CN111396150B

CN111396150B - Method for solving problem of high temperature of bearing bush of steam turbine set in power station

Info

Publication number: CN111396150B
Application number: CN202010105150.4A
Authority: CN
Inventors: 柳桐; 郭宝仁; 王政先; 王健; 王丽萍
Original assignee: Huadian Electric Power Research Institute Co Ltd
Current assignee: Huadian Electric Power Research Institute Co Ltd
Priority date: 2020-02-20
Filing date: 2020-02-20
Publication date: 2023-02-17
Anticipated expiration: 2040-02-20
Also published as: CN111396150A

Abstract

The invention discloses a method for solving the problem of high temperature of bearing bushes of a steam turbine unit of a power station, which is characterized in that regulating valves are respectively arranged between an oil supply branch pipe and each bearing bush, a pressure transmitter is added, and the regulating valves are used for automatically regulating the oil supply amount of lubricating oil in real time, so that the temperature of the bearing bushes with problems is reduced, the bearing bushes are ensured not to be over-heated in operation, and the safety and stability of the operation of a steam turbine are improved.

Description

Method for solving problem of high temperature of bearing bush of steam turbine set in power station

Technical Field

The invention relates to an automatic distribution, adjustment and transformation of lubricating oil supply of a turbine and a generator bearing of a power station and an automatic control logic idea of an oil supply regulating valve.

Background

The bearing is an important component of the steam turbine, and the overhigh temperature of the pad block can cause the damage of the bearing in different degrees, even can cause the unplanned shutdown of the unit, and brings hidden troubles to the electric power safety production. The steam turbine bearing is a sliding bearing based on the oil film lubrication theory, and lubricating oil with temperature and pressure meeting the requirements is continuously provided by a lubricating oil pump. The rotor rotates at a high speed on the bearing bush poured with the babbit alloy, so that an oil film is formed between the rotor and the bearing bush to form liquid friction, and therefore friction resistance is reduced. The heat generated by friction can be taken away by the return oil in time, so that the temperature of the bearing bush can be always kept in a required range. Taking a 300MW steam turbine set of a certain plant as an example, the total number of the radial bearings is 6, and the main oil pump driven by a steam turbine supplies oil averagely. Wherein, the steam turbine includes 4 radial axle bushes, and the generator includes 2 radial axle bushes, respectively has into oil pipe and time oil pipe respectively, but all gathers together through the oil return sleeve pipe. The radial bearing is also called a support bearing, the diameter of the inner circle of the bearing bush is slightly larger than the outer diameter of the shaft neck, when the rotor is static, the shaft neck is positioned at the bottom of the bearing bush, and a wedge-shaped gap is naturally formed between the shaft neck and the bearing bush. If lubricant with a certain pressure and viscosity is continuously supplied to the bearing gap, the lubricant rotates as the journal rotates, and in the gap on the right side, the lubricant is carried from the wide opening to the narrow opening. Because the inlet oil quantity of the gap is larger than the outlet oil quantity, the lubricating oil is gathered in the narrow wedge-shaped gap, and the oil pressure is increased. When the oil pressure in the clearance exceeds the load on the journal, the journal is lifted. After the journal is lifted, the clearance is increased, the oil pressure is reduced, and the journal falls down a little, until the oil pressure in the clearance is balanced with the load, the journal rotates stably at a certain position. At this time, the journal and the bearing bush are completely separated by an oil film, and liquid friction is formed. The radial bearing of the steam turbine is divided into a fixed pad bearing and a tilting pad bearing.

At present, a bearing oil supply system of a steam turbine unit of a power plant still adopts a traditional oil supply distribution mode, a main oil pump driven by a steam turbine supplies oil averagely in a normal operation stage, and an alternating-current lubricating oil pump supplies oil averagely in a starting and stopping stage. As shown in fig. 1, the technical defects of the existing oil supply device for the turbine bearing are as follows: (1) The oil supply of each tile is influenced by factors such as the design type of the tile body, the installation process, the weight of the rotor and the like, and the tile has no adjustability and almost average oil supply; (2) In the actual operation process of the steam turbine, the stress conditions of all the tiles are different, so that the temperature of the tile blocks is different, the problem that the temperature of the bearing bush for average oil supply is high cannot be eliminated, and the bearing bush is damaged in different degrees if the temperature is further increased; (3) No oil supply pressure monitoring measuring point is arranged in the design of the existing lubricating oil system, and once a tile block is blocked by oil sludge or impurities, the temperature rise cannot be timely distinguished from other problems.

The invention is provided by combining the past fault diagnosis and analysis and field processing experience of the problem of overtemperature of the bearing bush of the power station steam turbine, so that the running temperature of the problem bearing bush is reduced by redistribution of the oil supply quantity, the running safety and stability of the power station steam turbine are further ensured, and accidents such as bush burning or bush melting are reduced.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a simple, economical and efficient power station turbine unit bearing oil supply distribution and adjustment scheme, so that the problem of high temperature of a radial bearing is solved.

The technical scheme adopted by the invention for solving the problems is as follows: a solution for high temperature of a bearing bush of a steam turbine unit of a power station is characterized by comprising distribution transformation of bearing oil supply of the steam turbine unit and automatic control logic design of an oil supply regulating valve; the bearing of the steam turbine set comprises a steam turbine bearing and a generator bearing, a regulating valve is additionally arranged on a bearing oil supply pipeline, a pressure transmitter is additionally arranged behind the regulating valve, and the regulating valve is logically controlled according to the characteristic of bearing oil supply.

