JPWO2010125998A1 - Steam measuring device - Google Patents

Abstract

Provided is a vapor measuring device that has a simple configuration and is less likely to be deteriorated due to dew condensation or the like, and that can measure a qualitative value or a measurement that can reproduce processing conditions. For this reason, the vapor measuring apparatus of the present invention is a vapor measuring apparatus having a moisture sensitive part formed of a porous material and a first sensor for measuring a temperature in the vicinity of the surface of the moisture sensitive part. The wet section includes a supply path for supplying water and a discharge path for discharging water from the moisture sensitive section.

Description

  The present invention relates to a vapor measuring apparatus capable of measuring a wide range of humidity (concentration of water vapor) including only water vapor from the humidity of room air from a room temperature to a high temperature with a relatively simple configuration.

  Even in an apparatus used at a high temperature such as a drying apparatus or a food processing apparatus, it is required to measure the humidity in the apparatus. However, conventional humidity sensors used at normal temperature are difficult to use at high temperatures. In particular, a structure in which a gauze (nonwoven fabric, what is called a wick) is spread on the wet bulb has problems such as weakness to heat, denaturation in hot water at 100 ° C., and scorching when dry.

  On the other hand, sensors capable of measuring at high temperatures have been developed (see Patent Documents 1 and 2). However, these sensors are expensive, or have problems such as sensor deterioration or damage due to condensation of water vapor. For this reason, the utilization to the apparatus which needs to measure with a wide water vapor | steam density | concentration, such as a drying apparatus and a food processing apparatus, or an apparatus which may produce a stain | pollution | contamination and a breakage is not progressing.

  In these apparatuses, quality control depends on empirical matters, and there are problems that the reproducibility of processing conditions is poor, control is insufficient and not optimized, and therefore energy efficiency is poor.

In research and development, a humidity measuring device that can easily measure absolute values is required. On the other hand, devices that are actually used for manufacturing, etc., can measure qualitative values or measure to the extent that processing conditions can be reproduced, and users can easily understand the structure and principle and are inexpensive. Desired. However, the current high-temperature humidity measuring apparatus has a problem that it does not meet such requirements.
JP 2001-201478 A JP 2008-82993 A

  That is, the present invention has been made in view of the above-described problems, and the object thereof is a simple configuration, which is less likely to cause deterioration of the sensor due to condensation and the like, and is capable of measuring qualitative values or reproducing processing conditions. It is an object of the present invention to provide a vapor measuring apparatus capable of measuring to the extent possible.

  As a result of diligent examination of the above problems, the present inventors have made a porous material that is temperature-stable and thermally stable as a moisture-sensitive part, and while appropriately supplying or discharging water from the outside to the moisture-sensitive part, By measuring the temperature of the moisture sensitive part while maintaining the state where water is present near the surface of the wet part or the water is evaporating, the room temperature is continuously increased even at a high temperature exceeding 300 ° C. A steam measuring device capable of measuring in a wide humidity range from superheated steam to superheated steam was obtained, and the present invention was completed. That is, the present invention is as follows.

  The steam measuring device of the present invention is a steam measuring device having a moisture sensitive part formed of a porous material and a first sensor for measuring a temperature in the vicinity of the surface of the moisture sensitive part. And a supply path for supplying water, and a discharge path for discharging water from the inside of the moisture sensitive part.

  In addition, the vapor measuring apparatus of the present invention includes a moisture-sensitive portion formed of a porous material, a first sensor that measures a temperature in the vicinity of the surface of the moisture-sensitive portion, and a moisture amount present on the surface of the moisture-sensitive portion. A steam measuring device having a second sensor for measuring, comprising: a supply path for supplying water into the moisture sensitive section; and a discharge path for discharging water from the moisture sensitive section. .

  The steam measuring device includes a control unit that controls water supply or water discharge based on the amount of water measured by the second sensor.

  The steam measuring device may include a third temperature sensor that measures the temperature of the gas around the moisture sensitive unit.

  The steam measuring device may include a pressure sensor that measures a pressure outside a moisture layer present on the surface of the moisture sensitive portion.

  The steam measurement device calculates a water vapor amount based on data from the first temperature sensor, the third temperature sensor, and the pressure sensor.

  The moisture-sensitive part is preferably formed of a ceramic porous material in which 0.1 μm to 10 μm pores and 10 to 30 μm pores are mixed.

  The moisture-sensing part may be provided with a flow path of water that penetrates a substantially central part of the moisture-sensing part. The moisture-sensitive part may have a columnar structure, and may be provided with a water flow path that passes through substantially the center in the axial direction of the column. The moisture sensitive part may have a spherical shape or a part of a spherical outer shape.

  The first sensor and the second sensor may be sensors having an electrode structure, and an electrical resistance change and / or a capacitance change may be detected through the electrodes.

  The steam measuring device of the present invention is a steam measuring device having a moisture sensitive part formed of a porous material and a first sensor for measuring a temperature in the vicinity of the surface of the moisture sensitive part. A supply path for supplying water

  The vapor measuring apparatus of the present invention may supply a liquid substance having a boiling point equal to or lower than the temperature of the surrounding gas to the moisture sensitive part, and measure the vapor concentration of the substance contained in the surrounding gas.

  This invention is an apparatus provided with said vapor | steam measuring apparatus.

  In the present invention, the above-described apparatus also functions as the humidifier or the humidification sensor.

  In the following description, the present invention will be described based on air, water, and water vapor. However, the present invention is not limited to air, water, and water vapor, and a liquid substance having a temperature below the ambient gas temperature in the moisture sensitive portion. The same can be applied to the case of supplying.

  The steam measuring apparatus of the present invention measures the temperature of the moisture sensitive part while maintaining the state where water is present near the surface of the moisture sensitive part or the water is evaporating. As a result, the humidity (the amount of water vapor in the gas expressed in terms of absolute humidity, water vapor concentration, water vapor partial pressure, etc.), even at high temperatures exceeding 300 ° C., continuously and over a wide humidity range from indoor air to superheated water vapor ) Can be measured.

