Rapid cooling system for large bolt of steam turbine and operation method

Abstract

The invention discloses a rapid cooling system for a large bolt of a steam turbine and an operation method, the large bolt comprises a double-thread screw with a through hole and a nut matched with the screw, the double-thread screw is in clearance fit with a flange bolt hole, and the rapid cooling system comprises a pipeline system and a cooling medium storage device; the pipeline system comprises a main pipeline, a first branch and a second branch, wherein the first branch and the second branch are used for cooling the interior and the exterior of the large bolt. One end of the main pipeline is connected with the cooling medium storage device, and the other end is connected with the first branch and the second branch in parallel; one end of the first branch is connected with the main pipeline, and the other end of the first branch is smaller than the through hole of the double-thread screw in diameter and arranged in the through hole; a medium input through hole and a medium discharge through hole which are communicated with the flange bolt hole are formed in one side of a cylinder of the steam turbine; one end of the second branch is connected with the main pipeline, and the other end is connected with the medium input through hole. The bolt can be rapidly cooled, the bolt cooling time is shortened, and the hot tightening efficiency and the working efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbines, and specifically to a rapid cooling system and operation method for large bolts of steam turbines. Background Art

[0002] For high-temperature and high-pressure components such as the steam turbine cylinder, the large bolts 4 used are generally thermally tightened to ensure sufficient pre-tightening force on the joint surface, thereby ensuring the airtightness of the unit and preventing high-pressure steam leakage. As Figure 1 — Figure 3 shown, the steam turbine includes a cylinder upper half 1 and a cylinder lower half 2 which are symmetrically arranged up and down. There are interconnected flange bolt holes 3 in the cylinder upper half 1 and the cylinder lower half 2; the large bolt 4 includes a double-headed screw 41 having a through hole 411 and a nut 42 that mates with the screw. The through hole 411 runs through the upper and lower ends of the double-headed screw 41. The double-headed screw 41 is arranged in the flange bolt hole 3 and has a clearance fit with the flange bolt hole 3; the upper and lower ends of the double-headed screw 41 respectively extend out of the flange bolt hole 3 and are threadedly connected to the nut 42.

[0003] The commonly used thermal tightening method is to heat the bolt using an electric heating device and twist the nut 42 as required to perform thermal tightening on the bolt. After cooling, the bolt elongation is measured, and the required pre-tightening force of the bolt is ensured according to the bolt elongation. This method is widely used for the tightening of high-temperature bolts of steam turbines, but this method has the problem of low efficiency. Specifically, each thermal tightening process of the large bolt 4 takes about 4 hours, and the natural cooling process takes about 40 hours. If the measured bolt elongation does not meet the requirements, the bolt needs to be thermally tightened again according to the above steps based on the deviation value of the bolt elongation. The bolt thermal tightening generally needs to be operated 2-3 times according to the above steps, and it generally takes 4-6 days to complete the thermal tightening of the bolts of a single cylinder.

[0004] At the same time, in recent years, due to the tight maintenance cycle of the unit, the requirements for bolt thermal tightening work cannot be met, resulting in the lack of measurement of bolt elongation, and thus the occurrence of problems such as insufficient bolt tightening force and steam leakage in some unit cylinders. Summary of the Invention

[0005] The purpose of the present invention is to provide a rapid cooling system and operation method for large bolts of steam turbines that can rapidly cool the bolts, thereby improving the thermal tightening efficiency and work efficiency, in view of the deficiencies of the prior art.

[0006] The technical objectives of the present invention are achieved through the following technical solutions: A rapid cooling system for large bolts of a steam turbine. The steam turbine includes an upper half of a cylinder and a lower half of a cylinder which are symmetrically arranged up and down. There are communicating flange bolt holes in the upper half of the cylinder and the lower half of the cylinder. The large bolt includes a double-headed screw with a through hole and a nut that mates with the screw. The double-headed screw has a clearance fit with the flange bolt hole. The rapid cooling system includes a pipeline system and a cooling medium storage device. The pipeline system includes a main pipeline, a first branch for cooling the inside and outside of the large bolt, and a second branch. One end of the main pipeline is connected to the cooling medium storage device, and the other end is in parallel with the first branch and the second branch. One end of the first branch is connected to the main pipeline, and the other end has a diameter smaller than the through hole of the double-headed screw and is arranged in the through hole. On one side of the cylinder of the steam turbine, there are a medium input through hole and a medium discharge through hole that communicate with the flange bolt hole. One end of the second branch is connected to the main pipeline, and the other end is connected to the medium input through hole.

