Analysis of steam turbine cylinder deformation measurement technology
Abstract: The thermal efficiency of steam turbine units in large-scale thermal power plants (especially the thermal efficiency of individual cylinders) is decisive for the safe production, economic operation, and safe and civilized production of the units, which is directly related to the economic benefits of the power plants and the safe operation of the units. In this regard, each power plant pays particular attention to the overhaul of the unit, and has high requirements for quality control of turbine overhaul, especially in the adjustment of the clearance of the through-steam part of the turbine overhaul to be more cautious, and the good or bad adjustment of the through-steam clearance determines the quality of the overhaul, and improves the operation efficiency.
Keywords: steam turbine; deformation volume measurement technology; puddle deformation
Due to structural reasons, manufacturing reasons, and thermal stresses, there exists a great deal of deformation of the cylinder after the unit is operated, and when the unit is overhauled, the deformation volume should be measured and analyzed firstly, and the reasons for the steam seal touching should be judged according to the analysis results, so that the gap can be narrowed and corrected during the overhaul. Puddle deformation amount technology is through the accumulation of a large number of whole machine modification work experience, we note that the domestic unit generally have cylinder deformation and diaphragm deformation, which leads to the unit full-cylinder and half-cylinder state of the diaphragm puddle center is different, which not only affects the efficiency of the unit overhaul when the steam seal gap adjustment work, but also affects the operation of the diaphragm static vane grille and the rotor moving vane grille of the concentricity, affecting the flow of steam, reduce the unit This affects steam flow and reduces the thermal efficiency of the unit. In view of this situation, we have developed a diaphragm puddle deformation measuring instrument, which has been successfully utilized in hundreds of power plants and achieved remarkable results. Measurement of the half-cylinder state relative to the full cylinder puddle change is the most critical part of our real adjustment of the steam seal gap, real mastery of the amount of deformation, in order to optimize the adjustment of the steam seal gap. Measurement of high-pressure inlet steam balance ring sleeve disintegration pits, sleeve ellipticity, and then measure the installation of the steam seal after the steam seal ellipticity, combined with the last overhaul of the gap standard, to determine the rotor in the operation of the largest elliptic trajectory, is the largest deflection in the end in accordance with the maximum deflection in accordance with how much the gap installation and optimization of the basis of the steam seal gap.
1 puddle deformation measurement
The work is generally carried out after the buckle empty cylinder to measure the bonding surface clearance, if the bonding surface exists a large opening, need to be repaired, it is necessary to measure the puddle deformation after the repair. In the overhaul unit, after the center of the full solid cylinder is qualified, the center of the stationary part should be statically corrected. This includes the static centering of the holding ring, spacer sleeve, spacer plate, shaft seal sleeve and other parts. Generally it is the lower half real cylinder dynamic and static center shall prevail. In fact, the deformation of high and medium pressure and low pressure cylinders is very large, in general, the dynamic and static puddle center of the lower half of the cylinder and the dynamic and static puddle center of the full cylinder is very large, without considering the dynamic and static concentricity of the full cylinder, often after overhaul of the unit start-up there is a dynamic and static friction sound, the start-up of the unit to the full speed does not go smoothly, and so the friction sound is small, the unit is also to the full speed, the efficiency of the load carrying efficiency (heat consumption, steam consumption, coal consumption) The efficiency with load (heat consumption, steam consumption, coal consumption) did not improve. In order to improve efficiency, think:
1) false shaft to the rotor center after the qualified oil block puddle shall prevail, find the center of the lower half of the real cylinder dynamic and static center and record, including the holding ring, the spacer sleeve, the spacer, the shaft sealing sleeve and so on. Then start to measure out the dynamic and static center of the lower half of the real cylinder (holding ring, spacer sleeve, spacer, shaft seal sleeve, etc.) and record. There is a difference between the center of the dynamic and static puddle under the full solid cylinder and the center of the dynamic and static puddle under the half solid cylinder. In the overhaul process, the actual dynamic and static puddle centers under the full cylinder should be corrected to the dynamic and static puddle centers under the half cylinder. Then adjust the steam seal gap on the full solid cylinder, after the steam seal gap is adjusted and qualified, the start-up will be smooth, there is no static or dynamic friction sound, and the efficiency with load will be greatly improved (turbine installation and overhaul), which is actually the process of adjusting the static and dynamic centers under the full solid cylinder. Especially the unit that has been run. Equipment metal materials after a long time stress failure, has been finalized.
2) High-medium and low-pressure cylinders are not adjustable, so the overhaul of the unit should be more realistic consideration of the dynamic and static center of the full solid cylinder.