  In particular, the steam measuring apparatus of the present invention can be used for a heating apparatus using superheated steam or a mixed gas of air and steam, rather than being used as an independent measuring instrument for accurately measuring an absolute value. For example, its value and usefulness are increased by incorporating it into various devices such as food processing devices, drying devices, sterilization devices, heating devices, and the like, in particular, where objects to be processed and gas are in direct contact with each other. As a result, as a control means for minimizing the amount of energy used by the apparatus, a control means for the most appropriate processing conditions according to the processing object and processing purpose, and a control means for making the processing conditions reproducible. Can be used.

FIG. 1 is a conceptual diagram illustrating the configuration of the vapor measuring apparatus according to the first embodiment. FIG. 2 is a conceptual diagram illustrating a configuration of a modified example of the steam measuring apparatus according to the first embodiment. FIG. 3 is a conceptual diagram illustrating the configuration of the vapor measuring apparatus according to the second embodiment. FIG. 4 is a conceptual diagram illustrating the configuration of the steam measuring apparatus according to the third embodiment. FIG. 5 is a conceptual diagram illustrating the configuration of the vapor measuring apparatus according to the fourth embodiment. FIG. 6 is a diagram for explaining the measurement principle of the steam measuring apparatus of the present invention. FIG. 7 is a graph showing the relationship between temperature and vapor mole fraction. FIG. 8 is a diagram for explaining the pore size distribution (mercury intrusion method) of the porous material used in the moisture sensitive part of the vapor measuring apparatus of the present invention. FIG. 9 is a graph obtained by measuring the responsiveness of humidity using the vapor measuring apparatus of the present invention. FIG. 10 is a graph for confirming whether or not water is present on the surface of the moisture sensitive part when the water vapor molar fraction is changed using the vapor measuring apparatus of the present invention.

DESCRIPTION OF SYMBOLS 1 Humidity sensing part 2 1st sensor 3 2nd sensor 4 3rd sensor 5 Pressure sensor 6 Calculation part 7 Control part 8 Supply path 9 Discharge path 10 Pump 11 Valve

The present invention is described in detail below.
(Embodiment 1)
FIG. 1 is a diagram showing an example of the configuration of the vapor measuring apparatus of the present invention. As shown in FIG. 1, the steam measuring device of the present invention includes a humidity sensing unit 1, a first sensor 2 for measuring the temperature near the surface of the moisture sensing unit, a supply path 8, and a discharge path 9. Is provided. Further, in the example of this figure, a calculation unit 6 is provided.

  As described in the measurement principle of the steam measuring device below, in order to measure the amount of water vapor, the temperature (Tsf) near the surface of the moisture sensitive part of the moisture sensitive part and the air temperature (Tgas) around the moisture sensitive part. And air pressure (PT). The vapor measuring apparatus according to the present embodiment is suitable for use when the temperature around the moisture sensitive portion (Tgas) and the pressure (PT) in the airflow portion are known by some means.

(Moisture sensitive part)
In the present invention, the moisture-sensing part 1 is a part for measuring the temperature of water in contact with the surrounding airflow by causing water to exist on the surface thereof. The moisture sensitive part 1 is formed of a thermally stable porous material. The porous material is preferably ceramic. This is because ceramic is thermally stable. The porous material preferably has a high wettability in order to allow water to exist on the surface. In the present specification, “wetability” means ease of compatibility between the surface of the porous material and water (free water).

  In the porous material, the void structure is such that the water present in the void is not easily affected by gravity, and fine pores (0.1 to 10 μm) for the water to wet the entire surface of the moisture sensitive portion by capillary suction force. ) And supplying water to the surface of the moisture sensitive part with a small pressure that can be generated by a space between the water supply and the vicinity of the surface of the moisture sensitive part or the head, or excess water on the surface. It is good to have pores (10 to 30 μm) for sucking and discharging. It is more preferable that the fine pores have a structure having almost no pores of 30 μm or more because water existing in the voids is hardly affected by gravity. These pore structures may be uniform, or may be non-uniform such that they vary from site to site depending on the use environment and the shape of the moisture sensitive part. Note that the pores are not completely circular. Therefore, in the present invention, the size of the diameter is calculated by mechanically calculating a diameter in a certain direction on a plane as a diameter. The method for calculating the diameter is not particularly limited, and is a known method. For example, the pore diameter measured by a mercury intrusion method or the like.

Specifically, it is preferable that the diameter equivalent diameter satisfies the following conditions.
(1) For easy movement to the surface by capillary suction force, it is desirable that the pore size distribution is wide in the unitary pore structure (10 to 30 μm).
In addition, it can be expected that the moisture transfer coefficient is larger in the binary pore structure than in the one-pore structure.
(2) In order for water to move appropriately due to a pressure difference, it is desirable that there are 10 to 30 μm pores.
(3) In order to make it less susceptible to the influence of gravity, it is desirable not to have a pore diameter larger than 30 μm.
(4) The porosity is limited from the viewpoints of ease of manufacturing, manufacturing cost, and material strength, but it is preferably 0.45 or more and higher. The porosity is measured by a known method such as a mercury intrusion method or a method of including water.

