short side of each of the conductor portions 10a, 10b, 10c, and 10d. It is small, and its height (thickness) is formed to be equal to the thickness of each conductor portion 10a, 10b, 10c, 10d. The width on the short side of each of the insulating portions 11a, 11b, 11c, and 11d is determined by the size of the dew condensation that is detected, and the smaller the width, the smaller the dew condensation can be detected.

The arrangement relationship of the conductor portions 10a, 10b, 10c, 10d and the insulating portions 11a, 11b, 11c, 11d is combined in an airtight state using an adhesive or the like so that the conductor portions and the insulating portions are alternated.
In other words, the insulating portion 11a has the longitudinal side surfaces of the conductor portions 10a and 10b in contact with both side surfaces in the longitudinal direction, and both end surfaces on the short side of the insulating portion 11a are short sides of the conductor portions 10a and 10b. Are provided so as to coincide with the both end faces.
Similarly, the insulating portion 11b is disposed between the conductor portions 10b and 10c, the insulating portion 11c is disposed on the conductor portions 10c and 10d, and the insulating portion 11d is disposed on the conductor portions 10d and 10a. Is done.
By arranging the conductor portions 10a, 10b, 10c, and 10d and the insulating portions 11a, 11b, 11c, and 11d, a pipe shape having an internal channel through which a gas fluid flows is formed.
In the present invention, the term “insulating region that insulates conductive regions” means a region that electrically insulates adjacent conductor portions.

  The cylindrical dew condensation sensor 6 comprising the conductor portions 10a, 10b, 10c, 10d and the insulating portions 11a, 11b, 11c, 11d has at least the cylindrical inner diameter shape of the dew condensation detection portion of the intake pipe 4 in FIG. It is determined to match the inner diameter shape. In FIG. 1, the dew condensation detection point is set at the straight line portion of the intake pipe 4, so that the inner diameter shape of the dew condensation sensor 6 is also formed in accordance with the straight line portion of the intake pipe 4. Therefore, when the dew condensation detection location is curved such as an elbow, it is formed in accordance with the curvature.

  The dew condensation detection principle of the dew condensation sensor 6 having the above configuration will be described with reference to FIG. Ammeters A1, A2, A3, and A4 are connected between the conductor portions 10a and 10b, between the conductor portions 10b and 10c, between the conductor portions 10c and 10d, and between the conductor portions 10d and 10a, respectively. These ammeters A 1, A 2, A 3, and A 4 are electrically connected to the measurement unit 5. Although not shown, a preset voltage from a power supply circuit (not shown) is sequentially applied between the conductor portions 10a and 10b, between the conductor portions 10b and 10c, between the conductor portions 10c and 10d, and between the conductor portions 10d and 10a. The

The inside of the dew condensation sensor 6 is kept in a state where the dew condensation liquid L is not generated prior to the dew condensation detection. This state is obtained by passing a dry gas containing no dew condensation component inside the dew condensation sensor 6.
Next, when a gas (corresponding to the “measurement target gas” in the present invention) flows inside the dew condensation sensor 6, the temperature generated when the gas contacts the inner wall surface of the dew condensation sensor 6. Condensation occurs under certain conditions such as a reduction, and a condensed liquid L is generated.

  When the generated condensed liquid L is present on the insulating portion 11a, the electrical insulation between the conductor portions 10a and 10b is broken, and a predetermined current value is displayed on the ammeter A1. Therefore, when the ammeter A1 detects a predetermined current value, it can be seen that the dew condensation liquid L is generated between the conductor portions 10a and 10b. Further, since the detected current value is known to be proportional to the size of the generated condensed liquid L, that is, the wet area, the size of the condensed liquid L can also be estimated from the current value.

  Similarly, the condensed liquid L generated on the insulating part 11b is detected by the ammeter A2, the condensed liquid L generated on the insulating part 11c is detected by the ammeter A3, and generated on the insulating part 11d. The condensed liquid L is detected by the ammeter A4.

In addition, although the direct current or alternating current can be selected as the power supply applied to each conductor part, in the case of an alternating current power supply, there exists a possibility that the liquid resistance of the dew condensation liquid L can be estimated from the measured impedance. Yes.
Further, in this example, a predetermined voltage is applied from each power source circuit to each conductor portion. However, the conductor portion is made of a dissimilar metal to form a galvanic pair, and supply of voltage is omitted. It may be. For example, the metal of the conductor portions 10a and 10c may be different from the metal of the conductor portions 10b and 10a.

  The dew condensation sensor 6 includes four conductor portions 10a, 10b, 10c, and 10d and four insulating portions 11a, 11b, 11c, and 11d, but includes four or more conductor portions and insulating portions. Can be configured. As these numbers increase, finer dew condensation detection becomes possible.

The installation position of the dew condensation sensor 6 shown in FIG. 1 is an example, and the dew condensation sensor S1 may be installed as a part of other piping. The configuration of the test apparatus T shown in FIG. 1 is also an example, and another apparatus configuration may be adopted.
And in this embodiment, the dew point measuring apparatus of this invention is comprised by the temperature control apparatus 3, the thermometer 4a, 4b, the measurement part 5, and the dew condensation sensor 6. FIG.

