JPS5955328A - Control device of foreign matter removing device - Google Patents

Abstract

PURPOSE:To perform surely an operation for removing foreign matters, by discriminating the clogging rate of a filter by detecting a deformation extent of the filter, and controlling the operation for removing foreign matters. CONSTITUTION:A foreign matter removing device incorporating with a filter is installed in a cooling water inlet system 2 of a condenser 1 to catch foreign matters by the surface of the filter in the removing device, thereby removing the foreign matter 50 together with a water flow from a discharging system 5 by producing a swirling vortex flow. And, a strain gauge 30 is attached to the inner surface of the filter to measure a deformation extent produced by a pressure difference between the inner and outer surfaces of a filter element 14, and the deformation extent of the element 14 is measured by the gauge 80 to transmit the result to a strain signal converter 83 by a lead wire 81 thereby transmitting it to a control device 60. As a result, the operation for removing the foreign matters is surely performed without being affected by a dynamic pressure caused by a water flow in the foreign matter removing device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a foreign matter removal device used in a tubular heat exchanger such as a condenser, which effectively separates foreign matter such as aquatic organisms in cooling water from a cooling water system.

In thermal and nuclear power plants that use seawater or river water, screens are installed at the water intake to prevent foreign matter such as aquatic organisms in the cooling water from flowing into the condenser. A foreign matter removal device with a built-in filter is often installed in the

For example, in the example shown in FIG. 1, a foreign matter removal device 4 is installed in the inlet system z in front of the condenser 1, foreign matter 50 is captured on the outer surface of the filter 14 in the device, and foreign matter is removed from the discharge system 5 along with the water flow. remove.

In the foreign matter removal device 4, the casing 10 and the filter element 14 have a conical cylindrical shape, and when the filter captures a large amount of foreign matter, the pressure difference between the inlet side and the outlet side of the filter increases compared to before the foreign matter is captured. Differential pressure gauge 40
is detected and transmitted to the control device 60.

The large mouth valve 20 is a butterfly type stop valve and is fully open during normal operation, and the blowdown valve 30 is fully closed during normal operation.

To remove foreign objects, close the artificial valve halfway as shown in Figure 2, change the angle of inflow of cooling water into the foreign object removal device, create a swirling water flow, and utilize the floating phenomenon caused by the swirl.
After separating the foreign matter trapped by the filter filter (surface), the blowdown valve is opened and the foreign matter is discharged out of the casing along with a stream of water.

When the condenser heat load is small, in order to reduce the discharge flow rate of the cooling water circulation pump 6, the blade angle is set to a small angle by the control signal 74 of the pump control device 70 and the pump is operated. As a result, the water flow rate is small, so the filter element 1
Even if the foreign matter clogging rate is the same, the differential pressure at No. 4 is a smaller value than when operating at maximum flow rate, as shown in FIG. In many cases, clogging is determined by

In this way, clogging of the filter element is detected, and if a certain set value is exceeded, foreign matter removal operation is started.

In the known example, clogging is detected by measuring the differential pressure before and after the filter element, but the differential pressure loss of the filter element itself is approximately 8001111+1 without clogging.
Aq, foreign matter removal operation start setting value is approximately 1200 +mAq
Although the difference is minute, dynamic pressure such as pulsation due to turbulent flow inside the foreign matter removal device is often detected at the differential pressure detection point. It is often difficult to determine the presence or absence.

In particular, when the amount of circulating water decreases and a correction calculation is performed to make a determination, it is necessary to further determine the minute differential pressure, and with conventional technology it is difficult to reduce the influence of dynamic pressure beyond a certain level. The drawback was that it was difficult to properly determine the ratio. This means that even if the clogging rate is smaller than the specified value, foreign matter removal operation will be performed frequently, which not only wastes the driving power of the large mouth valve and blowdown valve, but also removes the cooling water along with the foreign matter removal. This reduces the flow rate to the condenser, resulting in a decrease in condenser performance. This discharge of the amount of cooling water is generally as large as 5 to 10%, resulting in a large drop in performance, and in order to compensate for this, the discharge amount of the cooling water circulation pump may be increased, which further increases power consumption. Furthermore, in order to select the appropriate differential pressure detection point that is least affected by dynamic pressure through actual on-site trial operation, multiple detection units may be installed and manufactured in advance, which increases production costs and increases on-site adjustment. It also had the disadvantage of being forced to.

The purpose of the present invention is to detect an appropriate foreign matter capture rate when foreign matter is captured on the filter surface of a foreign matter removal device, regardless of the amount of water flow, and to
An object of the present invention is to provide a control device that performs a foreign matter removal operation.

The main point of the present invention is that when a pressure difference occurs on the filter surface of a foreign matter removal device, the filter deforms according to the pressure difference, and this deformation is not affected by dynamic pressure. The amount of deformation of the filter is detected, the clogging rate of the filter is determined, and the foreign matter removal operation is controlled.

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 4 shows the configuration of the control device of the present invention.

A foreign matter removal device 4 is installed in the cooling water inlet system 2 of the condenser 1, and the foreign matter is captured by the filter surface in the foreign matter removal device 4, causing a swirling vortex flow, and the foreign matter 50 is removed from the discharge system 5 along with the water flow.
remove.