  The shape of the moisture sensitive portion 1 is not particularly limited. For example, the shape is spherical, columnar (columnar, prismatic, etc.), pyramid (conical, pyramidal, etc.), frustum (frustum, pyramidal). , Etc.), bell shape, spindle shape, plate shape (flat plate shape, curved plate shape, corrugated plate shape, cubic shape, etc.). In the present specification, “the outer shape of a part of a sphere” means one having an outer shape including a part of a sphere, such as a hemisphere, a frustum shape, or a bell shape. In addition, the moisture sensing section is connected to the supply path and the discharge path, and the flow through the moisture sensing section is used to circulate water inside the moisture sensing section and hold water to be supplied to the surface. A road (space) is provided. For example, in the case where evaporation occurs uniformly from the entire surface around the moisture-sensitive part 1, if the shortest distance from the flow path to the surface of the moisture-sensitive part is substantially the same length, water is evenly supplied to the surface of the moisture-sensitive part. This is preferable. If the evaporation speed and the water movement speed from the flow path to the surface differ depending on the part of the surface of the moisture sensitive part due to the influence of the environment to be measured, depending on the evaporation speed distribution of the surface part or the external pressure distribution (dynamic pressure) It is preferable that the moisture-sensitive part has an outer shape, a channel shape, and a porous structure so that water can be supplied from the channel to the surface. A preferable outer shape of the moisture-sensitive portion has a cylindrical shape, a spherical shape, or a part of a spherical shape for reasons such as ease of manufacture.

  The flow path of the moisture sensitive portion 1 is not particularly limited as long as it connects the supply path 8 and the discharge path 9, and is a single tube, U-shaped tube, double tube that penetrates the porous material, or these A combination of a plurality of these may be used. In the case of a single tube or a U-shaped tube, both ends thereof, and in the case of a double tube, the inner tube and the outer tube may be connected to either the water supply channel or the water discharge channel, respectively. In the case of a sphere, it is a spherical space near or near the center of the sphere, and as an example of a small moisture-sensitive part shape that is relatively easy to manufacture. I just need it.

  There is no restriction | limiting in particular in the magnitude | size of the moisture sensitivity part 1, According to the objective to be used, it can select suitably. Moreover, there is no restriction | limiting in particular in the internal diameter of a flow path, the position in a moisture-sensitive part, and a magnitude | size, According to the intended purpose, environment, the pore structure of a porous material, etc., it can select suitably. For example, in the case where the moisture sensitive part is a columnar shape having a diameter of about 10 mm, it may be a tube having a diameter of 0.5 to 7 mm.

  The portion of the surface of the moisture sensitive portion 1 where heat is applied in contact with the surrounding airflow is in a state where water is present. As described below, the temperature of this part is important. On the other hand, it is preferable that the portion where heat is not directly transmitted from the airflow has a structure in which water is not supplied from the flow path so that evaporation does not occur, or the surface portion where water does not easily evaporate is insulated. It is preferable. For example, the moisture-sensitive part is a part that is fixed to the supply path or the discharge path with a sealant or the like, or a part that contacts the apparatus wall surface for attachment.

  The moisture sensitive part 1 formed of a porous material having such a void structure is not particularly limited and can be produced by a known method. For example, a material for a moisture-sensitive part having an appropriate pore structure can be obtained by mixing an inorganic solid material with a powdery substance containing carbon as a main component and baking at a high temperature.

  In addition, it is desirable that the moisture sensitive portion 1 has a shape that can be easily replaced.

(First sensor)
The first sensor 2 is provided in the vicinity of the surface of the moisture sensitive unit 1. The portion where heat is applied by contact with the surrounding airflow on the surface of the moisture sensitive portion 1 is in a state where water is present. The first sensor 2 is provided at this portion. The first sensor 2 measures the temperature near the surface of the moisture sensitive unit 1. The first sensor 2 measures temperature based on, for example, a thermocouple, a resistance temperature detector, or a similar principle. In addition, the vicinity of the surface of the moisture sensitive portion 1 includes the inside of the moisture sensitive portion. In this case, the first sensor is inserted into the moisture sensitive part.

(Supply / Discharge)
The supply path 8 and the discharge path 9 are pipes which are formed or protected by a material having heat resistance, preferably heat insulation. The supply path 8 and the discharge path 9 both have one end connected to the moisture sensing section 1 and the other end connected to a water supply section provided outside the airflow space (for example, a pipe or a processing chamber) for measuring water vapor. Connected to the water drain. The water supply unit and the water discharge unit may be different or the same. In the example of FIG. 1, the water supply unit and the water discharge unit are the same.

  The supply path 8 and the discharge path 9 are formed of a material having heat resistance, preferably a material having heat insulation, at a portion connected to the moisture sensitive portion 1 or a portion exposed to an air flow space for measuring water vapor. Or a protected tube. Specific examples of these materials include silicon, Teflon (registered trademark), and stainless steel. Also in the water supply part, it is good to be formed with these materials.

  The other end of the supply passage 8 and the discharge passage 9 that is connected to the moisture sensing portion 1 outside the airflow space for measuring water vapor in order to make the pressure in the flow passage of the moisture sensing portion 1 appropriate. In addition, the thickness and length of the pipe and the positional relationship with the water tank may be determined. Moreover, when water cooling is required in order to make water temperature suitable, it can also be used as a water cooling part.

  The supply path 8 and the discharge path 9 are heated by water in a portion exposed to the airflow space or radiated including a water tank in a portion not exposed to the airflow in order to make the temperature of the water supplied to the moisture sensitive unit 1 appropriate. It is desirable to adjust the presence or absence of heat insulation in consideration of the effect of cooling.

  The supply path 8 and the discharge path 9 are each provided with pressure control means in the flow path such as the pump 10 and the valve 11, or are configured to cause a head difference between the water supply section and the water discharge section. As a result, the amount of water supplied and the amount of water discharged from the moisture sensitive portion 1 (pressure in the flow path space in the moisture sensitive portion) are adjusted automatically or manually so that the surface has an appropriate amount of moisture.

  When water is supplied with a head difference without using a pump for water supply, adjustment is made according to the head difference or the length and thickness of the pipes of the water supply channel 8 and the drainage channel 9 and the water level of the drainage tank. Furthermore, it is also possible to adjust the amount of discharged water (actually, the water pressure of the pipe line in the moisture sensitive part 1) by providing a control part in the pipe part. In this case, a pump is required to feed the water in the drainage tank to the water supply tank, but since the need for control is low, an inexpensive one can be used.

