JP5157822B2 - Adherent detection unit and detection apparatus - Google Patents

Description

  The present invention relates to an adhering matter detection unit and a detection device that are preferably used for detecting slime and scale in a circulating water system such as a circulating cooling water system.

  As a method of detecting the increase in the thickness of the microorganism film formed on the wall surface of heat exchangers and pipes due to microorganisms generated in the circulating water such as cooling towers, a material that tends to adhere slime such as rubber plates is used in the circulating water. There is a rubber plate method in which the amount of SS adhering to the rubber plate is measured by periodically dipping the rubber plate and pulling up the rubber plate.

In the case of this rubber plate method, in order to ensure the reliability of the value of the slime amount adhering to the rubber plate, a plurality of rubber plates are immersed in circulating water and immersed for 3 days in order to reduce measurement errors. Since the amount of adhesion at the time when the slime adhesion can be expected to some extent is measured, it takes at least 3 days to judge. In addition, in order to ensure measurement reliability, the rubber plate that has been pulled up does not return to the measurement point again. It must be immersed, and when trying to shorten the time interval , the number of rubber plates increases, and the measurement operation becomes complicated.

  In JP-A-61-26809, the temperature of a heat transfer part measured in advance by a heat-sensing part (thermocouple, etc.) measured by heating a heat-generating part provided inside or outside the pipe is measured. A method is described in which the amount of heat transfer is measured from the fluid temperature in the pipe and the heat transfer inhibition due to a microbial film (slime) or precipitate (scale) attached to the inner wall surface of the pipe is detected from the change in the amount of heat transfer. Yes.

  The method disclosed in Japanese Patent Laid-Open No. 61-26809 is a method for detecting the heat transfer inhibition caused by the deposits adhering to the inner wall surface of the pipe by the temperature rise of the temperature measuring element embedded in the pipe pipe wall. It is a method that can detect adhesion in a short time. However, (1) it is necessary to prepare a measuring unit for measuring the water temperature. (2) It is necessary to prepare a special piping with a temperature sensor embedded in addition to the normal piping. (3) In order to stabilize the heat supply amount to the pipe side by embedding the heating part in the pipe or fixing it outside the pipe, keep the heat radiation outside the pipe constant. It is not easy to prepare a means for measurement.

In Japanese Patent Laid-Open No. 10-332610, a decrease in the amount of heat dissipated by the slime formed on the flat plate is caused by a resistance change when a heater in which a resistor such as platinum is formed in a pattern on the flat plate is heated. Is described by measuring the temperature rise (increase in resistance value). According to this method, a small measuring unit can be immersed in the circulating water system, and the measurement operation is facilitated as compared with the rubber plate method and the method disclosed in Japanese Patent Application Laid-Open No. 61-26809. However, in Japanese Patent Laid-Open No. 10-332610, since the water temperature and the water flow velocity are not measured, it is impossible to distinguish the change in the heat release amount due to the fluctuation of the water temperature or the flow velocity and the change in the heat release amount due to the slime adhesion. It was necessary to provide a means for separately measuring changes in water temperature and flow velocity.
JP 61-26809 A JP-A-10-332610

  As described in Japanese Patent Laid-Open No. Sho 61-26809, piping is measured by a method of measuring the amount of heat radiation from the output of the temperature measuring element embedded in the piping when the heater is heated and the temperature of the fluid flowing in the piping measured in advance. It is possible to always detect deposits on the wall surface. According to Japanese Patent Laid-Open No. 10-332610, it is possible to realize a measuring means that is small and does not require special piping. However, these methods are difficult to distinguish between temperature fluctuations due to deposits and fluctuations due to flow velocity when the heat dissipation due to flow velocity changes due to flow velocity fluctuations, and reduce the influence of water flow for stable measurement. There is a need. In particular, when using the measuring means of JP-A-10-332610, when the flow of water directly hits the measuring means, it is directly affected by the change in the water flow velocity.

  An object of the present invention is to solve the above-described problems of the prior art and to provide a deposit detection unit and a detection apparatus that can detect deposits with high accuracy.