In this embodiment, a strain gauge 80 is attached to the inner surface of the filter in order to measure the amount of deformation caused by the differential pressure between the inner and outer surfaces of the filter element in the foreign matter removing device 4. Even if the amount of water passing through the foreign matter removal device is constant, the pressure difference (differential pressure between the inside and outside) increases as foreign matter is captured in the filter element and the clogging rate increases. increase Due to this pressure difference, an external pressure difference is applied to the filter element, and the amount of deformation of the filter element increases or decreases depending on the magnitude of the difference. This amount of deformation is measured by a strain gauge, transmitted to a strain signal converter 83 through a lead wire 81, and then transmitted to a control device 60. The strain converter can also be built into the control device. In order to easily explain its characteristics, temporarily,
If we consider the filter element to be cylindrical, the external pressure ΔP
Stress σ(
Kp/mm2) is calculated as σ=-ΔP-d/200t...(1
) Here, d is the diameter of the cylinder (wn), and t is the thickness of the cylinder (rnm). The strain ε there is ε=σ/1 le...
(2) E is expressed as the Young's modulus (Kg/mm2) of the cylindrical material. (x), Equation (2) clearly shows that the external pressure ΔP acting on the cylinder and the strain ε on the cylinder surface are in a proportional relationship. Although we have explained here using the primary membrane stress in the elastic region of a simple cylindrical shape, such general relationships still apply locally even if the perforated plate has a conical cylindrical shape like a filter element. This holds true even if it is a deformation. Therefore, if the filter element traps foreign matter, clogging increases, and the pressure difference between the inside and outside increases, the deformation (strain) of the filter element surface increases as shown in FIG. This is measured using a strain gauge. The signal is sent to a control device 60 outside the foreign object removal device.
Here, it is compared with a specified value, and if it is above the specified value, the large mouth valve 20 is closed to the middle, a swirling vortex is generated to rip off the foreign matter from the filter surface, and the blowdown valve 30 is opened to remove the foreign matter from the discharge pipe. 13 to the discharge system.

According to the present invention, since the method measures the strain on the filter surface in the foreign matter removal device, the amount of foreign matter captured by the foreign matter removal device can be accurately detected without being affected by the dynamic pressure caused by the water flow inside the foreign matter removal device 4. If a foreign object exceeding a specified number is detected, a foreign object removal operation can be performed.

Further, since the signal is not accompanied by disturbance, even if the condenser heat load decreases, the flow rate decreases, and the determination differential pressure becomes small, detection and determination are possible without deterioration of accuracy.

Furthermore, by using a commonly used strain gauge, you only need to install one lead wire outlet for transmitting the signal, instead of installing two or a spare seat like in the past. This is unnecessary, since the inner surface of the foreign matter removing device 4 is generally lined with rubber to make it resistant to seawater, so reducing the number of seats has a large effect both in terms of man-hours and economically.

Alternatively, since the strain on the surface of the filter element, which is an important internal structure, can be monitored, interlocks to prevent damage can be established by setting specified values for the strength of the material.

In addition, since the foreign matter removal operation can be performed appropriately according to the present invention, the aforementioned power wastage due to the foreign matter removal operation and the deterioration of condenser performance due to water flow loss can be prevented.

Figures 5(a) and 5(b) show an example of application of the present invention, in which the amount of deformation of the filter element is detected by using a strain gauge and the amount of deformation of the reinforcing ring is changed to the rotation angle. Achieve by doing.

In addition to these embodiments, any method that measures the amount of foreign matter captured by detecting the amount of deformation of the filter element does not depend on the detection means.

In addition, in the figure, 3 is the outlet system, 11 is the artificial pipe, 12 is the outlet pipe,
13 is a discharge pipe, 15 is a filter intake side, 16 is a filter outlet side, 72 is a blade angle setting device, 73 is a blade angle detector, and 82 is a lead wire extraction seat.

According to the present invention, since it is possible to accurately detect the amount of foreign matter trapped in the foreign matter removal device, the frequency of unnecessary foreign matter removal operations can be reduced, thereby reducing wasted driving power and condensation due to water flow loss. This prevents the performance of the device from deteriorating. Furthermore, since the device is simplified, manufacturing and installation costs can be reduced.

[Brief explanation of drawings]

Figure 1 is a system diagram of a conventional foreign matter removal device, Figure 2 is a sectional view of the foreign matter removal device, Figure 3 is a relationship between the amount of cooling water and the differential pressure generated, and Figure 4 is a diagram of an embodiment of the present invention. FIG. 5 is a system diagram of a foreign matter removing device, and is a sectional view (a) of another embodiment of the present invention and a perspective view (b) of a reinforcing ring. 5L amount of water (≠)

Claims (1)

[Claims] 1. A foreign matter removal device with a built-in filter to prevent foreign matter from entering the condenser, and when foreign matter adheres to the filter, the foreign matter is removed by a swirling vortex generated by the inclination of the large mouth valve of the filter. In the foreign matter removing device that separates foreign matter from the surface of the filter and removes it from the casing, foreign matter is removed from the filter by detecting a change in distortion of the filter caused by a pressure difference between the inside and outside of the filter of the foreign matter removing device. A control device for a foreign matter removal device, characterized in that it detects adhesion and performs a foreign matter removal operation.