JPH09166496A - Method for inspecting pipe deposit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To understand the condition of deposits in a pipe by measuring the temperature change in the surface of the pipe. SOLUTION: A liquid film retaining member 18 is fixed to a pipe 16 and a nozzle 36 is provided at a position opposite to tight adhesion surface 23. Then, a temperature measurement part 14 is installed so that the surface temperature of the tight adhesion surface 23 can be measured. A pump which is not shown in the figure is operated in this state and a liquid 20 at 20 deg.C is supplied to the pipe 16. On the other hand, the temperature of a spray liquid 28 stored at a water bath 26 is set to 50 deg.C and the spray liquid 28 is sprayed from the nozzle 36 to the adhesion surface 23. The spray liquid 28 enters a retention hole 24 of a liquid film retention member 18 and forms a water film, and spraying is stopped and at the same time, the temperature change of the adhesion surface 23 is measured. Since the liquid film retention member 18 subdivides the spray liquid 28, thus delaying the thermal conduction with an adjacent liquid film and thereby, delaying the temperature change rate of an entire pipe surface. Therefore, a thermal change which cannot be chased by naked eyes can be fully captured, thus the adhesion state of a deposit in the pipe can be grasped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the state of corrosion products and scale adhesion inside pipes and tanks, and more particularly to the surface temperature of pipes and tanks using a non-contact temperature sensor. The present invention relates to a method for measuring a change and detecting a state of adhesion of a corrosion product or a scale generated inside a pipe, a tank, or the like from a state of heat distribution that changes with time.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting internal conditions such as corrosion products in pipes and tanks, scale adhesion, etc., an ultrasonic sensor is attached to a portion where scale is believed to be adhered and measured. , A method of detecting corrosion products and scale adhesion sites from the transmission image using an X-ray transmission device, a method of observing by inserting a fiberscope mirror etc. into the pipe or tank, cutting out a part of the pipe or tank , The method of measuring the state of adhesion of corrosion products and scales by calipers, micrometer, photographs, visual inspection, etc., and the method using a non-contact temperature sensor, the corrosion products and scales formed inside pipes and tanks It should be noted that the temperature transfer speed at that portion differs due to unevenness due to adhesion or the like. As a first measuring method, a fluid having a constant temperature is flown through the object to be measured, and the object is kept at a uniform temperature (steady temperature). After that, a fluid having a temperature different from the steady temperature is caused to flow through the object to be measured, heated or cooled, and the process in which the heat distribution of the pipe surface temperature changes is analyzed. A method of detecting the inner surface state of the measurement object by this analysis is used. As a second measuring method, a fluid having a constant temperature is flown through the object to be measured, and the object is maintained at a uniform temperature (steady temperature). Then, a liquid having a temperature different from the steady temperature is sprayed on the surface of the object to be measured and heated or cooled. Then, the process in which the heat distribution of the pipe surface temperature changes through the liquid film formed on the pipe surface is analyzed. A method of detecting the inner surface state of the measurement object by this analysis is used.

The liquid film formed on the surface of the object to be measured is
Prevents sunlight from directly irradiating the surface of the object to be measured and causing irregular reflection. From this, it is also known that the liquid film has a function of reducing noise during measurement.

[0004]

However, regarding the method using the ultrasonic sensor, since the adhesion site is unknown from the outer surface of the object to be measured, and the ultrasonic sensor also corresponds to a small area, the measuring point is It was necessary to increase. For this reason, a great deal of labor is required, and there is a possibility that measurement omissions at measurement points may occur.

In the method using the X-ray transmission device, the measuring device becomes large in scale, and a high level technique is required for measurement and analysis of the measured data. In addition, there was a fear that the safety might be reduced due to the use of X-rays.

[0006] In the method using the fiberscope mirror or the like, a part of the object to be measured is destroyed, so that there is a possibility that the operation is temporarily stopped or that the field of view is obstructed by a contaminant such as a scale and accurate measurement cannot be performed. It was

In the method using the micrometer and the caliper, the operation of the boiler, the refrigerator or the like must be stopped to stop the piping, so that there is a problem of operation limitation.