[0007] Preferably, the first branch includes a first upper branch and a first lower branch which are symmetrically arranged up and down. A medium input pipeline that has a clearance fit with the through hole is arranged in the through hole of the double-headed screw. Medium discharge holes for outputting the medium are arranged on the pipe body of the medium input pipe. Both ends of the medium input pipe extend out of both ends of the through hole and are detachably and fixedly connected to the first upper branch medium output end and the first lower branch medium output end of the first upper branch and the first lower branch respectively.

[0008] Preferably, the medium discharge holes are arranged in the middle of the medium input pipe.

[0009] Preferably, fixing covers that cover the nuts are connected to both ends of the medium input pipe. The fixing covers are detachably and fixedly connected to the medium input pipe. Medium discharge holes are arranged around the circumference of the cover body of the fixing covers.

[0010] Preferably, the medium input through hole includes an upper side medium input through hole and a lower side medium input through hole that are symmetrically arranged on the upper half of the cylinder and the lower half of the cylinder. The upper side medium input through hole and the lower side medium input through hole are respectively arranged at the lower part of the upper half of the cylinder and the upper part of the lower half of the cylinder. Correspondingly, the second branch includes a second upper branch and a second lower branch that are arranged in parallel. The medium discharge through hole includes an upper side medium discharge through hole and a lower side medium discharge through hole that are symmetrically arranged on the upper half of the cylinder and the lower half of the cylinder. The upper side medium discharge through hole and the lower side medium discharge through hole are respectively arranged at the upper part of the upper half of the cylinder and the lower part of the upper half of the cylinder.

[0011] Preferably, the upper side medium input through hole and the lower side medium input through hole are multiple and arranged longitudinally. Correspondingly, the second upper branch and the second lower branch connected to the upper side medium input through hole and the lower side medium input through hole are multiple pipelines arranged in parallel. The number of the upper side medium discharge through hole and the lower side medium discharge through hole arranged longitudinally is the same as that of the upper side medium input through hole and the lower side medium input through hole.

[0012] Preferably, the number of the upper and lower medium discharge through - holes arranged vertically is greater than or equal to three times the number of the upper and lower medium input through - holes arranged vertically.

[0013] Preferably, the cooling medium in the cooling medium storage device is compressed air.

[0014] An operation method of the above - mentioned quick cooling system for large bolts of a steam turbine includes the following steps: Step 1: During the cooling process, regularly measure the surface temperature of the large bolt through an infrared thermometer; Step 2: Select the appropriate opening degree of the flow regulating valve according to the measured temperature of the large bolt to control the flow rate of the cooling medium; when the temperature of the large bolt is higher, the opening degree of the flow regulating valve is smaller; when the temperature of the large bolt is lower, the opening degree of the flow regulating valve is larger.

[0015] Preferably, the specific steps of Step 2 are as follows: Step 2.1: When the temperature of the large bolt is higher than 200 °C Keep the opening degrees of the flow regulating valves on the first branch and the second branch at 4 - 7%; Step 2.2: When the temperature of the large bolt is between 150 - 200 °C Keep the opening degrees of the flow regulating valves on the first branch and the second branch at 13 - 17%; Step 2.3: When the temperature of the large bolt is between 100 - 150 °C Keep the opening degrees of the flow regulating valves on the first branch and the second branch at 28 - 32%; Step 2.4: When the temperature of the large bolt is lower than 100 °C Keep the opening degrees of the flow regulating valves on the first branch and the second branch at 100%; Step 2.5: When the temperature of the large bolt reaches the local air temperature Keep the opening degrees of the flow regulating valves on the first branch and the second branch at 100% and maintain for 13 - 20 minutes, then stop cooling.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention cools and reduces the temperature of the large bolt synchronously from the inner and outer walls of the large bolt through the cooling medium, and no large thermal stress will be generated; the cooling medium contacts and exchanges heat evenly with the inner and outer surfaces of the bolt, and no large thermal stress will be generated. The present invention can quickly cool the bolt, reduce the cooling time of the bolt to improve the thermal tightening efficiency; the entire cylinder thermal tightening and measurement work can be compressed to be completed within one day, which can effectively improve the work efficiency.

