JP2878061B2 - Dirt management method for heat exchanger cooling pipe and dirt management device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dirt management method and a dirt management device for a heat exchanger cooling pipe, and more particularly to real-time monitoring of the degree of dirt removal such as slime formed on the cooling pipe surface and cooling by excessive washing. The present invention relates to a dirt management method and a dirt management device for a heat exchanger cooling pipe, which can minimize corrosion due to damage to a protective coating of the pipe.

[0002]

2. Description of the Related Art In a heat exchanger cooling pipe using seawater, iron vesicles supplied by sea ions in the cooling water, mud in the sea soil, and iron ions supplied as an anticorrosive agent for the cooling pipe adhere to the inner surface of the cooling pipe, and the equipment is installed in the cooling pipe. There is a problem that the heat transmission coefficient decreases. Among such dirt, the problem is the adhesion of marine organisms in the summer, especially when the power demand is tight in the summertime power equipment, the dirt adheres to the inner surface of the cooling pipe, and the power generation efficiency decreases. Invite. The sticky dirt containing such marine organisms is generally called slime. To remove the slime, it is necessary to appropriately perform ball washing, brush washing, or jet washing. However, brush cleaning and jet cleaning require a temporary (several days) suspension of equipment, and ball cleaning that does not require suspension of equipment is mainly performed in summer. However, excessive cleaning by ball cleaning
The protective coating of the cooling pipe, especially the protective coating of the copper alloy member, will be destroyed, and turbulence in the water will cause an inlet attack at the entrance of the cooling pipe in a corrosive environment. In some cases, the equipment suddenly stops due to penetration. Therefore, cleaning must be kept to a minimum.

[0003] Incidentally, as a method of grasping dirt, a method utilizing the degree of vacuum deviation has conventionally been adopted. However, in this method, when dirt adheres to the cooling pipe, the heat transmission coefficient decreases, and a power plant or the like is deteriorated. This is a method of grasping the state of contamination from the degree of vacuum deviation value by using the influence on the degree of vacuum on the steam side of the equipment. Such a vacuum degree deviation is a value of (actually measured vacuum degree)-(expected vacuum degree), and the expected vacuum degree is obtained by calculation for each equipment based on the capacity of the equipment, cooling water temperature, cooling water amount, and the like.

However, the degree of vacuum deviation conventionally used varies depending on the power generation load, and also includes the temperature of the cooling water and the efficiency of the cooling equipment. There is a drawback that it cannot be extracted and managed. Therefore, since the effect of the cleaning cannot be controlled in the ball cleaning, it is a current situation that the cleaning is empirically determined to be performed 10 or 20 times per one cooling pipe.

There is also known a method in which the natural potential of the cooling pipe is detected and the cleaning device is activated when the value becomes larger than a preset value (JP-A-2-157599 and JP-A-4-278198). ).

[0006] In these methods, since the detected natural potential may become larger than the set value not only due to the slime of the dirt but also due to corrosion products such as patina formed on the surface of the cooling pipe, it is not always possible to detect only the dirt. There is a disadvantage that. Further, in these methods, it is necessary to obtain a reference value from experiments and analysis in advance, but it is necessary to obtain the reference value not only for each facility, but also for the same facility if the reference value is not determined again due to changes in the environment due to seasonal changes. There is the complexity that data cannot be obtained.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves these problems of the prior art, enables optimal cleaning, prevents the destruction of the protective film due to excessive cleaning, provides a standard for cleaning, and provides a reference value. It is an object of the present invention to provide a simple method for managing dirt of a heat exchanger cooling pipe and a dirt management device which does not require a heat exchanger.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to control the degree of slime contamination and the degree of removal of slime in cooling water by a change due to an electric current or an electric current by using a conventionally used cathodic protection device. Is achieved by doing

That is, the method for managing contamination of a heat exchanger cooling pipe according to the present invention comprises a potential measuring device and a DC power supply with constant potential control so that the cooling pipe has a constant potential through the cooling water from an electrode provided in the cooling water. When the current is reduced and the current reduction rate after a fixed interval is reduced to zero or zero, the decrease in the current flowing with the removal of the dirt adhering to the inner surface of the cooling pipe is measured. When the approach is determined by the current determination device, the cleaning device for the cooling pipe is turned off.

The present invention also provides a dirt management apparatus for a cooling pipe of a heat exchanger, comprising: an electrode provided in cooling water; a potential measuring device for applying a current from the electrode so that the cooling pipe has a constant potential; A DC power supply unit, a current detection device that measures the value of the energizing current, and a ball cleaning device that is turned off when the detected current reduction rate after a fixed interval is zero or approaches zero.
And a current judging device for outputting a control signal.

[0011]

It is known that when slime is formed on the inner surface of the cooling pipe, the cathode reaction increases due to the catalytic action of the slime. That is, FIG. 1 shows a polarization curve before and after washing depending on the presence or absence of slime in the cathodic protection device.

Here, the conduction potential is set to a potential d near the generation of H _2.
If the value is set to more noble c, the current changes from a to b according to the cleaning. In the present invention, the determination is made by determining the current reduction rate.

[0013]

An embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a configuration diagram showing a state in which the dirt management device of the present invention is applied to a cooling pipe of a heat exchanger. In FIG. 2, 1 is an energizing device, 2 is a ball cleaning device, 3 is an energizing electrode, and 4 is an energizing electrode. The reference electrode, 5 is a cooling pipe, 6 is a water chamber, 7 is a drain negative point, 8 is a negative point for measuring potential, 9 is a current circuit (DC power supply), 10 is a constant potential detecting circuit and a potential measuring circuit (potential Measuring device), 11 is a current detecting device, 12 is a current determining device, 13 is a screen, 14 is a ball collector, 15 is a control panel, 16 is a pump, 17 is an injection nozzle, 18 is a circulating water pipe, and 19 is a pipe. The plates are shown respectively.