  The amount of water supply / drainage is preferably determined or controlled appropriately from the viewpoints of the amount of water evaporation in the moisture-sensitive part, the improvement of response time when the humidity of the airflow is reduced, and the control of the water temperature supplied to the moisture-sensitive part. . In the water temperature control, for example, if the pipe line of the supply unit exposed to high temperature is long, water may be heated and boil between them. In this case, insulate the pipes in the high-temperature part, and do not insulate the pipes and water tanks outside the air flow space to be measured for cooling. It is preferable to increase the amount of water supply / drainage.

  It is desirable that the temperature of water in the portion supplied to the moisture sensitive portion is near the wet bulb temperature in order to improve measurement accuracy. For this reason, it is advisable to optimize the heat dissipation and heat insulation design in the piping. A mechanism for positive control may be provided as necessary.

  The adjustment of the amount of water may be performed manually, for example, or may be performed by image analysis of the surface of the moisture sensitive portion 1 to observe the wet state of the surface of the moisture sensitive portion 1.

(Calculation unit)
The calculating part 6 calculates | requires water vapor | steam amount from the temperature of the surface vicinity of the measured moisture sensitive part 1. FIG. In this embodiment, since only one sensor is required, a simple structure can be obtained. It is preferable to apply when the evaporation rate is slow under the measurement conditions and the supply of water is sufficient mainly by the movement of water with only capillary suction force.

(Other configurations)
Moreover, it is good also as a structure which provides the mechanism for measuring electrical conductivity in the water supply part, and the mechanism for controlling electrical conductivity as needed. Moreover, it is good also as a structure which provides the mechanism for wash | cleaning the stain | pollution | contamination by components contained in water, such as a scale of a moisture sensitive part.

  As a mechanism for preventing contamination due to the scale and the like of the moisture sensitive part, water is always purified using an ion exchange membrane, ion exchange resin, reverse osmosis membrane (hereinafter referred to as “RO membrane”), etc. The method etc. are mentioned. It is possible to provide a mechanism for outputting a maintenance timing signal according to the water state and the sensor signal. Or self-cleaning function (function to circulate and wash with citric acid etc. while measurement is stopped, periodically sucking and discharging moisture from the sensor unit, or dropping water on the sensor surface by supplying excessive water) You may make it the structure which has.

  The device for purifying water can be installed in a pump inlet, outlet, water supply tank, drainage tank, or a pipe connecting the water supply tank and the drainage tank. It is desirable that these are cartridge type and can be easily replaced. By providing the function of measuring electrical conductivity for measuring the ion concentration, more advanced control and water management are possible.

(Modification of Embodiment 1)
The example of Embodiment 1 shown in FIG. 1 can be further simplified. As shown in FIG. 2, the pump and the discharge path are omitted from the configuration of FIG. Other configurations are the same as those in FIG.

  In the case of the configuration shown in FIG. 2, a small water supply means such as a cartridge is used, or the pore structure of the moisture sensitive portion and the thickness of the pipe line are maintained so that the surface of the moisture sensitive portion can be kept wet. Adjust the sheath and length. This embodiment is particularly suitable for short-time use.

(Embodiment 2)
FIG. 3 is a diagram showing an example of the configuration of the vapor measuring apparatus of the present invention. As shown in FIG. 3, the steam measuring device of the present invention exists near the surface of the moisture sensitive part 1, the first sensor 2 for measuring the temperature near the surface of the moisture sensitive part, and the moisture sensitive part. A second sensor 3 for measuring the moisture content, a supply path 8 and a discharge path 9 are provided. Moreover, in the example of this figure, the calculating part 6 and the control part 7 are provided.
Except for the second sensor 2 and the control unit 7, the configuration is the same as in FIG.

(Second sensor)
The second sensor 3 is provided in the vicinity of the surface of the moisture sensitive unit 1. The portion where heat is applied by contact with the surrounding airflow on the surface of the moisture sensitive portion 1 is in a state where water is present. The second sensor 3 is provided at this portion. The second sensor 3 measures the amount of moisture present near the surface of the moisture sensitive part. In this specification, the amount of moisture means the degree of whether or not the surface of the moisture sensitive part is wet. A specific example of the second sensor 3 includes a sensor that measures changes in electrical conductivity, dielectric constant, capacitance, and the like depending on the amount of moisture. Those physical quantities may be measured (contact measurement) as the output from the electrode in contact with the surface of the moisture-sensitive part, or via an optical fiber or optical element arranged in a non-contact manner near the surface of the moisture-sensitive part. Alternatively, measurement (non-contact measurement) may be performed as a change in infrared absorption.

  When the water content is measured by electric conductivity in the vapor measuring apparatus of the present invention, it is preferable to use water having an appropriate electric conductivity. For this reason, it is desirable to attach an ion exchange resin, an ion exchange membrane, an RO membrane, or a water purifier for appropriately removing salts, ions, scales, dirt, etc. dissolved in water to the water supply unit.

(Control part)
When the second sensor 3 is used as shown in FIG. 3, a signal for controlling the supply or discharge of water is transmitted from the control unit 7 using data obtained by measuring the amount of water near the surface of the moisture sensitive unit 1. Specifically, the increase / decrease in the supply of water from the pump and the increase / decrease in the discharge of water from the humidity sensing unit are performed.

  When both the first sensor 2 and the second sensor 3 are sensors having an electrode structure, the first sensor 2 and the second sensor 3 are used to wet the surface of the moisture sensitive portion 1. Can be detected. For example, thermocouples can be used for the first sensor 2 and the second sensor 3. In this case, the second sensor can be used as a backup when the first sensor fails or to improve the temperature measurement accuracy.

  In the case of using a sensor having an electrode structure, in FIG. 3, both the first sensor 2 and the second sensor 3 are used as electrodes either continuously or intermittently. For example, when measuring the amount of water using electrical conductivity, the controller 7 does not increase the supply of water if it detects the energization of the first sensor 2 and the second sensor 3. On the other hand, if the surface of the moisture sensitive portion 1 is dry, no current is supplied. If energization is not detected, the control unit 7 increases the pressure of the pipe line to increase the supply of water, or closes the valve 11 to supply water to the surface of the moisture sensitive unit 1.