In the method of spraying a liquid on the surface of the object to be measured and measuring the change process of the surface temperature of the object to be measured with the non-contact temperature sensor through the liquid film, a temperature difference occurs between the surface of the pipe and the liquid film. In this case, the heat transfer function works and heat transfer occurs between the two. Here, since the liquid film is formed without being partitioned on the surface of the object to be measured, if there is a heat transfer action from the pipe,
The heat transferred to the liquid film diffuses inside the liquid film. Therefore, even if an attempt is made to detect the adhered state of deposits inside the pipe by measuring the heat distribution of the liquid film, the heat distribution of the liquid film is not clear, making it difficult to perform accurate detection. there were. Therefore, there is a problem that the internal state of the pipe cannot be correctly grasped even if the pipe deposit inspection is performed.

The present invention focuses on the problems when using a non-contact temperature sensor, and suppresses the thermal diffusion in the liquid film by dividing the liquid sprayed on the surface of the object to be measured and holding it in small areas. The purpose is to clarify the heat distribution in the film and improve the accuracy of pipe deposit inspection.

[0010]

In order to achieve the above-mentioned object, the present invention provides the above-mentioned measurement in which a liquid film is formed by spraying a liquid on an object to be measured, which is composed of a pipe, a tank and the like, and which changes by heat transfer action. In the pipe adhering matter inspection method, which captures the heat distribution of the surface temperature of the object through the liquid film with a temperature sensor, and detects the distribution of the scale and the like adhering to the inside of the measurement object from the deviation of the heat distribution, the measurement object The liquid film of the liquid is divided into small regions and held on the surface, and the distribution of scale and the like adhering to the inside of the object to be measured is detected from the uneven distribution of the heat distribution of the divided liquid film.

Further, the liquid film holding substance capable of holding the liquid film on the surface of the measurement object is composed of a mesh member having a smaller thermal conductivity than the measurement object and the liquid, and is subdivided by the member. In addition, heat transfer between the liquid films is reduced.

[0012]

According to the above construction, the liquid is divided into small areas on the surface of the object to be measured and held as a liquid film. Then, heat transfer is suppressed between the divided liquid films. Therefore, even if a temperature difference occurs on the surface of the object to be measured and heat is transferred to the liquid film, the diffusion of heat is suppressed, and a clear temperature distribution can be formed. Therefore, when the liquid film is measured by the non-contact temperature sensor, a clear temperature distribution can be captured, and the adhered state of the adhered matter inside the pipe can be grasped.

Further, since the liquid film holding substance for dividing and holding the liquid film into small regions is formed by a mesh member having a smaller thermal conductivity than the measurement object and the liquid to be sprayed, the liquid film holding substance is It is possible to delay the time of heat conduction between adjacent liquid films, suppress the diffusion of heat, and delay the rate of temperature change over the entire surface of the pipe. Therefore, the change in heat, which is difficult to follow with the naked eye, can be sufficiently captured, and the adhered state of the adhered matter inside the pipe can be grasped.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the pipe deposit inspection method according to the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic view of an apparatus for achieving the pipe deposit inspection method according to the present invention. The apparatus as shown in the figure includes an inspection unit 10 that is an inspection measurement object, a spray unit 12 that sprays a liquid onto the inspection unit 10, and a temperature measurement unit that is a non-contact temperature sensor that measures the temperature of the inspection unit 10. 14 and.

The inspection unit 10 includes a pipe 16 as a measurement object,
A liquid film holding member 18 serving as a liquid film holding substance is fixed to the surface of the pipe 16. Although not shown, a pump is connected to the pipe 16 and the water 20 can be poured into the pipe 16 by driving the pump. The pipe 16 is made of carbon steel and has a uniform wall thickness.