[0017] 2. The first branch of the present invention includes a first upper branch and a first lower branch which are symmetrically arranged up and down; a medium input pipe which is in clearance fit with the through hole is arranged in the through hole of the double-headed screw; a medium output hole for outputting the medium is arranged on the pipe body of the medium input pipe; both ends of the medium input pipe extend out of both ends of the through hole and are detachably and fixedly connected to the first upper branch medium output end and the first lower branch medium output end of the first upper branch and the first lower branch respectively. By adopting this technical measure, the working efficiency and the applicable range can be improved.

[0018] 3. The medium output hole of the present invention is arranged in the middle of the medium input pipe. By adopting this technical measure, the cooling medium moves from the middle of the through hole of the double-headed screw to the upper and lower ends of the through hole, achieving uniform contact heat exchange and not generating large thermal stress.

[0019] 4. The operation method of the rapid cooling system for the large bolts of the steam turbine of the present invention is simple to operate. By adopting a step-by-step cooling method, the temperature of the large bolts can be decreased evenly, and the thermal stress of the large bolts is small. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is Figure 1 the schematic structural diagram of the middle cylinder, the large bolt, the medium input pipe and the fixing cover; Figure 3 is a partial right-side view of the cylinder; Figure 4 is a schematic structural diagram of a kind of medium input pipe of the present invention; Reference Numerals: 1 - upper half of the cylinder; 11 - upper-side medium input through hole; 12 - upper-side medium discharge through hole; 2 - lower half of the cylinder; 21 - lower-side medium input through hole; 22 - lower-side medium discharge through hole; 3 - flange bolt hole; 4 - large bolt; 41 - double-headed screw; 411 - through hole; 42 - nut; 5 - main pipeline; 6 - first branch; 61 - first upper branch; 62 - first lower branch; 7 - second branch; 71 - second upper branch; 72 - second lower branch; 8 - medium input pipe; 81 - medium output hole; 801 - upper-side medium input pipe; 8011 - upper-side medium output hole; 802 - lower-side medium input pipe; 8021 - lower-side medium output hole; 803 - plug; 9 - fixing cover; 91 - medium discharge hole; 92 - ferrule joint; 10 - cooling medium storage device. Detailed Embodiments

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention usually described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0023] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0024] Embodiment 1 As Figure 1 — Figure 3 shown, a rapid cooling system for large bolts of a steam turbine, the steam turbine includes an upper half cylinder 1 and a lower half cylinder 2 symmetrically arranged up and down, and there are communicating flange bolt holes 3 in the upper half cylinder 1 and the lower half cylinder 2; the large bolt 4 includes a double-headed screw 41 having a through hole 411 and a nut 42 mating with the screw, and there is a clearance fit between the double-headed screw 41 and the flange bolt hole 3. The rapid cooling system includes a pipeline system and a cooling medium storage device 10; the pipeline system includes a main pipeline 5, a first branch 6 and a second branch 7 for cooling the inside and outside of the large bolt 4; one end of the main pipeline 5 is connected to the cooling medium storage device 10, and the other end is connected in parallel with the first branch 6 and the second branch 7; one end of the first branch 6 is connected to the main pipeline 5, and the other end has a diameter smaller than the through hole 411 of the double-headed screw 41 and is arranged in the through hole 411; on one side of the cylinder of the steam turbine, there are a medium input through hole and a medium discharge through hole communicating with the flange bolt hole 3; one end of the second branch 7 is connected to the main pipeline 5, and the other end is connected to the medium input through hole. The medium input through hole and the medium discharge through hole on one side of the cylinder do not affect the strength and stiffness of the original cylinder. The cooling medium cools and reduces the temperature synchronously from the inner and outer walls of the large bolt 4, and no large thermal stress will be generated; the cooling medium makes uniform contact heat transfer with the bolt surface, and no large thermal stress will be generated. By adopting this technical measure, the bolt can be rapidly cooled, the cooling time of the bolt can be reduced to improve the thermal tightening efficiency; the entire cylinder thermal tightening and measurement work can be compressed to be completed within one day, which can effectively improve the work efficiency.

[0025] Specifically, the pipeline system includes a main pipeline 5, a first branch 6 and a second branch 7 for cooling the inside and outside of the large bolt 4. Among them, the main pipeline medium input end of the main pipeline 5 is connected to the cooling medium storage device 10, and the main pipeline medium output end of the main pipeline 5 is connected in parallel with the first branch 6 and the second branch 7. A stop valve is provided on the main pipeline 5. The first branch pipeline medium input end of the first branch 6 is connected to the main pipeline medium output end of the main pipeline 5, and the diameter of the first branch pipeline medium output end of the first branch 6 is smaller than the through hole 411 of the double-headed screw 41 and is arranged in the through hole 411. Cooling medium is output into the through hole 411 of the double-headed screw 41 of the large bolt 4 through the first branch 6, and after participating in the cooling, the cooling medium is discharged outward from the upper and lower ends of the through hole 411, so as to cool the inner wall of the double-headed screw 41.

