Marine pipeline acoustic emission monitoring system and monitoring methodTechnical Field
The invention belongs to the technical field of nuclear power device leakage detection, and particularly relates to a marine pipeline acoustic emission monitoring system and a marine pipeline acoustic emission monitoring method.
Background
The nuclear power system and the high-energy pipelines such as steam, cooling water and the like of the two loops are compact in arrangement, small in space and the like, so that the difficulty of overhauling and maintaining is high in service, and the equipment and personnel safety of the whole ship are seriously endangered by pipeline breakage, leakage and even fracture accidents.
The pipeline leakage detection method commonly used in the current land nuclear power station comprises the following steps: pit liquid level monitoring, air particle monitoring, flow monitoring and the like can be detected after pipeline breakage is formed, and hysteresis exists. In recent years, LBB (Pre-breaking leakage, leak Before Break) technology is generally used as a future development trend in the nuclear power field at home and abroad. The basic idea is that when the pipeline is leaked early, the early warning is realized before the pipeline is broken by measuring and identifying through the monitoring device, and the safe shutdown is realized with plenty of time so as to avoid the occurrence of the double-end breakage of the pipeline.
The pit liquid level monitoring is to collect leakage steam after condensation into a floor drain, send the leakage steam to a containment pit through a floor drain transmission pipeline for final collection, and calculate the pipeline leakage rate through a liquid level meter arranged in the pit. Air particle monitoring is to measure the content of a certain pipe medium in the air, and if the concentration is significantly higher than the normal value, the pipe is considered to leak. The flow monitoring is to judge the leakage of the pipeline according to the transient change of the flow caused by the leakage of the pipeline. The measuring methods are long in time, can not be detected after the pipeline is damaged, cannot timely reflect the leakage of the pipeline, and are difficult to position the leakage position of the main steam pipeline.
Therefore, it is necessary to design a monitoring system capable of early warning and fast positioning before the pipeline is damaged and leaked, and by monitoring the pipeline state in service, online and real time, the high-energy pipeline damage accident and the serious consequences attached to the high-energy pipeline damage accident are avoided, and the safety and the reliability of the nuclear power system are improved.
Disclosure of Invention
The invention aims to solve the technical problems that: the marine pipeline acoustic emission monitoring system and the marine pipeline acoustic emission monitoring method are used for early warning and rapid positioning before damage and leakage of the pipeline occur.
The technical scheme adopted by the invention for solving the technical problems is as follows: the marine pipeline acoustic emission monitoring system comprises an acoustic emission sensor, an acoustic emission signal amplifier, a signal acquisition card and a signal processing terminal which are sequentially connected; the acoustic emission sensor is arranged on the pipeline to be detected and is used for detecting signals, and the acoustic emission sensor is used for converting mechanical vibration signals generated on the surface of an object to be detected by an acoustic emission source into electrical signals by receiving acoustic emission signals generated in the material or the structure and transmitting the electrical signals to the acoustic emission signal amplifier; the acoustic emission signal amplifier is used for pre-amplifying signals; the signal acquisition card is used for acquiring and storing signals; the signal processing terminal is used for processing, analyzing and displaying signals.
According to the scheme, the acoustic emission sensor measuring points are arranged at weak links of the pipeline to be measured and are used for receiving acoustic emission signals generated when cracks appear in the pipeline.
According to the scheme, the acoustic emission sensor is arranged in the heat insulation layer of the outer wall surface of the pipeline.
According to the scheme, the signal processing terminal is arranged in the monitoring cabinet in the control room and is used for facilitating an operator to remotely and online monitor the pipeline to be monitored in the inconvenient space.
A monitoring method based on a marine pipeline acoustic emission monitoring system comprises the following steps:
s1: an acoustic emission sensor on a pipeline to be tested detects an acoustic emission signal generated when the surface of the pipeline is cracked, converts the acoustic emission signal into an electric signal and sends the electric signal to an acoustic emission signal amplifier;
s2: the acoustic emission signal amplifier preamplifies the received signal and sends the signal to the signal acquisition card;
s3: the signal acquisition card acquires and stores the received signals and sends the signals to the signal processing terminal;
s4: the signal processing terminal is used for processing and analyzing the received signals and displaying the signals to an operator.