The attached matter detection unit according to claim 1 is a probe in which a heating element and a temperature measuring element are inserted into a metal tube, and a filler is filled between the heating element and the temperature measuring element and the inner surface of the metal tube; A flow cell in which the probe water is configured to be in contact with the test water, and a pair of lead wires for energizing the heating element. Of the pair of lead wires, one lead wire is led out of the metal tube in an insulated state with respect to the metal tube, and the other lead wire is connected to the metal tube. It is connected to the inner surface, and another lead wire is connected to the metal tube, and energization to the heating element is performed by the one lead wire, the other lead wire, the metal tube, and the other lead. It is performed through a line .
According to a second aspect of the present invention, there is provided the adhering matter detection unit according to the first aspect, wherein one end of the metal tube in the axial direction of the tube is held by the flow cell, and the other distal end of the axial direction of the tube is It is arrange | positioned in a flow cell, In this flow cell, this metal tube is arrange | positioned toward the downstream of the water flow direction of this test water, It is characterized by the above-mentioned.
According to a third aspect of the present invention, there is provided the adhering matter detection unit according to the first or second aspect, wherein the flow cell includes a straight tubular main pipe portion and a short tubular shape projecting laterally from the middle of the main pipe portion in the tube axis direction. A holder holding the probe is inserted into the main pipe portion from one end side in the tube axis direction of the main pipe portion, and the insertion direction of the holder into the main pipe portion The metal tube protrudes from the tip of the main tube into the main tube, and the probe is arranged at an axial center in the main tube.
According to a fourth aspect of the present invention, there is provided the adhering matter detection unit according to the third aspect, wherein the holder is fixed to the flow cell with a packing and a nut attached to the one end side of the main pipe portion. The nut is disposed so as to close between the one end side and the holder, and the nut is attached to the main pipe portion so as to hold the packing.
The deposit detection unit according to claim 5 is the deposit detection unit according to claim 3 or 4, wherein the metal tube of the probe is located closer to the other end side in the tube axis direction of the main tube than the branch tube in the main tube. It is located, The said holder faces the said branch pipe part, It is characterized by the above-mentioned.
The adhering matter detection unit according to claim 6 is the adhering water detection port according to any one of claims 3 to 5, wherein an inlet of the test water is provided at an end portion of the branch pipe portion opposite to the side connected to the main pipe portion. Provided, and an outlet for water to be detected is provided on the other end side of the main pipe portion.

The attached matter detection apparatus according to claim 7 is an attached matter detection unit according to any one of claims 1 to 6 , an energization control means for the heating element of the attached matter detection unit, and the attached matter detection unit. A temperature measuring unit that measures the temperature of the heating element when the amount of current applied to the heating element is changed. It is characterized in that the adhesion of the deposit on the outer surface of the metal tube is determined based on the change of the above.

The foreign substance detecting device according to claim 8, in claim 7, after the constant current i ₁ to the heating element for a predetermined time t ₁ current, or a predetermined time t ₂ only de-energized, or, a predetermined time t ₂ The cycle of setting a constant current i ₂ smaller than the constant current i ₁ is repeated, and adhesion of the deposit on the outer surface of the metal tube is determined.

The deposit detection apparatus according to claim 9 is characterized in that, in claim 8 , the measured temperature T _{1 of the} temperature measuring body at the start of the predetermined time t ₁ or at the end of the predetermined time t _{2 and} the end of the predetermined time t ₁ or based on the temporal change of the temperature difference between the measured temperature T ₂ of the temperature sensing element at the beginning of said predetermined constant-time t _2, it is characterized in determining the adhesion of the deposit to the metal tube outer surface.

A deposit detection apparatus according to a tenth aspect of the present invention is characterized in that, in any one of the seventh to ninth aspects, a pump is provided for passing the test water through the flow cell in a fixed amount.