The liquid film holding member 18 has a quadrilateral shape, and a fixture 22 having a hook attached to a rubber cord is provided on two sides of the pipe 16 which are parallel to the central axis of the pipe 16. Then, the liquid film holding member 18 is hung on the pipe 16 and the fixtures 22 at both ends are pulled in the same direction, so that the liquid film holding member 18 is tightly fixed to the half circumferential surface of the pipe 16. At this time, the direction of the contact surface 23 of the liquid film holding member 18 is set so as to face the nozzle provided in the spraying section 12 described later. The liquid film holding member 18 is formed of a material having a smaller thermal conductivity than that of the pipe 16 and the spray liquid described later, and has a mesh-like number of holes. The hole serves as a holding hole 24 for holding the spray liquid sprayed from a nozzle described later, and when the spray liquid enters the holding hole 24, the holding hole 24 is restarted from the holding hole 24 by surface tension. The size and shape may be such that it does not flow. In the present embodiment, the size and shape of the holding hole 24 is a quadrilateral whose one side is 1 mm or less.

In the above description, only one liquid film holding member 18 is used for the pipe 16, but in order to enlarge the contact surface 23, a plurality of liquid film holding members 18 are provided on the surface of the pipe 16. May be fixed. Further, the liquid film-holding substance is composed of fine blocks or the like, and the spray liquid is surrounded by the blocks, from the viewpoint that the spray liquid may be divided and held in small areas on the surface of the pipe 16. Hold it in the gap. The spray liquid may be divided into small regions and held by forming the gaps by the block arrangement in this manner.

The spray section 12 is provided with a water tank 26 so that the spray liquid 28 described above can be stored therein. A heater 30 for adjusting the temperature of the spray liquid 28 is attached inside the water tank 26.
The temperature of the spray liquid 28 can be arbitrarily set by the heater controller 32 installed outside. A tube is pulled out from the bottom of the water tank 26 and connected to the suction port of the pump 34. The pump 34
Is provided with a suction port and a discharge port for the spray liquid 28, and a nozzle 36 is attached to the discharge port via a tube. Then, by operating the pump 34, the spray liquid 28 is taken in through the suction port, and the spray liquid 28 is discharged from the nozzle 36.
Can be sprayed.

The temperature measuring unit 14 measures the intensity of the energy of the radiation emitted from the object to be measured and knows the temperature distribution of the object to be measured, and the infrared radiation temperature sensor 38 and the infrared radiation temperature distribution display device 40. Composed of and. The infrared radiation temperature sensor 38 collects the radiation of the object to be measured by a condenser lens and selects a specific wavelength as necessary. Then, the collected radiant energy is converted into an electric signal by the detection element. Also, infrared radiation temperature distribution display device 40
Receives an electric signal from the infrared radiation temperature sensor 38,
The electric signal is amplified, and emissivity correction, linearization, and signal processing are performed. Then, the heat distribution as the measurement result is displayed on the monitor 42 installed in the infrared radiation temperature distribution display device 40 by expression such as color and color density. This display method allows the person in charge of measurement to understand the heat distribution of the object to be measured with a glance at the monitor. The temperature measuring unit 14 configured in this manner is installed so that the surface temperature of the pipe 16 to which the liquid film holding member 18 is attached can be measured.

A procedure for carrying out the method for inspecting pipe deposits in pipes using the above-mentioned apparatus will be described. First, the liquid film holding member 18 made of a heat insulating material is attached to the pipe 16 to be measured.
Are tightly fixed using the fixture 22. And the contact surface 23
The nozzle 36 is faced to and the temperature measuring unit 14 is arranged so that the surface temperature of the contact surface 23 can be measured.

Here, a pump (not shown) is operated to pour water 20 having a water temperature of 20 ° C. into the pipe 16. If this state is continued, the surface temperature of the pipe 16 will be 2
It becomes 20 ° C. which is the same as the water temperature of 0. At this time, the water tank 26
The heater 30 and the heater controller 32 are operated to raise the spray liquid 28 stored in the tank to a water temperature of 50 ° C.