[0026] As Figure 1 — Figure 3 shown, a medium input through hole and a medium discharge through hole communicating with the flange bolt hole 3 are provided on the right side of the cylinder of the steam turbine; the second branch pipeline medium input end of the second branch 7 is connected to the main pipeline medium output end of the main pipeline 5, and the second branch pipeline medium output end of the second branch 7 is connected to the medium input through hole. In actual use, the second branch pipeline medium output end is threadedly connected to the medium input through hole. An internal thread is provided at the connection between the medium input through hole and the second branch pipeline medium output end, and an external thread is provided at the second branch pipeline medium output end. Cooling medium is input into the flange bolt hole 3 through the second branch 7 and the medium input through hole to cool the outer wall of the double-headed screw 41, and the cooling medium that has participated in the cooling is discharged through the medium discharge through hole, so as to realize the cooling of the outer wall of the double-headed screw 41. As Figure 1 、 Figure 2As shown in the figure, the first branch 6 includes a first upper branch 61 and a first lower branch 62 which are symmetrically arranged up and down; a medium input pipe 8 which is in clearance fit with the through hole 411 is arranged in the through hole 411 of the double-headed screw 41; a medium output hole 81 for outputting the medium is arranged on the pipe body of the medium input pipe 8; both ends of the medium input pipe 8 extend out of both ends of the through hole 411 and are detachably and fixedly connected to the first upper branch medium output end and the first lower branch medium output end of the first upper branch 61 and the first lower branch 62 respectively. During actual use, flow regulating valves are respectively arranged on the first upper branch 61 and the first lower branch 62. The first branch 6 adopts the first upper branch 61 and the first lower branch 62 which are symmetrically arranged up and down, and can input the cooling medium from both ends of the large bolt 4 at the same time, effectively improving the cooling efficiency. The outer diameter of the medium input pipe 8 is smaller than the inner diameter of the through hole 411, and the medium input pipe 8 is in clearance fit with the through hole 411. After the cooling medium is output from the medium output hole 81, it moves out of the through hole 411 along the gap between the outer wall of the medium input pipe 8 and the inner wall of the through hole 411. Different steam turbines have different cylinders, and different cylinders have flange bolt holes 3 and large bolts 4 with different sizes. The medium input pipe 8 adopts a detachable and fixed connection method, and can select a suitable medium input pipe 8 according to different large bolts 4, effectively improving the applicable orientation. By adopting this technical measure, the working efficiency and the applicable range can be improved.

[0027] As Figure 2 shown, the medium output hole 81 is arranged in the middle of the medium input pipe 8. During actual use, the middle of the medium input pipe 8 corresponds to the middle of the through hole 411 of the double-headed screw 41. The first upper branch 61 and the first lower branch 62 simultaneously input the cooling medium into the medium input pipe 8, so that the cooling medium moves from the middle of the through hole 411 of the double-headed screw 41 to the upper and lower ends of the through hole 411, achieving uniform contact heat transfer and not generating large thermal stress.

[0028] As Figure 2As shown in the figure, both ends of the medium input pipe 8 are connected with a fixed cover 9 covering the nut 42; the fixed cover 9 is detachably and fixedly connected to the medium input pipe 8; the circumferential of the cover body of the fixed cover 9 is provided with medium discharge holes 91. In actual use, the nut 42 is a round nut, the fixed cover 9 is a barrel-shaped with a diameter slightly smaller than that of the nut 42, the opening direction of the fixed cover 9 faces the nut 42, and its end far from the nut 42 is a closed end, and the closed end is provided with a connection through hole. The fixed cover 9 is detachably and fixedly connected to one end of the medium input pipe 8 through a ferrule joint 92. Specifically, there are two ferrule joints 92. One end of the ferrule joint 92 on the upper side of the cylinder is detachably and fixedly connected to the upper end of the medium input pipe 8, and the other end is detachably and fixedly connected to the medium output end of the first upper branch 61; one end of the ferrule joint 92 on the lower side of the cylinder is detachably and fixedly connected to the lower end of the medium input pipe 8, and the other end is detachably and fixedly connected to the medium output end of the first lower branch 62; the two fixed covers 9 are respectively detachably and fixedly connected to the middle of the ferrule joint 92 through the connection through holes 411. Through the fixed cover 9 covering the nut 42, the nut 42 can be pressed. At the same time, after the cooling medium is discharged from the through hole 411 of the double-headed screw 41, it enters the fixed cover 9, which can cool the upper end of the double-headed screw 41 and the nut 42; the circumferential of the cover body of the fixed cover 9 is provided with a plurality of medium discharge holes 91 for discharging the cooling medium that has participated in cooling from the fixed cover 9.