(Embodiment 3)
FIG. 4 is a diagram showing an example of the configuration of the steam measuring device of the present invention. As shown in FIG. 4, the vapor measuring apparatus of the present invention includes a moisture sensing unit 1, a first sensor 2 for measuring the temperature near the surface of the moisture sensing unit, and the gas surrounding the moisture sensing unit 1. A third sensor 4 for measuring temperature, a supply path 8 and a discharge path 9 are provided. Moreover, in the example of this figure, the calculating part 6 and the control part 7 are provided.
Except for the third sensor 4, the configuration is the same as in FIG. In addition, in the example of this figure, although it has the 2nd sensor 3 and the control part 7 which measure the moisture content which exists in the surface vicinity of the moisture sensitive part 1, the 2nd sensor 3 and the control part 7 are included. Can be omitted. In addition, the modified example of the above embodiment may include a third sensor as in the present embodiment.

  The vapor measuring apparatus of the present embodiment is suitable for use when the pressure of the airflow portion is known.

(Third sensor)
As shown in FIG. 4, the third sensor 4 measures the ambient temperature (Tgas) around the moisture sensitive unit 1. The third sensor 4 only needs to be able to measure the temperature of the airflow that is not affected by the moisture sensitive unit 1. The third sensor 4 may be fixed to the moisture sensitive unit 1 or separated. The third sensor 4 can measure the temperature of the gas, such as a thermocouple or a resistance temperature detector.

(Embodiment 4)
FIG. 5 is a diagram showing an example of the configuration of the steam measuring device of the present invention. As shown in FIG. 5, the steam measuring device of the present invention includes a humidity sensing unit 1, a first sensor 2 for measuring the temperature near the surface of the moisture sensing unit, and the temperature of the gas around the moisture sensing unit. A third sensor 4 for measuring the pressure, a pressure sensor 5, a supply path 8, and a discharge path 9. Moreover, in the example of this figure, the calculating part 6 and the control part 7 are provided.
Except for the third sensor 4 and the pressure sensor 5, the configuration is the same as in FIG. In addition, in the example of this figure, although it has the 2nd sensor 3 and the control part 7 which measure the moisture content which exists in the surface vicinity of the moisture sensitive part 1, the 2nd sensor 3 and the control part 7 are abbreviate | omitted. You can also The third sensor 4 can also be omitted.

  The steam measuring apparatus according to the present embodiment is suitable for use when the amount of water vapor is determined using the wet bulb temperature (Tsf), the ambient temperature (Tgas) around the moisture sensitive portion, and the pressure (PT) of the airflow portion. .

(Pressure sensor)
As shown in FIG. 5, the pressure sensor 5 is provided to measure the pressure (total pressure PT) outside (airflow) of the moisture layer present on the surface of the moisture-sensitive part 1. The pressure sensor 5 may be fixed to the moisture sensitive part 1 or separated. The type of the pressure sensor 5 is not particularly limited as long as it can withstand the use environment, and a known pressure gauge can be used. Moreover, the water pressure of a supply channel or a drainage channel is measured, and the value estimated based on the value can also be used. As a pressure gauge that can be used in the present invention, when the change in pressure over time is small, for example, a pressure gauge for visual observation using a Bourdon tube or a simple method such as a U-tube manometer is used. There may be. Furthermore, when the pressure is close to the atmospheric pressure and accurate measurement is difficult due to the high temperature, the calculation unit 6 can obtain the calculation result by using the value of the atmospheric pressure approximately.

[Measurement principle]
Below, the measurement principle of the vapor | steam measuring apparatus of this invention is demonstrated based on FIG. Water placed in the gas has its temperature between the gas and the water surface due to convective heat transfer from the gas in contact with the water surface (including conduction heat transfer from the gas if there is no gas flow). Based on the difference, heat transfer (qcv) occurs. Further, heat transfer (qr) occurs on the surface of the water due to radiation (thermal radiation) heat transfer from the surroundings.

  If there is a temperature difference between the surface of the water (liquid phase side of the gas-liquid interface) and the inside of the water, the heat transfer is carried out from the surface of the water to the interior of the water (including the movement of heat accompanying the movement of water). Movement (qcd) occurs.

  The water surface (the gas phase side of the gas-liquid interface) has a water vapor partial pressure (concentration) equivalent to the saturated vapor pressure at the water temperature, which is due to the difference in water vapor partial pressure or the total pressure with the surrounding gas. A water vapor flow (j) occurs from the surface of the water to the surrounding gas.

On the surface of water, the relationship qcv + qr = qcd + jγ is established. In this equation, j is the evaporation rate of water (condensation rate if negative), and γ is the latent heat of evaporation of water. The surface of the water has a temperature at which this relationship is established. From this, it is possible to theoretically know the humidity (water vapor partial pressure, water vapor concentration, etc.) of the surrounding gas from the surface temperature of water. These principles are described, for example, in Transport Phenomena 2 ^nd Ed. , P684, R.M. B. Bird, W.M. E. Stewart, E .; N. Lightfoot, John Wiley AND Sons, Inc. (2002), USA, etc.

  As a measurement method of absolute humidity or relative humidity using these measurement principles, when qr and qcd are both 0 and the pressure is near atmospheric pressure, a method of measuring from the dry bulb temperature and the wet bulb temperature (JIS Z8806) is available. Widely known. However, these assume the measurement of humidity at temperatures below 100 ° C.

  Relative contribution of radiation heat transfer qr to qcv in a steady airflow with sufficient wind speed to accurately measure humidity (water vapor partial pressure and absolute humidity) under relatively low humidity conditions It is necessary to measure the temperature of water when convection heat transfer is small and all convective heat transfer is used as latent heat of vaporization of water.