2 Puddle Deformation Gauge Probe Arrangement
The measurement should be marked on each puddle's measurement point (measuring 3 points, i.e., left a, right b, and lower c) before measurement, so that the measurement can be made at the same position every time to improve the accuracy of the measurement. Snap on the half-holding ring spacer and inner cylinder and retest the cylinder plane clearance in its natural state. If it is the first overhaul, it is recommended to measure the center of each part of the pits again in this state before tightening the bolts, (still measuring the next three points) We all know that in the half-cylinder state, the cylinder's stiffness is lower than the full cylinder. Especially the combined cylinder machine its stiffness is poor, in the upper half of the holding ring, the inner cylinder lifted into, in its upper half of the weight of the parts, the cylinder will be deformed downward. This figure should be a measurement, the measurement results for future overhaul has been able to draw on. According to the distribution of plane clearance tight 1/3 bolts, bolts tightened after the flange plane of the maximum clearance should be less than 0.05mm. such as clearance exceeds the standard should tighten all the bolts; such as tightening all the bolts after the clearance is still exceeding the standard hot tighten the bolts, until the flange plane of the maximum clearance should be less than 0.05mm. (Individual edges of the tightening can not be removed exceptions.) Measurement of the holding ring, the inner cylinder in the tightening of the bolts after the center of the pits. When measuring the inner cylinder, we require the measurement technique as well as the measurement requirements to be completely consistent with the measurement of the outer cylinder. Once we have fastened the inner and outer cylinders, we measure the center of the puddle through the upper measuring point, lower measuring point, left measuring point, and right measuring point. During this measurement, we have to analyze the change in the center of the inner and outer cylinders according to their measurements. Usually, the center change of the inner cylinder and outer cylinder is caused by the problem of the opening flange and the bolt fastener. Therefore, we have to check the stiffness and perpendicularity of the bolt fasteners, because once the bolt fasteners have strength and perpendicularity problems, it will affect the pivot elevation of the inner cylinder and the outer cylinder. Through this measurement of the cylinder block, we can analyze from the measurement results that the true center between the inner and outer rings of the cylinder as well as the spacer plate is the true center of the pivot. Same as the previous measurement operation, we also need to fasten the outer cylinder during the measurement process, but we can not connect the bolts and flanges in this process, so that we can hold the center of the ring and the center of the inner cylinder through the gravity of the outer cylinder itself for the measurement of the center of the inner cylinder changes. After the cylinder is opened, we have to review the center of the various changes in data, and then through the review of the results with the last measurement data for comparison, if the two measurements do not change much, we believe that the deformation of the cylinder is more stable, if the two measurements of the data changes are large, it means that the center of the cylinder changes are large, we need to analyze the change, to find out the reasons for the center of the change to ensure that the measurement results are reliable. We need to analyze this change and find out the reason for the change of the center to ensure that the measurement results are reliable. Compare the measurement results and calculate the amount of change in the center of each steam seal after tightening the cylinder bolts. In the open cylinder state, adjust the centers of the holding ring and spacer pits according to the actual deviation and the amount of change, so that they are in the concentric position with the rotor after the cylinder is closed. That is, to ensure that the depression left is equal to right and up is equal to down in the full solid cylinder state.
Taking into account the actual situation of the site, some of the through-flow part of the inner diameter is small, in most cases, the upper half of the holding ring, the inner cylinder buckle, people can not enter, after closing the outer cylinder can only be measured at the next 3 points. Therefore, it is also necessary to measure the ellipticity of each holding ring and inner cylinder in the natural state and after tightening the flange bolts, and incorporate this part of the effect when calculating the amount of change in the center of each steam seal puddle after tightening the cylinder bolts. Through accurate deformation measurement, it can better grasp the actual change of cylinder half-cylinder and full solid cylinder, and can more accurately grasp the value of the steam seal adjustment gap to ensure that the adjusted steam seal gap is more real and reliable, so as to achieve the optimized adjustment of the steam seal gap. In the process of steam turbine application, the application efficiency has a great impact on the whole unit, which is directly related to the normal operation of the unit and the economic benefits generated. It is for this reason that in the process of normal operation of the unit, we should carry out a comprehensive inspection of the steam turbine, especially the cylinder deformation problem should be given high importance. In the process of cylinder deformation detection, we have to focus on the cylinder gap inspection, only then can effectively check the use of the cylinder effect and cylinder performance indicators, in order to effectively reduce the cylinder inspection process brought about by the huge workload, we are in the normal inspection, we have to try to adjust the radial clearance of the cylinder, to ensure that the cylinder gap to meet the application standards.
3 Conclusion
Through the application of this technology, the steam seal gap adjustment and the scraping technology of the vapor barrier with the cylinder repair in the overhaul provides the basic data, so as to optimize the turbine flow gap to achieve the ultimate goal of improving the turbine cylinder efficiency and thermal efficiency of the unit to provide a strong technical guarantee to reduce the coal consumption of the unit, and power plant power generation costs can be reliably reduced. The optimization of turbine flux gap provides a practical solution to improve the cylinder efficiency and thermal efficiency of the turbine, thus reducing the coal consumption of the unit and reliably lowering the cost of power generation.
References
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[2]National Economic and Trade Commission.DL/T753-2001, Turbine Cast Steel Patch Welding Technical Conditions [S]. Beijing: China Electric Power Press, 2001.
[3] National Energy Administration. DL/T819-2010, Thermal Power Plant Welding Heat Treatment Technical Regulations [S]. Beijing: China Electric Power Press, 2010.
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