Here, the pump 34 is operated and the nozzle 36
The spray liquid 28 is sprayed on the contact surface 23 for about 10 seconds.
The spray liquid 28 becomes a mist in the air and starts to be applied to the liquid film holding member 18. Then, the spray liquid 28 attached to the liquid film holding member 18 enters the holding holes 24 of the liquid film holding member 18 and is held on the contact surface 23. And spray 2
When the spraying of No. 8 is completed, the spray liquid 28 uniformly enters the holding holes 24 in the contact surface 23, and a water film having a uniform thickness is formed on the contact surface 23. Due to this water film formation, diffuse reflection is suppressed in the pipe 16 made of carbon steel, and the temperature measuring unit 14
Therefore, more accurate measurement becomes possible. Further, since the spray liquid 28 has a temperature 30 ° C. higher than the surface temperature of the pipe 16, spraying on the contact surface 23 temporarily raises the surface temperature of the pipe 16.

FIG. 2 is a surface temperature distribution diagram of the contact surface 23 measured by the temperature measuring unit 14 at a certain moment after the spraying is stopped. As shown in this figure, the surface temperature of the contact surface 23 is not uniform, and there are positions where the temperatures are different as shown in (a), (b), and (c). Further, these temperature distributions have no difference with the passage of time, and after a sufficient time has passed, the temperature returns to the original temperature of 20 ° C. This is because the heat of the spray liquid 28 is removed by the heat exchange with the contact surface 23 with the passage of time.

FIG. 3 shows (a), (b), and FIG.
It shows the temperature with time at the position in (c). As shown in this figure, when the spraying of the spray liquid 28 is stopped at time t ₀ , the surface temperature of the contact surface 23 suddenly drops to the original temperature (20 ° C.) of the pipe 16 after a slight delay. Go. However, without using the liquid film holding member 18, the pipe 16
Compared with the case where the spray liquid 28 is directly sprayed to the surface, the degree of temperature decrease over time is smaller when the liquid film holding member 18 is used, and the phenomenon can be delayed. This is because the spray liquid 28 is subdivided by the holding holes 24 of the liquid film holding member 18, so that the heat transfer action between adjacent water films is reduced. When this state is measured by the temperature measurement unit 14, the heat change, which is hard to follow with the naked eye, is delayed, and thus a sufficient time for detection can be secured.

The delay of the temperature drop occurring on the contact surface 23 and the difference in the temperature drop rates at the positions (a), (b) and (c) are due to the range of adhesion of scale or the like attached to the inside of the pipe 16. This is because the thermal diffusivity of each part of the pipe 16 varies depending on the adhesion thickness and the like. From this, as shown in the figure, the temperature difference 44 occurs within a certain short time range, and the uneven temperature distribution as described above is observed.

FIG. 4 shows the relationship between the thickness of the adhered scale and the like inside the pipe 16 and the outer surface temperature of that portion in the cross section II of FIG. Further, FIG. 5 is a relationship diagram showing the relationship between the thickness of the scale or the like attached to the inside of the pipe and the heat conduction.

As shown in these figures, there is a difference in the temperature distribution of the outer surface that the thicker the scale or the like is, the higher the temperature is, and the thinner the temperature is, the lower the temperature is. This phenomenon occurs because the thermal conductivity of the scale and the like and the specific heat differ from the value of the carbon steel forming the pipe 16.
That is, the scale or the like is a porous body of metal oxide,
The apparent thermal conductivity is close to that of water because water is retained in the pores. Therefore, the heat transfer coefficient is significantly smaller than that of carbon steel as a piping material (the heat conductivity of water and carbon steel is 0.5 kcal / mhr ° C,
37 kcal / mhr ° C), and the specific heat is larger than that of carbon steel (specific heat of water and carbon steel is 1.0 kcal / kg ° C and 0.12 kcal / kg, respectively).
° C). Therefore, the temperature distribution is biased depending on the adhesion state of scales and the like. Then, if the relationship between the thickness of the scale or the like and the outer surface temperature of the object to be measured is collected in advance as data, the temperature change of the pipe 16 to be measured is measured to adhere to the inside of the pipe 16. It is possible to grasp the adhesion status of scales and the like.