  In addition, under high-temperature and high-humidity conditions close to superheated steam, the saturation vapor pressure dependence on temperature is stronger than in low-temperature and low-humidity conditions. In addition, in the calculation, the influence of PT on the calculation result increases. Therefore, in order to accurately measure the humidity under a high humidity condition close to superheated steam, a slight temperature measurement error or a change in pressure can be a large measurement error in estimating the water vapor partial pressure. It is desirable to measure an accurate pressure, and if a temperature or pressure measurement error is known, an error range may be calculated or an error due to these may be corrected. On the other hand, the error due to the effect of radiation heat transfer qr is small compared to the case of low humidity.

  Furthermore, when the temperature of the gas is high and the evaporation rate is high, or under conditions where radiation heat transfer affects, it is preferable to correct those effects according to the required measurement accuracy. The influence of radiation can be reduced by attaching a radiation shielding plate. When a moisture sensitive part is installed in the pipe, the flow velocity can be adjusted by providing a bypass part in the pipe to be measured. In addition, when the airflow conditions (flow velocity, temperature, humidity, etc.) change with time, qcd changes with time as the surface temperature of water changes, so theoretical calculations or measured values such as temperature (water supply temperature, Correction may be made based on the value of qcd estimated from the drainage temperature, sensor internal temperature, and the like.

  When the flow velocity of the surrounding fluid is low, the contribution of radiation heat transfer increases relatively, and the influence of natural convection increases. Therefore, the calculation error based on the similarity law of heat and mass transfer (Chilton-Colburn law) Will also increase. These may also be corrected based on calibration in order to improve the measurement accuracy.

  As described above, by using the measuring apparatus of the present invention, even in a high temperature range exceeding 300 ° C., water can be supplied and temperature can be measured in principle. Moreover, the measuring apparatus of the present invention is not affected by oxidation, deterioration due to moisture condensation under high humidity conditions, and the like. That is, the measuring apparatus of the present invention can improve the performance of an apparatus that uses high-temperature and high-humidity air or superheated steam.

In the steam measuring device of the present invention, the amount of water vapor is measured by, for example, using the value of Tsf for Tad and incorporating the following formulas (1) and (2) into the computing unit.

感湿部の表面付近の温度Ｔｓｆ、感湿部の周囲の気体の温度Ｔｇａｓ、圧力センサから得られる圧力（ＰＴ）、および、感湿部の表面付近の温度から（２）式により求められる水蒸気分圧（Ｐｓ,ｓａｔ）から、式（１）により水蒸気量を求めることができる。なお、Ｔｇａｓ、圧力センサから得られる圧力が既知の場合（実施の形態１）、圧力センサから得られる圧力が既知の場合（実施の形態２）、Ｔｓｆ、Ｔｇａｓ、圧力センサから得られる圧力全てを測定する場合（実施の形態４）のいずれの場合でも、式（１）から水蒸気量を求めることができることがわかる。

Water vapor determined by the equation (2) from the temperature Tsf near the surface of the moisture sensitive part, the temperature Tgas of the gas around the moisture sensitive part, the pressure (PT) obtained from the pressure sensor, and the temperature near the surface of the moisture sensitive part From the partial pressure (Ps, sat), the amount of water vapor can be determined by equation (1). When Tgas and the pressure obtained from the pressure sensor are known (Embodiment 1), when the pressure obtained from the pressure sensor is known (Embodiment 2), Tsf, Tgas and all the pressures obtained from the pressure sensor are all It can be seen that in any case of measurement (Embodiment 4), the amount of water vapor can be determined from Equation (1).

  Even if not based on the above method, the water vapor obtained from the temperature Tsf near the surface of the moisture sensitive portion, the temperature Tgas of the gas around the moisture sensitive portion, the pressure obtained from the pressure sensor, and the temperature near the surface of the moisture sensitive portion. Other methods may be used as long as the amount of water vapor can be measured from the partial pressure.

  Depending on the state of implementation, it may be affected by radiation. To eliminate the effects of radiation, install a radiation shielding device around the sensor, bleed (suction), and attach this sensor to a pipe section of low radiation material, or use a material with low emissivity for moisture sensitivity. There are methods such as manufacturing parts.

  Temperature measurement error may occur. In this case, the temperature measurement error can be reduced by using a minute platinum resistance thermometer or the like instead of the thermocouple, or using a sheath thermocouple. In the case of a sheathed thermocouple, the structure can be simplified by inserting from the axial end surface of the moisture sensitive portion 1.

When the first sensor is attached to the surface, the response time is accelerated. For this reason, the attachment position is preferably the surface. On the other hand, since the surface is affected by the airflow temperature, it is significant from a practical aspect if it is attached slightly inside the surface.

  When mounted on the surface, or when mounted on the inner side of the surface, in each case, a temperature sensor is attached to one or more other locations in the inner radial direction of the moisture sensitive portion 1, for example, a portion slightly close to the surface from the water flow path, or the water temperature (supply) Measure water temperature, drainage temperature, or both) and calculate qcd or humidity (water vapor concentration) using these data, so that faster response time and higher accuracy can be measured. It becomes possible. In this case, the water vapor concentration is obtained by correcting the equation (1) or using another heat conduction equation or a heat / mass transfer model.

[Control method of water vapor amount (humidity)]
If the water vapor concentration is higher than the specified value, increase the amount of air supplied by the blower to the installed device (food processing, sterilization, heat treatment, etc.). Operating the valve or damper on the side connected to the outside to open the air (air), or reducing the amount of steam supplied from the boiler and the amount of humidification in the hot air path (apparatus: like a wet scrubber) In addition, it is preferable to perform control such as spraying (reducing the supply amount of water, lowering the supply water temperature, etc.) using a wet porous material portion similar to the moisture sensitive portion of the present invention.

  On the other hand, when the water vapor concentration (or Tsf) is lower than the predetermined value, the air supply amount from the blower or the like is reduced, the intake damper is controlled in the closing direction, the water vapor supply amount from the boiler (in the case of an electric boiler, input) (Such as increasing the amount of spray, simultaneously increasing the supply water temperature, or increasing the hot air temperature at the supply location, etc.) Good.