Further, in the step S4, the signal processing terminal identifies the characteristic signal in the received signal by the characteristic comparison method, which specifically includes the steps of:
s41: separating noise by filtering;
s42: identifying abnormal signals and performing leakage early warning by comparing the characteristics including amplitude and peak frequency; let U0 be the measured value of acoustic emission signal at 0 m, c be the pipeline attenuation coefficient, locate fault point based on signal attenuation principle, measured value U of acoustic emission signal at L mL The method comprises the following steps:
UL ＝U0 ×e-cL 。
a computer storage medium having stored therein a computer program executable by a computer processor, the computer program performing a monitoring method.
The beneficial effects of the invention are as follows:
1. according to the marine pipeline acoustic emission monitoring system and the marine pipeline acoustic emission monitoring method, active monitoring is carried out on the main steam pipeline in the reactor cabin in an on-line and real-time mode, the early warning and rapid positioning functions before the pipeline is damaged and leaked are achieved, the accident probability of a nuclear power system is greatly reduced, the high-energy pipeline damage accident and the serious consequences attached to the high-energy pipeline damage accident are avoided, and the safety and reliability of the nuclear power system are improved.
2. The acoustic emission sensor is adopted to identify the leakage and damage risks of the pipeline in the stage of surface crack occurrence of the pipeline, and early warning is carried out; and more abundant reaction and decision time are provided for command and operators, so that the rationality of decision making and the accuracy of operation are improved.
3. According to the invention, the acoustic emission signals of the pipeline are acquired and processed through the signal acquisition card and the signal processing terminal, so that the important high-energy pipeline of the nuclear power system is provided with a real-time online active monitoring mechanism, on one hand, the hysteresis of information transmission is reduced, and on the other hand, the harsh environments that patrol personnel enter a narrow space, have a radioactive limiting area and the like are avoided.
4. The invention realizes the accurate positioning of the leakage point based on the attenuation phenomenon of the acoustic emission signal transmitted in the medium, and adopts corresponding measures such as emergency maintenance, fault system isolation or emergency shutdown and the like to the damaged pipeline as soon as possible according to the leakage position and the navigation condition.
Drawings
Fig. 1 is a functional block diagram of an embodiment of the present invention.
Detailed Description
The invention will be described in further detail with reference to the drawings and the detailed description.
Referring to fig. 1, an embodiment of the invention comprises an acoustic emission sensor, an acoustic emission signal amplifier, a signal acquisition card and a signal processing terminal; the method can be divided into four links of signal detection, pre-amplification, signal acquisition and storage, and signal processing analysis and display.
The signal detection adopts an acoustic emission sensor as a signal detector, and a series of acoustic emission signals generated inside a material or a structure are received through a plurality of sensors arranged on a pipeline, so that stress waves (mechanical vibration signals) generated on the surface of an object to be detected by an acoustic emission source are converted into electric signals. And arranging the measuring points of the acoustic emission sensor at the weak links of the pipeline, and receiving acoustic emission signals generated when the pipeline is cracked.
The acoustic emission monitoring system is applied to a main steam pipeline of the ship nuclear power system. The acoustic emission sensor is arranged in the heat insulation layer of the outer wall surface of the main steam pipeline through the waveguide rod, and detected pipeline acoustic emission signals enter the monitoring cabinet for filtering and analysis after signal amplification. The monitoring cabinet is located in the control room, can conduct remote on-line monitoring on the main pipeline arranged in the reactor cabin, and can prevent inspection personnel from entering a narrow space and being in the cabin with radioactivity.
The signal processing analysis identifies the characteristic signal by means of a characteristic comparison. The acoustic emission signals are subject to interference of various background noises, such as mechanical noise, friction noise, environmental noise, electromagnetic noise and the like, and the noise signals and the acoustic emission signals are mutually overlapped to form a sampling signal of the sensor. Firstly, noise separation is carried out through filtering, and then, abnormal signals are identified through comparing characteristics such as amplitude, peak frequency and the like, and leakage early warning is carried out. And the fault point positioning is realized based on the signal attenuation principle, and the following formula is shown.
UL ＝U0× e-cL ；
Wherein:
UL -sound emission at L meterA radio signal actual measurement value;
U0 -measuring an acoustic emission signal at 0 m;
c-the pipe attenuation coefficient.
The above embodiments are merely for illustrating the design concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, the scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications according to the principles and design ideas of the present invention are within the scope of the present invention.