[0029] As Figure 1 — Figure 3 As shown in the figure, the medium input through holes include an upper-side medium input through hole 11 and a lower-side medium input through hole 21 symmetrically arranged on the upper half 1 and the lower half 2 of the cylinder; the upper-side medium input through hole 11 and the lower-side medium input through hole 21 are respectively arranged at the lower part of the upper half 1 of the cylinder and the upper part of the lower half 2 of the cylinder; correspondingly, the second branch 7 includes a second upper branch 71 and a second lower branch 72 arranged in parallel; the medium discharge through holes include an upper-side medium discharge through hole 12 and a lower-side medium discharge through hole 22 symmetrically arranged on the upper half 1 and the lower half 2 of the cylinder. The upper-side medium discharge through hole 12 and the lower-side medium discharge through hole 22 are respectively arranged at the upper part of the upper half 1 of the cylinder and the lower part of the upper half 1 of the cylinder. In actual use, the upper-side medium input through hole 11, the lower-side medium input through hole 21, the upper-side medium discharge through hole 12, and the lower-side medium discharge through hole 22 have internal threads at the end far from the flange bolt hole 3; when the second upper branch 71 and the second lower branch 72 are made of hose material, a threaded pipe joint needs to be added for connection. After the large bolt 4 is cooled, it is necessary to block the upper-side medium input through hole 11, the lower-side medium input through hole 21, the upper-side medium discharge through hole 12, and the lower-side medium discharge through hole 22, and generally a threaded plug is used for blocking. By adopting this technical measure, it can prevent steam from leaking at the upper-side medium input through hole 11, the lower-side medium input through hole 21, the upper-side medium discharge through hole 12, and the lower-side medium discharge through hole 22 during the operation of the unit.

[0030] In actual use, flow regulating valves are respectively provided on the second upper branch 71 and the second lower branch 72. The upper-side medium input through-hole 11 and the lower-side medium input through-hole 21 are respectively arranged at the lower part of the upper half 1 of the cylinder and the upper part of the lower half 2 of the cylinder, so that the side medium input through-hole and the lower-side medium input through-hole 21 correspond to the middle part of the double-headed screw 41; the upper-side medium discharge through-hole 12 and the lower-side medium discharge through-hole 22 are respectively arranged at the upper part and the lower part of the upper half 1 of the cylinder, corresponding to the upper part and the lower part of the double-headed screw 41 respectively. By adopting this technical measure, uniform contact heat transfer can be carried out on the outer surface of the bolt, and no large thermal stress will be generated.

[0031] As Figure 3 shown, the upper-side medium input through-holes 11 and the lower-side medium input through-holes 21 are multiple longitudinally arranged ones. Correspondingly, the second upper branch 71 and the second lower branch 72 connected to the upper-side medium input through-holes 11 and the lower-side medium input through-holes 21 are multiple parallel pipelines; the number of the upper-side medium discharge through-holes 12 and the lower-side medium discharge through-holes 22 arranged longitudinally is the same as that of the upper-side medium input through-holes 11 and the lower-side medium input through-holes 21. Among them, the medium input through-holes and the side medium discharge through-holes are generally one to five longitudinally arranged ones on the premise of not affecting the strength and stiffness of the cylinder. By increasing the number of the medium input through-holes and the medium discharge through-holes, the cooling efficiency can be effectively improved.

[0032] As Figure 3 shown, the number of the upper-side medium discharge through-holes 12 and the lower-side medium discharge through-holes 22 arranged vertically is greater than or equal to three times the number of the upper-side medium input through-holes 11 and the lower-side medium input through-holes 21 arranged vertically. In actual use, the number of the upper-side medium input through-holes 11 and the lower-side medium input through-holes 21 arranged vertically is one group, and the number of the upper-side medium discharge through-holes 12 and the lower-side medium discharge through-holes 22 arranged vertically is three groups.