  In the adhering matter detection unit and apparatus of the present invention, a probe in which a heating element and a temperature measuring element are installed inside a metal tube is installed in the flow cell. The test water is passed through the flow cell and brought into contact with the probe, and the amount of current supplied to the heating element is increased or decreased at regular intervals. Then, the temperature depending on the water temperature is measured when the energization amount is zero or reduced, and the temperature depending on the heat generation amount is measured when the energization amount is increased. This makes it possible to measure the water temperature and the internal temperature at the time of heat generation with a single sensor, detect the adhesion of the deposit on the probe based on this, and accurately detect the occurrence of slime in the water system. .

  In the present invention, the amount of heat released from the probe depends only on the temperature of the water by quantitatively passing the test water through the flow cell by the pump. For this reason, the internal temperature depending on the water temperature when the energization amount is zero (or reduced) and the internal temperature depending on the heat generation when the energization amount is increased are measured, and the difference between these two temperatures is measured. If calculated, it is possible to accurately detect an increase in internal temperature that increases due to heat transfer inhibition due to slime adhesion.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a sectional view of an adhering matter detection unit according to the embodiment, and FIG. 2 is a sectional view in the longitudinal direction of a probe used in this unit.

  First, the configuration of the probe will be described with reference to FIG. The probe 1 includes a metal tube 2 made of a corrosion-resistant metal such as brass and stainless steel whose base end side is open and its distal end side is closed, a heating element 3 and a temperature measuring body 4 disposed in the metal tube 2, and a metal tube 2. It has a filler 5 such as electrically insulating and thermally conductive magnesium oxide (magnesia) particles filled in a space between the inner peripheral surface and the heating element 3 and the temperature measuring element 4. The proximal end side of the probe 1 is sealed with a resin 6 such as an epoxy resin.

  The thickness of the metal tube 2 is preferably about 0.05 to 0.5 mm. The diameter of the metal tube 2 is preferably about 2 to 5 mm.

  As the heating element 3, a material in which a platinum thin film is formed on an insulating substrate is suitable. As the temperature measuring element 4, a thermocouple, a thermistor, or the like is suitable. However, the heating element 3 and the temperature measuring element 4 may be other than these.

  The heating element 3 is preferably disposed at the axial center of the metal tube 2. The temperature measuring body 4 is preferably provided so as to be in contact with the inner peripheral surface of the metal tube 2 between the heating element 3 and the inner peripheral surface of the metal tube 2.

Of the lead wires 3a and 3b for energizing the heating element 3, one lead wire 3a extends to the outside of the probe 1, and the other lead wire 3b is connected to the metal tube 2 by soldering or the like. through it is conducting the leads 3c. The lead wire 3c is connected to the base end of the metal tube 2 by soldering or the like. Two lead wires 4 a and 4 b from the temperature measuring body 4 are drawn out of the probe 1. These lead wires are provided with an insulating coating.

  FIG. 1 is a sectional view of an adhering matter detection unit 10 in which the probe 1 is provided in a flow cell 11. The flow cell 11 includes a straight tubular main pipe portion 12 and a short tubular branch pipe portion 13 projecting laterally from the middle in the longitudinal direction of the main pipe portion 12. A tubular holder 14 is inserted from the rear end portion of the main pipe portion 12, and the probe 1 is attached to the tip of the holder 14. A metal tube 2 of the probe 1 protrudes from the tip of the holder 14 into the flow cell 11. The probe 1 is disposed at the axial center position in the main pipe portion 12.

  The holder 14 is fixed to the flow cell 11 by a packing 15 and a nut 16. The tip of the metal tube 2 of the probe 1 is located on the front end side (upper end side in FIG. 1) of the main tube portion 12 with respect to the branch tube portion 13. A holder 14 faces the branch pipe portion 13.

  A test water inlet 17 is provided at the tip of the branch pipe 13 opposite to the side connected to the main pipe 12, and a test water outlet 18 is provided at the front end of the main pipe 12. .

  The adhering matter detection apparatus includes an energization control unit for the heating element 3 of the probe 1 and a determination unit that processes the output signal of the temperature measuring element 4 to determine the adhering state of the adhering matter. The circuit configuration of the attached matter detection apparatus will be described with reference to FIG.