  If Tsf exceeds the boiling point temperature in PT (100 ° C at atmospheric pressure), the measured value is judged to be abnormal, a warning is issued, and the concentration output is changed to a safe value. It is desirable to control the amount of water vapor (humidity) by increasing the amount. Such a state can occur when the water supply is not operating properly, or when the airflow temperature is abnormally high, or when the flow rate is fast and “the evaporation rate is unexpectedly high”.

  A vapor measuring device in which only the first and third sensors are attached can also be used in the device. This is a case where PT can be approximated to atmospheric pressure, and water can be supplied so that the surface of the moisture sensitive portion can be sufficiently wetted only by capillary suction. The calculation unit, for example, designs an electronic circuit and a calculation program so that a predetermined voltage signal output value is obtained for the water vapor concentration after AD conversion and calculation of the first and third temperature signals converted into voltage The output signal is displayed on a voltmeter and simultaneously output to a humidity control circuit or an external device. A small microcomputer, a microprocessor, a microcontroller, or the like can be used for the arithmetic processing and control.

[Usage example of the steam measuring apparatus of the present invention]
By incorporating the measuring device of the present invention into various devices that use superheated steam, a mixed gas of air and water vapor, or experimental devices for research and development, it is possible to grasp processing conditions such as humidity, increase the efficiency of the device, or It is possible to grasp or control to the optimum processing conditions according to the processing object and processing purpose. In the above description, the steam is used. However, the steam measuring apparatus is not limited to the steam, and can be similarly applied to a liquid substance having a boiling point equal to or lower than the temperature of the surrounding gas.

  As a practical form, for example, it is possible to manage humidity (water vapor concentration) by applying it to an air circulation type continuous treatment device such as (heat treatment device for seeds) of JP 2008-17828 A. .

  By attaching it to the inside of the steam convection oven or the exhaust section of a commercial convection oven, it is possible to increase the efficiency and control the humidity inside the cabinet by suppressing the supply of excess water vapor.

  It can be used for grasping and controlling the heat treatment conditions in an oven or an experimental apparatus using superheated steam, saturated steam, steam or other mixed gas.

  In a spray dryer, a flash dryer, a heat treatment device, or the like, the enthalpy measurement and operating conditions of the exhaust gas can be grasped by attaching a sensor to the exhaust from the drying chamber or the exhaust part from the device to the outside air. Furthermore, quality control and energy saving can be performed by controlling the humidity of these devices.

[Application example of the steam measuring apparatus of the present invention]
The vapor measuring apparatus of the present invention can be further applied as follows.
By measuring the evaporation amount (evaporation rate) of water per unit time from the difference between the supply amount and the discharge amount of water to the moisture sensitive part, the heat transfer amount and heat transfer coefficient by convection and radiation can be obtained. If the relationship between the flow velocity and the heat transfer coefficient is known, the flow velocity can be measured.

  Specifically, using a pump, the drainage tank and the water supply tank are the same, and the amount of evaporation is measured by measuring the amount of water in the tank in detail with an electronic balance or the like. Since the value is proportional to the amount of heat transfer, a convection (or a combination of convection and radiation) heat transfer coefficient between the airflow and the moisture sensitive part can be obtained. In addition, the flow velocity of the airflow can be obtained from the value. Furthermore, a liquid other than water can be flowed in the same manner as described above in a predetermined condition and in an air current of components, and the same measurement can be performed. As a result, using this measurement device, the approximate values of the heat transfer coefficient, mass transfer coefficient, and other factors such as the thermal conductivity, kinematic viscosity, and fluid-liquid substance diffusion coefficient of fluids can be simplified. Can be sought.

  By appropriately selecting the pore structure of the moisture-sensitive part suitable for the pressure to be used and the water supply and discharge method, in addition to the use at atmospheric pressure, the absolute pressure that contributes greatly to convective heat transfer is up to about 20 kPa. Even under a reduced pressure or a pressure higher than atmospheric pressure, although the error of the absolute value increases, the mixing ratio of water vapor and air can be measured or the qualitative change tendency of the mixing ratio can be monitored.

  By supplying a gas other than air or an appropriate liquid to the moisture sensitive part, it can be applied to the measurement of the component concentration in the airflow other than the air-water system.

  For example, even if it is an organic solvent including alcohol such as methanol and ethanol, antifreeze, etc., if the boiling point is a liquid substance having a temperature equal to or lower than the temperature of the surrounding gas, by obtaining an appropriate arithmetic expression, The substance concentration can be measured with this measuring apparatus. In addition, even when liquid substances containing two or more components are included, if the concentration of two or more components on the surface of the moisture-sensitive part can be measured with an electrical resistance or other sensor, a calibration equation is obtained for each concentration to obtain two or more components. The concentration of the components can be measured simultaneously. That is, the vapor measuring apparatus of the present invention can measure not only the substance concentration in the airflow at a high temperature but also the substance concentration in the airflow in a state of 0 ° C. or lower such as a freezer.

  A part of the surface of the moisture sensitive part is processed with glaze or a high temperature sealant so that moisture cannot move, and a heat insulating material is attached to adjust the area of heat transfer and evaporation surface. Thereby, the measurement accuracy of the steam measuring device of the present invention or the accuracy when measuring the heat transfer coefficient can be improved. For example, when the moisture sensitive portion is cylindrical, errors due to the influence of the end face can be reduced by processing the end face.

  When this steam measuring device is incorporated in a device for measuring water vapor, it can function as a humidification sensor or a humidifier in addition to the function of the steam measuring device. Specifically, when the steam measuring device detects that the device is below a predetermined humidity, it sends a signal instructing an increase in humidity to the control unit of the device to humidify the inside of the device, or the device is For example, when the steam measuring device detects that the humidity has become lower than the humidity, the steam measuring device supplies a large amount of water to the moisture sensitive portion, and the steam measuring device itself supplies the humidity.