[0033] The cooling medium in the cooling medium storage device 10 is compressed air. In actual use, the cooling medium storage device 10 can adopt a compressed air tank, and the cooling medium is compressed air. Using compressed air as the cooling medium has the advantages of being easy to obtain, pollution-free, and can be directly discharged into the atmosphere; as the cooling medium, compressed air also has a lower density, stable heat transfer during the cooling process, the temperature of the bolt will not drop suddenly, and no large thermal stress will be generated.

[0034] The installation and disassembly method of the present invention.

[0035] I. Installation of the rapid cooling system After the large bolt 4 is electrically heated and the nut 42 is rotated in place, operate according to the following steps: Step 1. Installation of the first branch 6 inside the large bolt 4 Place the medium input pipe 8 into the through hole 441 of the large bolt 4. The two ends of the medium input pipe 8 are respectively connected to the ferrule fittings 92. The ferrule fittings 92 are connected to the fixed cover 9, and the fixed cover 9 is arranged to cover the nut 42; the outer end of the ferrule fitting 92 away from the medium input pipe 8 is connected to the first branch 6. A flow regulating valve is arranged on the first branch 6, and the first branch 6 is connected to the main pipeline 5; In actual use, the first branch 6 and the main pipeline 5 can be made of hose material.

[0036] Step 2. Installation of the second branch 7 for cooling the outside of the large bolt 4 Threaded pipe joints are screwed into the outer ends of the upper medium input through hole 11 and the lower medium input through hole 21. The threaded pipe joints are externally connected to the second branch 7. A flow regulating valve is arranged on the second branch 7; one end of the second branch 7 away from the threaded pipe joint is connected to the main pipeline 5.

[0037] Step 3. Installation of the main pipeline 5 The main pipeline medium output end of the main pipeline 5 is connected to the first branch 6 and the second branch 7. The main pipeline medium input end of the main pipeline 5 is connected to the cooling medium storage device 10; a stop valve is arranged on the main pipeline 5.

[0038] In actual use, the first branch 6, the second branch 7, and the main pipeline 5 can all be made of hose material.

[0039] II. Disassembly of the rapid cooling system The electric heating of the large bolt 4 is generally carried out for a group of four bolts simultaneously, and the cooling is also carried out for a group of four bolts simultaneously. After a group of bolts is cooled, it is disassembled according to the following steps and then transferred to the next group of bolts for installation. The cooling work of the next group of bolts is carried out.

[0040] Step 1. Disassembly of the first branch 6 for cooling the inside of the large bolt 4 Separate the first branch 6 from the ferrule fitting 92 and remove the first branch 6 connected to the ferrule fitting 92; remove the ferrule fitting 92; move the fixed cover 9 away, and then draw out the medium input pipe 8 from the through hole 441 of the large bolt 4; Step 2. Disassembly of the second branch 7 for cooling the outside of the large bolt 4 Remove the second branch 7, the flow regulating valve, and the threaded pipe joint at the upper medium input through hole 11 and the lower medium input through hole 21; Step 3. Plug the cooling holes on the outer wall of the bolt to prevent steam from leaking out at the cooling holes during the operation of the unit.

[0041] Use a threaded plug to plug the upper medium input through hole 11 and the lower medium input through hole 21; Use a threaded plug to plug the upper medium discharge through hole 12 and the lower medium discharge through hole 22.

[0042] By adopting this technical measure, the installation and disassembly of the rapid cooling system for multiple groups of large bolts can be completed quickly, effectively improving work efficiency.

[0043] An operating method for the rapid cooling system of large bolts of a steam turbine. After the large bolt 4 is heated, the general temperature is about 200 °C. The specific operating method includes the following steps: Step 1: During the cooling process, regularly measure the surface temperature of the large bolt 4 through an infrared thermometer; Step 2: Select the appropriate opening degree of the flow regulating valve according to the measured temperature of the large bolt 4 to control the flow rate of the cooling medium; When the temperature of the large bolt 4 is higher, the opening degree of the flow regulating valve is smaller; when the temperature of the large bolt 4 is lower, the opening degree of the flow regulating valve is larger.

[0044] During actual use, it is necessary to first open the stop valve on the main pipeline 5, and then select the appropriate opening degree of the flow regulating valve. The opening degree of the flow regulating valve includes the opening degrees of the flow regulating valves of the first branch 6 and the second branch 7. The opening degrees of the flow regulating valves of the first branch 6 and the second branch 7 are completely synchronized and the opening degrees are the same.