In FIG. 2, the cooling pipe 5 is an aluminum brass pipe, and both sides thereof are connected to a water chamber 6 of a steel sheet lined on the inner surface and a circulating water pipe 18 for guiding cooling water.
The tube sheet 19 is also made of insulated neval brass. Insulation coating is applied to the tube sheet surface and the inner wall of the water chamber other than this cooling pipe,
Further, it is necessary to avoid errors such as measurement of other potentials. A conducting electrode 3 provided in a water chamber 6, a discharge minus point 7 of a condenser, and a reference electrode 4 for merely measuring a potential;
A minus point 8 for potential measurement is provided on the tube sheet 19.

The power supply device 1 is a current circuit (DC power supply device)
9, a constant potential detecting circuit and a potential measuring circuit (potential measuring device) 10. This energizing device can also be used as an anticorrosion device using an external power supply system, receives a signal for starting ball cleaning in the existing anticorrosion device, displays the change in current in real time, and indicates that the reduction rate is less than a predetermined value. When this happens, monitoring can be performed by adding a device that outputs a signal indicating the end of ball cleaning to the ball cleaning device.

A direct current is passed from the electrode 3 to the cooling pipe 5 through seawater. A reference electrode 4 for detecting the potential of the cooling pipe 5 is provided on the tube sheet 19, and a constant potential detection circuit and a potential measurement circuit (potential measurement device) 10 are provided so that the current changes so that the conduction potential becomes constant. is there. This reference electrode is placed near the cooling pipe because accurate potential measurement is required.

The ball cleaning device 2 includes a screen 13,
It comprises a ball collector 14, a control panel 15, a pump 16, and an injection nozzle 17.

At the start of ball cleaning, a control signal is sent from the control panel 15 to the current judging device 12 to start monitoring. As the slime is removed, the potential becomes constant by constant potential control, but the current decreases. This current value is measured by the current detection device 11, and the change in the current is measured by the current determination device 1.
In step 2, the decrease in current is monitored in real time. When the decrease rate becomes equal to or less than a certain value (the decrease curve is flat), a signal for ending the ball washing is sent from the current detecting device 11 to the ball collector 14, and the washing is ended.

FIG. 3 shows a change in the current supplied during the ball washing when the monitoring apparatus is actually applied to a heat exchanger cooling pipe. FIG. 4 shows changes in the degree of vacuum deviation conventionally used.

FIG. 3 shows that the energizing current decreases as the ball is washed. On the other hand, with the degree of vacuum deviation in FIG. 4, the degree of vacuum deviation decreases during the ball cleaning, which results in an unnatural result.

In FIG. 3, (a) shows the case where the ball washing is stopped when the slime removal is completed. After the stop, the current gradually increases as the slime adheres. On the other hand, when the ball cleaning is not stopped as in (b), the current suddenly increases because the protective film starts to break down beyond the limit point. This reduction rate is as follows. Reduction rate =
(29.277-28.250) A / 30 min = 0.03
4

[0022]

As described above, according to the present invention, the optimum cleaning can be performed, the destruction of the protective film due to the excessive cleaning can be prevented, and the cleaning can be estimated. Further, in the present invention, since it is not necessary to compare the measured value with the reference value, no labor is required for obtaining the reference value, and there is no need to judge the accuracy of the obtained reference value.

[Brief description of the drawings]

FIG. 1 is a graph showing changes in current voltage and potential before and after washing.

FIG. 2 is a configuration diagram showing a state in which the dirt management device of the present invention is applied to a cooling pipe of a heat exchanger.

FIG. 3 is a graph showing a change in an energizing current during ball cleaning.

FIG. 4 is a graph showing a change in a degree of vacuum deviation during ball cleaning.

[Explanation of symbols]

1: energizing device, 2: ball cleaning device, 3: energizing electrode,
4: Reference electrode, 5: Cooling pipe, 6: Water chamber, 7: Negative discharge point, 8: Negative point for potential measurement, 9: Current circuit (power supply device), 10: Constant potential detection circuit and potential measurement circuit ( 11: current detector, 12: current detector, 13: screen, 14: ball collector, 15: control panel, 16: pump, 17: injection nozzle, 18: circulating water pipe, 19: Tube sheet.

Claims (2)

(57) [Claims] An electric current is applied by using a potential measuring device and a DC power supply device with a constant potential control so that the cooling pipe has a constant potential through the cooling water from an electrode provided in the cooling water, and adheres to an inner surface of the cooling pipe. The current detecting device measures the decrease in the energizing current accompanying the continuation of the removal of the contaminants, and when the current determining device determines that the current reduction rate after the regular interval is zero or approaches zero, the cooling is performed. A dirt management method for a heat exchanger cooling pipe, comprising turning off a pipe cleaning device. 2. An electrode provided in cooling water, a potential measuring device and a DC power supply device with a constant potential control for supplying a current from the electrode to the cooling pipe so as to have a constant potential, and a current detection device for measuring a supplied current value. A heat exchanger comprising: a device; and a current judging device that outputs a control signal for turning off the ball cleaning device when the detected current reduction rate after the detected regular interval becomes zero or approaches zero. Cooling pipe dirt management device.