  The attached matter detection device includes a current output unit 21 that outputs a current to the heating element 3, a temperature input unit 22 that inputs a temperature signal from the temperature measuring body 4 and converts it into a digital signal, and a temperature input unit 22 A signal is input to calculate a current value to be output by the current output unit 21 based on temperature information of the temperature measuring element, and a calculation unit 23 that performs slime adhesion determination. The arithmetic unit 23 is an arithmetic processing circuit configured by a microcomputer (μ-CPU) or a large scale integrated circuit (LSI). The calculation unit 23 periodically increases the value of the energization current to the heating element 3, and based on the temperature data from the temperature measuring element 4, the increase in the heat transfer resistance generated by the deposits attached to the surface of the probe 1. Judgment status of deposits is determined.

  In order to observe the generation state of the slime in the water system using this adhering matter detection device, the test water from the water system is passed through the flow cell 11 at a constant flow rate by a pump or the like. Then, as shown in FIG. 4, the heating element 3 is energized in pulses, the measured temperature of the temperature measuring element 4 is detected, the amount of slime attached to the probe 1 is determined based on this result, and the slime in the water system The occurrence status (ease of occurrence) of the event is determined.

As shown in FIG. 4, when energization of the heating element 3 is started, the heat generated by the heating element 3 is transferred to the temperature measuring element 4, whereby the temperature detected by the temperature measuring element 4 starts to rise from T ₁ . The temperature detected by the temperature measuring element 4 rises until the amount of heat generated from the heating element 3 and the amount of heat released from the surface of the probe 1 are balanced.

The energization time t ₁ is selected so that the temperature detected by the temperature measuring element 4 is sufficient to reach the equilibrium temperature T ₂ . The time t ₁ may be determined by performing a pre-operation test. However, if t ₁ is excessively long, the real-time property of the measurement becomes poor, so the temperature rises to a temperature that can be substantially regarded as an equilibrium temperature (for example, a temperature at which the difference from the final equilibrium temperature is within 0.1 ° C.). the time required for temperature may be set as t _1. For normal, _{t 1} is preferably about 5 to 60 seconds, especially 5 to 20 seconds.

When the energization of the heating element 3 is stopped, the temperature detected by the temperature measuring element 4 starts to decrease by radiating heat from the probe 1 to the surrounding water. The energization-stopping time period t _2, previously selected as the detected temperature of the temperature sensing element 4 even if the slime is attached to the probe 1 is sufficient time to reach approximately equal equilibrium temperature T ₁ of the ambient temperature . The time t ₂ may be determined by performing a pre-operation test. However, if too long a t _2, since the real-time measurement becomes poor, required to decrease to a temperature which can be regarded as substantially equilibrium temperature (e.g., temperature difference between the water temperature is within 0.1 ° C.) time may be set as t _2. Usually, t2 is preferably about ₂₀ to 300 seconds, particularly about 60 to 300 seconds.

In the fourth drawing are zero energization amount at t ₂ hours period, but may be energized a constant current i ₂ traces than the current amount i ₁ of t ₁ hour period. However, i ₂ = 0 is preferable.

If the water temperature of the water does not vary, when no adhered slime probe 1, both the one energization time t ₁ before the start of the measurement temperature T _1, and the measured temperature T ₂ of the current supply time t ₁ the end is Constant over time. It is preferable to set the amount of current supplied to the heating element 3 so that the difference between T ₂ and T ₁ is of the order of 5 to 20 ° C..

In a state where slime adheres to the probe 1, the measured temperature T _{2 at the} end of the energization time t ₁ is higher than when the slime does not adhere to the probe 1. This is because heat transfer from the probe 1 to water is inhibited by slime, and the detailed mechanism will be described next.

Accordingly, the temperatures T ₁ and T ₂ are measured over time while the pulse energization shown in FIG. 4 is repeated, and the change from T ₁ and T ₂ (T ₂ −T ₁ ) over time to the probe 1 is measured. It is possible to detect the presence and amount of slime adhesion.

A calculation formula for obtaining the adhesion thickness of the slime from the above temperatures T ₁ and T ₂ is as follows. This equation is based on the heat transfer model shown in FIG.