[0045] Among them, the specific steps of Step 2 are: Step 2.1: When the temperature of the large bolt 4 is higher than 200 °C Keep the opening degrees of the flow regulating valves on the first branch 6 and the second branch 7 at 4 - 7%.

[0046] Step 2.2: When the temperature of the large bolt 4 is between 150 - 200 °C Keep the opening degrees of the flow regulating valves on the first branch 6 and the second branch 7 at 13 - 17%.

[0047] Step 2.3: When the temperature of the large bolt 4 is between 100 - 150 °C, Keep the opening degrees of the flow regulating valves on the first branch 6 and the second branch 7 at 28 - 32%.

[0048] Step 2.4: When the temperature of the large bolt 4 is lower than 100 °C, Keep the opening degrees of the flow regulating valves on the first branch 6 and the second branch 7 at 100%.

[0049] Step 2.5: When the temperature of the large bolt 4 reaches the local air temperature, Keep the opening degrees of the flow regulating valves on the first branch 6 and the second branch 7 at 100%, maintain for 13 - 20 minutes, and then stop cooling.

[0050] In actual use, during the cooling process of the large bolt 4, it is necessary to regularly measure the surface temperature of the large bolt 4 through a temperature measuring device such as an infrared thermometer; and select an appropriate opening degree of the flow regulating valve according to the measured temperature of the large bolt 4, so as to control the flow rate of the compressed air for cooling. By adopting this technical measure, the rate of temperature reduction of the large bolt 4 can be effectively controlled. In actual use, since the heat transfer is fast and the temperature drops quickly when the temperature is high, the amount of compressed air for cooling required is small. Therefore, the higher the temperature of the large bolt 4, the smaller the opening degree of the flow regulating valve; the lower the temperature of the large bolt 4, the larger the opening degree of the flow regulating valve. At the same time, in step 2, the method of gradually reducing the temperature is adopted, which can make the temperature of the large bolt 4 drop evenly, and the thermal stress of the bolt is small.

[0051] Embodiment 2 As Figure 4 shown, other contents of this embodiment are the same as those of Embodiment 1, the difference is that: the medium output hole 81 is composed of a plurality of small holes arranged in the middle of the medium input pipe 8. By adopting this technical measure, the cooling medium can be more evenly dispersed when output, avoiding the impact or instability phenomenon caused by overly concentrated air flow. At the same time, the plurality of small holes can also increase the resistance when the air flow passes through, so as to play a role in throttling, speed regulation or pressure reduction. Specifically, a plug 83 is provided at the middle position of the medium input pipe 8, and upper side medium output holes 8011 and lower side medium output holes 8021 which are evenly distributed in a circumferential direction in three to seven layers on the pipe body of the medium input pipe 8 are respectively provided on the upper and lower sides of the plug 83.

[0052] Furthermore, the medium input pipe 8 can be composed of a combined upper side medium input pipe 801 and a lower side medium input pipe 802 which are symmetrically arranged; a plurality of upper side medium output holes 8011 are provided at the lower end of the upper side medium input pipe 801, and a plurality of lower side medium output holes 8021 are provided at the upper end of the lower side medium input pipe 802; the upper side medium input pipe 801 and the lower side medium input pipe 802 are respectively connected with the upper and lower ends of the plug 83 in an interference fit. By adopting this technical measure, it has the advantages of flexible structure, convenient storage, and can be combined according to actual needs.

[0053] The technical solutions provided by the embodiments of the present invention have been introduced in detail above. Specific examples are used in this article to elaborate on the principles and implementation manners of the embodiments of the present invention. The descriptions of the above embodiments are only applicable to help understand the principles of the embodiments of the present invention; at the same time, for those of ordinary skill in the art, according to the embodiments of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A system for rapidly cooling large bolts of a steam turbine, the steam turbine comprising an upper cylinder half and a lower cylinder half symmetrically arranged in a vertical direction, wherein the upper cylinder half and the lower cylinder half are provided with communicating flange bolt holes; the large bolt comprises a double-headed screw having a through hole and a nut matched with the screw, and the double-headed screw is clearance-matched with the flange bolt hole, It is characterized in that The rapid cooling system includes a pipeline system and a cooling medium storage device; The pipeline system includes a main pipeline, a first branch pipeline and a second branch pipeline for cooling the inside and outside of the large bolt; One end of the main line is connected to the cooling medium storage device, and the other end thereof is connected in parallel with the first branch line and the second branch line; One end of the first branch is connected to the main branch, and the other end thereof has a diameter smaller than the through hole of the double-headed screw and is disposed in the through hole; One side of the cylinder of the steam turbine is provided with a medium input through hole and a medium discharge through hole which are connected with the flange bolt hole; One end of the second branch is connected to the main pipeline, and the other end thereof is connected to the medium input through hole.