  In order to conduct the dew condensation detection experiment of the engine 1 using the test apparatus T having the above-described configuration, the engine 1 is driven to bypass the throttle valve V1 provided in the intake pipe 4 and the turbine 2b in the exhaust pipe 5. The opening degree of the valve (weight gate) V <b> 2 in the bypass path provided in this manner and the valve V <b> 3 provided in the recirculation pipe 6 is adjusted. Furthermore, the temperature of the dew condensation sensor 6 is set by adjusting the passing heat medium to the temperature adjusting device 3. This set temperature is performed assuming an environment such as a summer or winter season where the engine 1 is placed or a cold district specification (see “Piping temperature” in Table 1 described later).

When the engine 1 is driven by changing conditions such as the opening adjustment of each of the V1 to V3 and the temperature of the temperature adjusting device 3, the inner wall surface of the condensation sensor 6 has NOx contained in the exhaust gas, Corrosive liquids containing components such as SOx may condense. When it is detected that condensation has occurred, the temperature at that time is determined as the dew point of the gas flowing through the intake pipe 4.
Table 1 shows the presence or absence of condensation when the temperature of the condensation sensor 6 (“pipe temperature” in Table 1) is changed to a predetermined temperature for each type of fuel supplied to the engine 1, EGR rate, and combustion efficiency. Yes.

  As can be seen from Table 1, the dew point is 25 ° C. when the fuel is “A”, the EGR rate is 10% and the combustion efficiency is 80%, the fuel is “A”, the EGR rate is 20%, and The dew point at the operating condition of combustion efficiency of 70% is measured to be 50 ° C. Since the measured dew point can predict the correlation between the operating conditions and the risk of corrosion due to gas, it is possible to set an appropriate EGR rate. As shown in Table 1, it is preferable to obtain a wide range of dew point information for each EGR rate and fuel efficiency of other fuels (for example, “B” and “C”).

  According to the dew point measuring method and the dew point measuring apparatus of the present embodiment as described above, based on the signal from the dew sensor 6 that detects dew condensation in the pipe through which the gas flows and the signal from the temperature sensor 4a that measures the temperature of the gas. Thus, the dew point of the gas can be obtained, so that the dew point can be obtained in a state suitable for the actual equipment. The obtained dew point information can be used for designing the device.

  In the above dew point measurement method, the dew point of the measurement target gas is measured while adjusting the temperature of the dew condensation sensor 6. For this reason, it becomes possible to easily find the dew point of the measurement target gas.

The dew condensation sensor 6 used in the above dew point measurement method is set in a pipe shape having an internal flow path through which gas flows. For this reason, as described above, the dew condensation sensor 6 can be incorporated into a part of the piping of the test apparatus T to perform a test, and it is possible to accurately detect the presence or absence of dew condensation in an actual operation state.
Further, the conductor portions 10 a, 10 b, 10 c, and 10 d included in the dew condensation sensor 6 are exposed on the outer wall surface of the dew condensation sensor 6. For this reason, it is possible to connect the wiring from the outside of the dew condensation sensor 6, and it is possible to route the wiring without hindering the gas flow.

  Moreover, since the dew condensation sensor 6 of the said embodiment can connect a wiring further from the outer side of the dew condensation sensor 6, it is possible to make the diameter of an internal flow path extremely small in the range which does not obstruct | occlude. That is, the dew condensation sensor 6 of the above-described embodiment is suitable for downsizing, and it is possible to detect dew condensation in a small-diameter pipe that has not been able to detect dew condensation.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above-described embodiment, the configuration in which the dew condensation is detected using the pipe-shaped dew condensation sensor 6 has been described.
However, the present invention is not limited to this, and for example, an ACM sensor may be attached as a dew condensation sensor in the pipe to detect dew condensation in the pipe.

  T ... Test device, 1 ... Engine, 2 ... Turbocharger, 3 ... Temperature control device, 4a, 4b ... thermometer (dew point measuring device), 5 ... measuring unit (dew point measuring device), 6 ... ... dew condensation sensor (dew point measuring device), 7 ... intake pipe, 8 ... exhaust pipe, 9 ... recirculation pipe, 10a, 10b, 10c, 10d ... conductor part (conductive region), 11a, 11b, 11c, 11d: Insulation part (insulation region), A1, A2, A3, A4 ... Ammeter, L ... Condensation liquid

Claims (4)

A dew point measurement method for measuring a dew point of a measurement target gas,
Determining the dew point of the measurement target gas based on a signal from a dew condensation sensor that detects dew condensation in the pipe through which the measurement target gas flows and a signal from a temperature sensor that measures the temperature of the measurement target gas. Dew point measurement method.   The dew point measuring method according to claim 1, wherein the dew point of the measurement target gas is obtained while adjusting the temperature of the pipe. The dew condensation sensor
While being set to a pipe shape having an internal flow path through which the fluid flows,
The dew point measurement method according to claim 1, further comprising: a plurality of conductive regions exposed to the internal flow path and the outer wall surface, and an insulating region that insulates the conductive regions. A dew point measuring device that measures the dew point of the gas to be measured,
A dew condensation sensor for detecting dew condensation in the pipe through which the measurement target gas flows;
A temperature sensor for measuring the temperature of the measurement target gas;
A dew point measurement apparatus comprising: a measurement unit that obtains a dew point of the measurement target gas based on a signal from the dew condensation sensor and a signal from the temperature sensor.

Images