JPS62189596A - Steam leak alarm system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (a) Industrial application field The present invention is applicable to nuclear power plants and other steam utilization facilities.
This invention relates to a steam leak warning system that automatically warns of abnormal steam flailing.

Conventional technology Conventional steam leak monitoring systems are based on (i) a method in which judgment is made by using an ultra-RF sensor to detect ultrasonic waves generated by a vortex generated in the area when air leaks, or;
(ii) There is a method that monitors the electrical resistance of the electrostatic material and determines based on the change in electrical resistance that occurs when it absorbs moisture.

&→ Problems to be Solved by the Invention The problems to be solved by the present invention are as follows: (a) In the case of the ultrasonic method, the problems to be solved by the present invention are as follows: In addition to having to detect sound waves of a special wavelength from inside the ground, there are places where it is impossible to detect because it is an indirect phenomenon that relies on sound waves that are difficult to observe, and it is easy to generate false alarms.
(b) In the case of the electrical resistance method, the long-term operating temperature is as low as 75°C, and the resistance value changes with temperature. Because of this, it is extremely sensitive in high-temperature steam piping, etc., and n&! If you do it in a humid place, the atmosphere alone will cause steam leakage and will not function properly. I have a problem.

(c) Means for Solving the Problems The present invention, as a means for solving the above-mentioned problems, provides a ceramic humidity sensor and a temperature sensor that can be used in a wide range of temperatures, and directly attaches them to the heat insulating material at locations where steam leakage is expected. The humidity and temperature data of the area is converted into absolute humidity using a microcomputer, and the data is statistically processed to determine whether there is an abnormality or not, and an alarm is issued in the event of an abnormality. It attempts to provide a leak warning.

1;) Embodiment and Function The structure and function of an embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows the system configuration, which has a wide operating temperature range and consists of a ceramic humidity sensor 1 that converts relative humidity into electrical resistance, and a temperature sensor 2 that converts the relative humidity into electrical resistance corresponding to the temperature of the resistance thermometer. This constitutes the sensor section 10. The sensor unit 10 is directly embedded in a heat insulating material at a location where steam leakage is expected, and the analog signals of humidity and temperature sensed by the sensor unit 10 are amplified to an appropriate voltage using an amplifier 3 including a linearizer. , the amplified signal is converted into a 10-digit digital signal by an analog-to-diel converter 4, and the digital signal is transferred from one input port of a programmable peripheral interface 5 to a readable/writable memory via a data bus of a microcomputer 6. 8 as a 3-digit hexadecimal number, and a correspondence table between temperature and saturated vapor pressure is transferred from the read-only memory 7 to the read/write memory 8, and the value of the saturated vapor pressure divided by the temperature at that time is stored in the read/write memory 8. Calculate from that table,
The value is multiplied by the relative humidity to obtain the absolute humidity, and that value is also stored.The microcomputer 6 always calculates the water vapor content at that point from the humidity and temperature data taken in, and calculates the water vapor content within the time period. After calculating the average value, compare it with the previous data and the average data. If the current data has a water vapor content that is less than or equal to the previous data, the next collection will proceed as is, but if it is large, there is a steam leak. The program branches to a discrimination routine that discriminates.

Humidity and temperature data are always sampled at regular intervals, such as 200 ms, and the values are converted to hexadecimal form as described above and stored in memory alongside the previously sampled values. First, a comparison is made between the previous humidity He'' and the current humidity He.He'
- If He≧0, skip routine B. He
'-He (If 0, the difference is taken and compared with the value in the steam leak discrimination table. This discrimination table is stored in advance in the read/write memory 8 with the temperature Th and specified value E (Th) as shown in the attached table. If the difference is larger than E(Th) at a temperature below Th, it is assumed that there is a steam leak and an alarm is issued.If not, proceed to the next step.

The read/write memory 8 has a place for storing the average value of humidity, and always stores the average value Hem of the values measured so far. In the next step, this average value is compared with the current value. Here again, if Ham-He≧0, this routine is skipped. If Hem - He < 0, the difference is compared with the judgment table, but this time, the value E (Th) of the judgment table is not the local value, but E = 1 in hexadecimal.
The value of the difference is compared with 00H-E(Th), and if the difference is greater than E, it is assumed that there is a steam leak and an alarm is issued. If it is small, remove it from this routine.

The reason why the judgment is performed in two stages is based on the assumption that there are two types of steam leaks: one in which a large amount of steam leaks suddenly, and one in which steam leaks slowly and gradually. A flowchart of this routine is shown in FIG.

In the steam leak detection routine, if it is determined that there is no steam leak, the data collection action is resumed, but if a steam leak is determined, a steam leak alarm signal is sent to the output port of the programmable peripheral interface 5, In response to this signal generation u9, a display panel 120 and an alarm lamp 13 corresponding to the location where the sensor unit is placed.
will flash and the buzzer 14 will sound.

A unit composed of the amplifier 3 to signal generator 9 is referred to as a transmitter section 11, and a transmitter section of a unit corresponding to the installation location of each sensor section is configured, and each transmitter section is connected to a display panel 12. The sensors connected to the sensor constitute the entire system, and the display panel 12 displays alarm lamps 13 indicating the locations where each sensor section is installed and an alarm. A buzzer 14 is attached.

(F) Effects of the Invention As explained above, the present invention uses a ceramic humidity sensor that can be used at high temperatures, and by placing it near a place where there is a risk of steam leakage, the sensitivity and accuracy can be increased, resulting in false alarms. In addition, since a temperature sensor is combined with a humidity sensor and a computer constantly calculates absolute humidity, it is not affected by changes in relative humidity caused by temperature fluctuations, and is not affected by fluctuations in steam usage or temperature fluctuations. It operates stably without issuing false alarms due to changes in the atmosphere, and since it uses a microcomputer to keep track of humidity statistics over a long period of time, it does not know what the normal humidity value is. Since it is possible to judge whether the normal state is abnormal or not, it can be used even if the VJ state is in a high temperature and high humidity atmosphere1.
I can do things! Because it converts humidity and temperature analog signals into digital signals on the spot and performs subsequent processing, it is less affected by external noise, and there is no need to worry about false alarms caused by noise (also, there is no need to worry about false alarms caused by noise). Not only is it resistant to voltage fluctuations, making it suitable for on-site systems, but the transmitter section is entirely integrated into a unit, and there are no sliding or consumable parts, so it can be maintained over a long period of time.

Separate table Steam leak determination table

[Brief explanation of drawings]

Figure 1 is a system diagram showing the configuration of one embodiment of the present invention;
The figure is a flowchart of the same steam leakage discrimination routine.

Claims (1)

[Claims] A ceramic humidity sensor and a temperature sensor are directly embedded in the insulation material at locations where steam leaks are expected, and the humidity and temperature data at those locations is converted to absolute humidity using a microcomputer, which is then subjected to statistical processing. This steam leak alarm system is characterized by determining the presence or absence of an abnormality based on the object, and issuing an alarm in the event of an abnormality.