Example 1

A commercially available air flow meter for normal temperature and a predetermined amount of water vapor measured by the condensation method were mixed to produce a gas having a predetermined water vapor molar fraction. Considering an ideal gas, it is equivalent to water vapor partial pressure / total pressure. The steam measuring apparatus shown in FIG. 5 (length in the major axis direction: about 5 cm, outer diameter: about 9 mm) is prepared, and the temperature measured by the moisture sensitive part 1 is used as the adiabatic cooling temperature, assuming that the Lewis relationship is established. The partial pressure was determined. The calculation is described in, for example, literature (Ikeda et al., JSME 2009 Annual Conference Proceedings, Vol. 3, No. 09-1, pp. 101-102 (2009)), in particular. The simplest method without correction is used. The results are shown in Table 1. In Table 1, the calibration condition means a predetermined water vapor mole fraction of the produced gas, and the airflow temperature means an actual measurement value in the apparatus at each airflow temperature. FIG. 8 shows the pore size distribution (mercury intrusion method) of the porous material used in the moisture sensitive part 1 of the manufactured device. The porosity of the moisture sensitive part used in this example was about 0.5.

  From Table 1, it can be seen that the water vapor partial pressure is estimated (assuming qcd and qr are 0), and the measurement can be performed with an accuracy of about 5% maximum error.

(Example 2)
Using the apparatus shown in FIG. 4, the response time was confirmed by changing the humidity in steps, using an apparatus (not shown) for switching between the produced air and water vapor. The experiment was performed under the conditions that the air flow flux was 1 m / s and the wet bulb temperature was changed from 80 ° C to 100 ° C. The results are shown in FIG. From FIG. 9, it can be seen that the water vapor mole fraction (humidity) can be measured stably over 1 hour with high responsiveness over a wide range from 0 to 1. In addition, what is represented by the straight line in a graph shows the approximate value of a flowmeter, and what is represented by the curve means the measured value at the time of using this vapor | steam measuring apparatus.

(Example 3)
FIG. 10 shows the result of recording the signals of the first to third sensors when the airflow temperature Tgas is about 200 ° C. and the flow velocity U is about 1 m / s. From FIG. 10, the airflow humidity is changed from 0.4 (high humidity air) to 1 (superheated steam) from 20 seconds to 40 seconds after the start of recording. It can be seen that the temperature of the first sensor changes when the water vapor mole fraction is changed. Moreover, it turns out that it is 100 degreeC on the conditions of the water vapor | steam molar fraction 1. The signal E (right axis scale of the graph) from the second sensor 3 (electric resistance sensor having an electrode) shows an increasing tendency when the amount of water increases, and indicates 0 V when water is exhausted. From FIG. 10, after the water vapor mole fraction increased, E rose to 4.7V and then dropped to 3.8V. From this, the amount of water in the vicinity of the second sensor 3 increases after the water vapor mole fraction becomes 1, and then decreases, but the state where water is present on the surface of the moisture sensitive portion is maintained. Recognize. From the third sensor, the air temperature during measurement was about 195 ° C.

Claims (15)

A moisture sensitive portion formed of a porous material;
A vapor measuring device having a first sensor for measuring the temperature near the surface of the moisture sensitive part,
A supply path for supplying water into the moisture sensitive part;
A steam measuring device comprising: a discharge path for discharging water from the inside of the moisture sensitive unit. A moisture sensitive portion formed of a porous material;
A first sensor that measures the temperature near the surface of the moisture sensitive portion; a second sensor that measures the amount of moisture present on the surface of the moisture sensitive portion;
A steam measuring device comprising:
A supply path for supplying water into the moisture sensitive part;
A steam measuring device comprising: a discharge path for discharging water from the inside of the moisture sensitive unit.   The steam measurement device according to claim 2, further comprising a control unit that controls supply or discharge of water based on the amount of moisture measured by the second sensor.   The steam measurement device according to claim 1, wherein the steam measurement device includes a third temperature sensor that measures a temperature of a gas around the humidity sensing unit.   The steam measurement device according to claim 1, wherein the steam measurement device includes a pressure sensor that measures a pressure outside a moisture layer existing on a surface of the moisture sensitive unit.   The steam measurement device according to claim 1, wherein the steam measurement device calculates a water vapor amount based on data from the first sensor, the third sensor, and the pressure sensor.   The said moisture sensitive part is a vapor | steam measuring apparatus of Claim 1 or 2 currently formed with the ceramic porous material in which the 0.1 micrometer-10 micrometers pore and the 10-30 micrometers pore were mixed.   The steam measuring device according to claim 1, wherein the moisture sensing unit is provided with a flow path of water penetrating a substantially central portion of the moisture sensing unit.   The steam measurement device according to claim 1, wherein the moisture sensitive portion has a cylindrical structure, and is provided with a water flow path penetrating through a substantially central portion of the column.   The steam measurement device according to claim 1, wherein the moisture sensing unit has a spherical shape or an outer shape of a part of a spherical shape.   The steam measuring device according to claim 2, wherein the first sensor and the second sensor are sensors having an electrode structure, and a change in electric resistance and / or a change in capacitance is detected via the electrode. A moisture sensitive portion formed of a porous material;
A vapor measuring device having a first sensor for measuring the temperature near the surface of the moisture sensitive part,
A supply path for supplying water into the moisture sensitive part,
A steam measuring device comprising:   3. The vapor measuring apparatus according to 1 or 2, wherein a liquid substance having a boiling point equal to or lower than a temperature of surrounding gas is supplied to the moisture-sensitive part, and the vapor concentration of the substance contained in the surrounding gas is measured.   The apparatus provided with the vapor | steam measuring apparatus in any one of the said Claims 1-13. The apparatus according to claim 14, wherein the vapor measuring device also functions as a humidifier or a humidification sensor.

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