FIG. 6 is an enlarged view of the liquid film holding member 18. As described above, the liquid film holding member 18 subdivides the liquid film and holds it in the holding holes 24. From this, the time for heat conduction to the adjacent liquid film can be delayed, which has the effect of delaying the rate of temperature change over the entire surface of the pipe. Therefore, due to this delay effect, it is possible to secure a sufficient time for detecting the adhered matter inside the pipe.

In the present embodiment, the liquid at a temperature higher than the pipe temperature was sprayed to form a water film, and the temperature state change after the spraying was stopped was measured. However, the spray liquid was set at a temperature lower than the pipe temperature,
You may measure a temperature state change. Further, the object to be measured is also a pipe in the present embodiment, but it can be used as an application example in a device such as a tank.

[0030]

As described above, according to the present invention, the liquid is divided into small areas on the surface of the object to be measured and held as a liquid film. Then, heat transfer is suppressed between the divided liquid films.
Therefore, even if a temperature difference occurs on the surface of the object to be measured and heat is transferred to the liquid film, the diffusion of heat is suppressed, and a clear temperature distribution can be formed. Therefore, when the liquid film is measured by the non-contact temperature sensor, a clear temperature distribution can be captured, and the adhered state of the adhered matter inside the pipe can be grasped.

Further, since the liquid film holding substance for dividing and holding the liquid film into small regions is formed by a mesh member having a smaller thermal conductivity than the measurement object and the liquid to be sprayed, the liquid film holding substance is It is possible to delay the time of heat conduction with the adjacent liquid film, suppress the diffusion of heat, and delay the rate of temperature change on the entire surface of the pipe. Therefore, the change in heat, which is difficult to follow with the naked eye, can be sufficiently captured, and the adhered state of the adhered matter inside the pipe can be grasped.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for achieving a pipe deposit inspection method according to an embodiment of the present invention.

FIG. 2 is a surface temperature distribution diagram of a contact surface according to the embodiment of the invention.

FIG. 3 is an explanatory view showing a change in surface temperature according to the embodiment of the invention.

FIG. 4 is an explanatory view showing the relationship between the thickness of the adhered scale and the outer surface temperature in the cross section II of the pipe.

FIG. 5 is a relationship diagram showing a relationship between the thickness of a scale or the like attached to the inside of a pipe and heat conduction.

FIG. 6 is an enlarged view of the liquid film holding member according to the embodiment of the invention.

[Explanation of symbols]

 10 Inspection Part 12 Spraying Part 14 Temperature Measuring Part 16 Piping 18 Liquid Film Holding Member 20 Liquid 22 Fixing Device 23 Adhesion Surface 24 Holding Hole 26 Water Tank 28 Spraying Liquid 30 Heater 32 Heater Controller 34 Pump 36 Nozzle 38 Infrared Radiation Temperature Sensor 40 Infrared Radiation Radiation Temperature distribution display 42 Monitor 44 Temperature difference

Claims (2)

[Claims] 1. A liquid film is formed by spraying a liquid on a measurement object including a pipe, a tank, etc., and the non-contact temperature sensor measures the heat distribution of the surface temperature of the measurement object which changes due to heat transfer action. In the pipe adhering matter inspection method of detecting the distribution of scale and the like adhering to the inside of the measured object from the bias of the heat distribution, the liquid film of the liquid is divided into small areas and held on the surface of the measured object. Then, the distribution of scales or the like adhering to the inside of the object to be measured is detected from the deviation of the heat distribution of the divided liquid film. 2. The liquid film-holding substance capable of holding the liquid film on the surface of the measurement object is composed of a mesh-like member having a smaller thermal conductivity than the measurement object and the liquid, and is subdivided by the member. The pipe deposit inspecting method according to claim 1, wherein heat transfer between the formed liquid films is reduced.