As one of the non-destructive testing methods to ensure the safe operation of equipment and improve the reliability of maintenance, industrial endoscopes have been widely used in the maintenance of boilers, steam turbines and generators in thermal power stations. There are three main types of products, namely Straight rigid mirrors, fiber optic endoscopes and video endoscopes. Video endoscopes are divided into two categories. One is a flexible portable digital video endoscope with a working length of 7 to 8 m. The probe uses a new technology such as electro-pneumatic guidance to control the direction of the probe. High resolution is used. A charge-coupled device (CCD) lens that achieves more than 500 lines of resolution and more than 45 times magnification; a quantitative measurement objective uses a shadow measurement system with three measurement modes: distance, oblique and depth, non-contact absolute measurement There is no need to provide a reference frame for the detected object, and it can be accurately calibrated by different positions of the shadow line projected by the probe onto the surface of the detected object, and directly measure the point-to-point, point-to-line distance and the between the two planes on the endoscopic image. Vertical depth (Figure 1) E1, 23. The other type is a video endoscopic crawler, as shown in Figure 2. The VCK video endoscopic crawler, which can work up to 150 m in length, can carry a direct-view lens, a rotating lens, an auxiliary luminaire and a recycling tool. The six-wheel drive makes it possible to move forward, backward, turn, climb and Crossing obstacles; clear images can be obtained with high-resolution CCD lenses; full-sealed pressure protection can be adapted to underwater inspections. VCK video endoscope and its associated mechanical recovery device are suitable for pipes, containers and equipment with inner diameter > sound 100 mm. Received date: 2005-04-08 Figure 1 Quantitative measurement of flexible probe video endoscope Figure 2 VCK video endoscopic The internal inspection and recovery of the mirror crawler is a six-wheel drive, full-rotation CCD lens for underwater inspection up to 10 m. Many years of on-site inspections show that VCK has reliable performance in the center hole of the turbine generator rotor, boiler header and pipeline of the thermal power plant and the busbar inspection of the substation, meeting the needs of maintenance. Moreover, the auxiliary equipment developed for on-site inspection has expanded its application range and improved its adaptability. Application of VCK endoscope in power system Turbine generator rotor center hole inspection Turbogenerator rotors are important rotating equipment for thermal power plants and are essential for the safe and continuous operation of thermal power plants. The center hole of the rotor is an inner hole that is 90 to 180 mm in diameter and penetrates the entire length of the rotor in order to eliminate forging defects during the manufacturing process. Due to the stress concentration on the inner wall of the rotor center hole, surface fatigue cracks may occur during long-term operation. Therefore, the detection of the inner wall of the rotor is an important means to ensure the safe operation of the turbine generator rotor. 1. Early endoscopy uses mostly straight rod and fiber optic endoscopes. The high-end side-view endoscope and the Welwyn VIDE02000 rotating straight-view side-view endoscope of the Hai Caikang Optical Instrument Factory pass through the front 45. The mirror can observe the condition of the inner wall of the rotor center hole; and the fiber endoscope can detect the inner wall of the rotor center hole through the curved portion of the front end of the lens. The VCK video endoscope currently used has the advantages of the above two devices, and has a wide field of view, a bright field of view, and a flexible and flexible crawler, which can realize multi-angle detection of any point on the inner wall of the rotor center hole, and obtain a stable and clear image. The minimum size of the VCK video endoscope crawler is åº100mm. In order to meet the detection of the center å‘L of the ping 90-98 mm, the auxiliary trolley is designed and manufactured, and the manual push rod can meet the needs of the direct-view lens and the rotating lens. . 1.2 boiler header inspection Boiler header is an important part of the boiler. It is subjected to high temperature and high pressure during operation. The internal components and the header itself and its connecting pipe are prone to cracks, which cause the parts to break and fall, and the joint box and the fillet weld of the pipe joint are cracked. Caused a serious accident. The inner diameter of the boiler header of the thermal power plant is 200-500mm, and the handcuffs L of the header have two forms: the end opening and the side opening. The inner diameter of the hand hole is 113 mm. The handcuffs of the header box are small. The endoscope crawler (table 100 mm) with the smallest diameter of the wheel can enter the inside of the header through the hand hole, but after entering the hand hole, the inner diameter of the header is large, and the height of the crawler is low. The field is limited, affecting the detection effect. To this end, the support device shown in Fig. 3 is designed, and when used for detecting a large diameter header, the CCD lens can obtain an ideal detection effect. From the analysis of the long-term field test results, it is found that in all the headers, the problem of the desuperheater header is most prominent. Due to the low temperature of the desuperheating water, the working temperature gradient of the relevant components is large, and the long-term work leads to thermal fatigue. In addition, due to the intermittent working mode and high pressure of the desuperheating water, the vibration of the desuperheating water pipe will generate vibration and aggravate the failure of the components. Once the desuperheating water nozzle and sleeve are damaged, it will further lead to the loss of the header of the joint box in Figure 3. On-site inspection has repeatedly found problems such as sleeve cracking, cracks in the inner wall of the header, cracking of the weld of the sleeve support, breakage of the spray pipe and failure of the nozzle. The step between the desuperheater sleeve and the header forms a step of 20 to 35 mm, and the endoscopic crawler often cannot climb the step. Therefore, the larger wheel is designed and manufactured, and the ability to climb the step of the crawler is improved. Climb up the 35 mm steps. Tests have shown that the above auxiliary devices broaden the application range of VCK devices. Taking the detection of the micro-spray desuperheater of the 1025t/h boiler reheater in a power plant as an example, in the overhaul, the three sets of desuperheating water nozzle parts of the reheater micro-spray desuperheater on both sides of the A and B were found to fall off. It is presumed that it falls into the desuperheater header and the high re-inlet header. The VCK video endoscope was used to check whether there were cracks on the inner wall, and three sets of sprinkler parts (nuts, gaskets and water sprinklers) were found and recovered by a video endoscope recovery device. Substation bus detection When the busbar of the SF6 gas insulated switch, the inlet and outlet bushings and the transformer busbar are faulty, due to the structural limitations of the equipment, the maintenance personnel cannot directly find the root cause of the problem, and the VCK video endoscope is used for the inlet and outlet bushings and transformers. The busbar inspection can find the discharge point conveniently, quickly and accurately, and determine the fault point, which greatly saves the maintenance period. Conclusion Many on-site inspections confirmed that the VCK video endoscope and its auxiliary devices played an important role in the inspection of power station boilers and steam turbine generator sets, and found and eliminated a large number of equipment defects to ensure the safe operation of the equipment. A3 Ribbed Manila Envelope,Skyline A3 Ribbed Envelope,Skyline A3 Ribbed Mailer,A3 Ribbed Brown Mailers Sun Kee Envelopes Limited , https://www.sunkeeenvelope.com