In FIG. 5, Tw (water temperature) is _{T 1.} Ts (sensor surface temperature), when the thermal conductivity of the internal sensor is smaller in negligible compared to kf can be a value equal to T _2. The items on the right side other than Tw and Ts are constants obtained from the shape of the sensor, the resistance value of the heating element, the energization amount, and the like.

For example, for the heat flux q, the electrical resistance value R of the heating element 3, the energization current value i to the heating element 3, the length L of the heating element 3 in the probe longitudinal direction, and the radius r ₁ of the metal tube 2 are Can be calculated.

Thus, by measuring the T ₁ and T _2, it is possible to measure the thickness of the slime (sensor surface deposits).

  However, in order to consider the laminar boundary film heat transfer coefficient as a constant, the thickness of the laminar boundary film needs to be constant. For this purpose, water is passed through the flow cell 10 at a constant flow rate by a metering pump or the like. Water is preferred. In addition, it is good also considering the flow rate as the speed value which can ignore the fluctuation | variation of a laminar boundary film heat transfer coefficient. Instead of the metering pump, a control valve for making the flow rate constant may be used.

  FIG. 6 is a system diagram of an open-type circulating cooling water system provided with this deposit detection device.

The water in the cooling tower 30 returns to the cooling tower 30 through the pipe 31, the pump 32, the pipe 33, the heat exchanger 34, and the pipe 35, and the water in the pit of the cooling tower 30 passes through the sampling pipe 36 and the metering pump 37. And introduced into the flow cell 11 from the inlet 17 of the deposit detection unit 10. This water is returned to the pit via the outlet 18 and the pipe 38 after coming into contact with the probe 1. The slime generation state in the circulating cooling water system is detected by the detected temperatures T ₁ and T _{2 of the} probe 1.

[Example of sensor production]
A metal film resistance 120Ω of φ1.7 × 4.0 mm was installed as a heating element 3 at the tip of a stainless steel metal tube 2 having a diameter of 3.0 mm, a wall thickness of 0.1 mm, and a length of 35 mm. Further, in the vicinity of the heating element 3, a thermocouple as a temperature measuring body 4 was disposed so as to contact the inner peripheral surface of the metal tube 2. A magnesium oxide powder having an average particle size of about 100 μm was filled between the inner peripheral surface of the metal tube 2 and the heating element 3 and the temperature measuring element 4. The base end of the metal tube 2 was sealed with an epoxy resin 6. The probe 1 was attached to the tip of the holder 14. The protruding length of the probe 1 from the holder 14 is 18 mm.

  The holder 14 was attached to the flow cell 11 as shown in FIG. 1 and connected as shown in FIG. The inner diameter of the main pipe portion 12 of the flow cell 11 is 20 mm, the length is 120 mm, the inner diameter of the branch pipe portion 13 is 20 mm, the length is 30 mm, and the outer diameter of the holder 14 is 18 mm.

The flow cell 11 with the probe 1 was connected to the cooling tower 30 through a pipe and a metering pump 37 as shown in FIG. 6, and water was passed at a water flow rate of 400 cm ³ / min. By this water flow, the flow of the test water along the surface of the metal tube 2 of the probe 1 becomes a turbulent flow, and heat is uniformly transferred from the surface of the metal tube 2 to the water.

The heating element 3 of the probe 1 was energized at t ₁ = 60 sec, t ₂ = 60 sec, and a current value i = 40 mA during energization. FIG. 7 shows the change with time of T ₂ -T ₁ .

As shown in FIG. 7, T ₂ -T ₁ increased at a rate of 0.05 ° C./day. In parallel with this measurement, the rubber plate was immersed in the cooling water in the pit and the amount of slime deposited was measured. As a result, the amount of slime deposited increased by 10 mg / dm ² over 3 days. From this result, it was recognized that the amount of slime adhesion can be quantitatively detected based on the change with time of T ₂ -T ₁ .