2. The large bolt rapid cooling system for steam turbine according to claim 1, characterized in that: The first branch includes a first upper branch and a first lower branch symmetrically arranged in upper and lower parts; a medium input pipeline matching the clearance of the through hole is provided in the through hole of the double-headed screw; The medium input pipe has a medium output hole for outputting the medium on its body; Two ends of the medium input pipe extend out of two ends of the through hole and are detachably fixedly connected to the first upper branch medium output end and the first lower branch medium output end of the first upper branch and the first lower branch, respectively.

3. The large bolt rapid cooling system for steam turbine according to claim 2, characterized in that: The medium output hole is arranged in the middle of the medium input pipe.

4. The large bolt rapid cooling system for steam turbine according to claim 2, characterized in that: Both ends of the medium input pipe are connected with fixed covers which are covered on nuts; The fixed cover is detachably fixedly connected to the medium input pipe; The cover body of the fixed cover is circumferentially provided with medium discharge holes.

5. The large bolt rapid cooling system for steam turbine according to claim 1, characterized in that: The medium input through hole comprises an upper medium input through hole and a lower medium input through hole symmetrically arranged at the upper half of the cylinder and the lower half of the cylinder; the upper medium input through hole and the lower medium input through hole are respectively arranged at the lower part of the upper half of the cylinder and the upper part of the lower half of the cylinder; correspondingly, the second branch comprises a second upper branch and a second lower branch arranged in parallel; The medium discharge through hole comprises an upper medium discharge through hole and a lower medium discharge through hole symmetrically arranged on the upper half and the lower half of the cylinder; The upper medium discharge through hole and the lower medium discharge through hole are respectively arranged at the upper part of the upper half of the cylinder and the lower part of the upper half of the cylinder.

6. The large bolt rapid cooling system for steam turbine according to claim 5, characterized in that: The upper medium input through hole and the lower medium input through hole are multiple and arranged longitudinally, and correspondingly, the second upper branch and the second lower branch connected to the upper medium input through hole and the lower medium input through hole are multiple pipes connected in parallel; The number of the upper medium discharge through holes and the lower medium discharge through holes arranged in the longitudinal direction is the same as that of the upper medium input through holes and the lower medium input through holes.

7. The large bolt rapid cooling system for steam turbine according to claim 6, characterized in that: The number of the upper medium discharge through holes and the lower medium discharge through holes arranged in the vertical direction is greater than or equal to three times the number of the upper medium input through holes and the lower medium input through holes arranged in the vertical direction.

8. The large bolt rapid cooling system for a steam turbine according to claim 1, characterized in that: The cooling medium in the cooling medium storage device is compressed air.

9. An operating method of a large bolt rapid cooling system for a steam turbine according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: During the cooling process, the surface temperature of the large bolt is measured regularly by an infrared thermometer; Step 2: According to the measured temperature of the large bolt, select the appropriate opening of the flow regulating valve to control the flow of the cooling medium; When the temperature of the large bolt is higher, the opening of the flow control valve is smaller; when the temperature of the large bolt is lower, the opening of the flow control valve is larger.

10. The operating method of the steam turbine large bolt rapid cooling system according to claim 9, characterized in that: The specific steps of step 2 are: Step 2.1: When the temperature of the large bolt is higher than 200°C Keep the opening of the flow control valves on the first branch and the second branch at 4~7%; Step 2.2: When the temperature of the large bolt is between 150-200℃ Keep the opening of the flow control valves on the first branch and the second branch at 13-17%; Step 2.3: When the temperature of the large bolt is between 100-150℃ Keep the opening of the flow control valves on the first branch and the second branch at 28-32%; Step 2.4: When the temperature of the large bolt is below 100°C Keep the opening of the flow control valves on the first branch and the second branch at 100%; Step 2.5: When the temperature of the large bolt reaches the local air temperature Keep the flow regulating valves on the first branch and the second branch open at 100% for 13-20 minutes, and then stop cooling.

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