It is sectional drawing of the flow cell of the deposit | attachment detection apparatus which concerns on embodiment. It is sectional drawing of the probe of the deposit | attachment detection apparatus which concerns on embodiment. It is a circuit block diagram of an embodiment. It is an electricity supply pattern and a temperature change pattern figure. It is a temperature distribution map near a pipe wall. It is a systematic diagram of a circulating cooling water system. It is a graph which shows measured temperature.

Explanation of symbols

1 Probe 2 metal pipe 3 heating body 4 temperature sensing element 5 filler 10 attached matter detection unit 11 flow cell 12 main pipe 13 branch pipe part 14 the holder 15 packing 17 inlet 18 outlet 30 the cooling tower 34 heat exchanger 37 metering pump

Claims (10)

A probe in which a heating element and a temperature measuring element are inserted into a metal tube, and a filler is filled between the heating element and the temperature measuring element and the inner surface of the metal tube;
The test water is configured to flow inside, and the flow cell in which the probe is installed to come into contact with the test water;
Equipped with a,
A pair of lead wires for energization is connected to the heating element, and one lead wire of the pair of lead wires is drawn out of the metal tube in an insulated state with respect to the metal tube. The other lead wire is connected to the inner surface of the metal tube, and another lead wire is connected to the metal tube,
The adhering matter detection unit is characterized in that energization of the heating element is performed through the one lead wire, the other lead wire, the metal tube, and the other lead wire . The metal pipe according to claim 1, wherein one base end side in the tube axis direction is held by the flow cell, and the other tip side in the tube axis direction is disposed in the flow cell.
In the flow cell, the metal tube is disposed with the tip side facing the downstream side in the water flow direction of the test water. In Claim 1 or 2, the flow cell has a straight tubular main pipe part and a short tubular branch pipe part projecting laterally from the middle of the tube axis direction of the main pipe part,
A holder holding the probe is inserted into the main pipe portion from one end side in the tube axis direction of the main pipe portion,
The metal pipe protrudes into the main pipe from the tip in the insertion direction of the holder into the main pipe,
The probe is disposed at an axial center position in the main pipe portion. In claim 3, the holder is fixed to the flow cell by a packing and a nut attached to the one end side of the main pipe portion,
The packing is disposed so as to block between the one end side of the main pipe portion and the holder,
The adhering matter detection unit, wherein the nut is attached to the main pipe so as to hold the packing. In Claim 3 or 4, the metal tube of the probe is located in the other end side of the main pipe part in the direction of a pipe axis of the main pipe part in the main pipe part,
The attached matter detection unit, wherein the holder faces the branch pipe portion. 6. The test water inflow port according to claim 3, wherein an inflow port of test water is provided at an end portion of the branch pipe portion opposite to the side connected to the main pipe portion, and the other end of the main pipe portion. An adhering matter detection unit characterized in that an outlet for water to be tested is provided on the side. The deposit detection unit according to any one of claims 1 to 6 ,
Energization control means for the heating element of the deposit detection unit;
A determination means for performing adhesion determination of the deposit on the outer surface of the metal tube from the measured temperature of the temperature measuring body of the deposit detection unit;
An attached matter detection apparatus that determines adherence of an attached matter to the outer surface of the metal tube based on a change in temperature measured by the temperature measuring member when the amount of current supplied to the heating element is changed. According to claim 7, wherein after the heating element constant current i ₁ and the predetermined time t ₁ current, or a predetermined time t ₂ only de-energized, or, the predetermined time t ₂ only constant current i is smaller than _first constant current i A deposit detection apparatus characterized by repeatedly performing a cycle of ₂ to determine whether deposits adhere to the outer surface of the metal tube. In claim 8, the measured temperature T ₁ of the temperature sensing element at the beginning or said predetermined end of constant-time t ₂ of said predetermined constant-time t _1, measuring at the start of the end or said predetermined constant-time t ₂ of said predetermined constant-time t ₁ based on the temporal change of the temperature difference between the measured temperature T ₂ of the temperature sensing element, the foreign substance detecting device characterized by determining the adhesion of the deposit to the metal tube outer surface. In any one of claims 7 to 9, the foreign substance detecting device characterized by comprising a pump for passing water a test water with the metering to the flow cell.

Images