Furthermore, the turbine bearing and the generator bearing are radial support bearings, the regulating valves are respectively installed between the branch oil supply pipe and each bearing bush, and the pressure transmitter is installed on the side of the branch oil supply pipe and behind the regulating valves, so that the flow of lubricating oil of a normal bearing is reduced through the opening of the regulating valves under the logic control, and the oil supply quantity of a problem bearing is further improved.

Further, the steam turbine bearing comprises No. 1 to No. 6 radial support bearings for discharging steam of a large double-low pressure cylinder and No. 1 to No. 4 radial support bearings for small and medium single-low pressure cylinder units; the lowest mechanical limit of 30 percent is provided for the regulating valve, so that the oil of each tile is ensured to be continuously cut off; the regulating valve is set to be of a power-off and air-off valve position retaining type.

Compared with the prior art, the invention has the following advantages and effects:

(1) By additionally arranging the distribution regulating valve on each bearing pipeline branch, the oil supply of the bearing with the problem can be regulated in real time according to the temperature of the bearing at different load stages of the unit, different distribution of the oil supply of each bearing bush is realized, and the temperature of the bearing with the problem is reduced; (2) Optimizing oil supply and return monitoring measuring points of each tile, monitoring oil supply pressure data of each tile more comprehensively and accurately, finding problems such as blockage of each tile in time and the like so as to take measures, prevent accident expansion and ensure safe operation of the steam turbine; (3) The automatic control logic idea of the regulating valve is provided according to the characteristics of the bearing, the oil supply quantity of the bearing is automatically regulated, and the aim of indirectly controlling the temperature of the bearing is fulfilled.

Drawings

FIG. 1 is a schematic structural diagram of a supply oil return path and an oil return path of a modified front bearing in an embodiment of the invention.

Fig. 2 is a schematic structural diagram of a supply oil return path and an oil return path of a modified bearing in the embodiment of the invention.

FIG. 3 is a logic control flow chart of a bearing lubrication regulating valve (300 MW unit) in the embodiment of the invention.

Detailed Description

The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.

Examples

Referring to fig. 2 to 3, in the embodiment, a method for solving the problem of high temperature of the bearing bush of the steam turbine set in the power station is used for real-time distribution and adjustment of the oil supply flow of the bearing under different working conditions, the adjusting valves are respectively installed between the oil supply branch pipes and the bearing bushes, the pressure transmitter is added, the adjustment of the oil supply amount of the lubricating oil is automatically performed in real time through the adjusting valves, the temperature of the bearing bush in a problem is reduced, the bearing bush is guaranteed not to be over-heated during operation, and the safety and stability of the operation of the steam turbine are improved.

The following is an automatic distribution and adjustment method for bearing oil supply of a 300MW turboset.

Step 1: cutting off the bearing oil supply branch pipe and installing a regulating valve when the lubricating oil system is in a shutdown state;

and 2, step: a hole is formed in the back of the oil pressure regulating valve, and a pressure gauge or a pressure transmitter is installed;

and step 3: temporary short-circuit of the bearing oil inlet and return pipelines, washing and filtering at a large flow rate, removing the temporary short-circuit pipelines after the indexes of lubricating oil are qualified, and formally connecting the oil inlet and return pipelines of each tile;

and 4, step 4: testing the oil quality again, and circulating the lubricating oil in each bearing bush after the lubricating oil is qualified;

and 5: the regulating valves installed on all the tiles are statically debugged, so that flexible and reliable actions are guaranteed, and the regulating curves are smooth;

and 6: under the static condition of the steam turbine, according to the past experience, the temperature of the No. 2 bearing bush is higher, the coarse adjustment is manually carried out, the regulating valves corresponding to the No. 1, the No. 3, the No. 4, the No. 5 and the No. 6 are closed to 90 percent, and the opening degree of the regulating valve corresponding to the No. 2 bearing bush is kept to be 100 percent;

and 7: after 3000rpm of the steam turbine, the regulating valve is automatically controlled, at the moment, the temperature of No. 1 tile is 75 ℃, the temperature of No. 2 tile is 86 ℃, the temperature of No. 3 tile is 71 ℃, the temperature of No. 4 tile is 76 ℃, the temperature of No. 5 tile is 67 ℃, the temperature of No. 6 tile is 62 ℃, the temperature of each tile is less than the set value 95 ℃, the valve position of the regulating valve corresponding to each tile is maintained, and the regulating valve does not participate in adjustment;

and 8: after the steam turbine is provided with 25% load, the regulating valve is in an automatic control state, at the moment, the temperature of No. 1 tile is 77 ℃, the temperature of No. 2 tile is 89 ℃, the temperature of No. 3 tile is 75 ℃, the temperature of No. 4 tile is 78 ℃, the temperature of No. 5 tile is 68 ℃ and the temperature of No. 6 tile is 66 ℃, the temperature of each tile does not exceed the set value of 95 ℃, the valve position is maintained, and the regulating valve does not participate in regulation;

and step 9: after the turbine is loaded with 50%, the regulating valve is in an automatic control state, at the moment, the temperature of No. 1 tile is 79 ℃, the temperature of No. 2 tile is 93 ℃, the temperature of No. 3 tile is 74 ℃, the temperature of No. 4 tile is 75 ℃, the temperature of No. 5 tile is 68 ℃ and the temperature of No. 6 tile is 64 ℃, the temperature of each tile does not exceed the set value of 95 ℃, the valve position is maintained, and the regulating valve does not participate in regulation;

step 10: after the steam turbine is 75% loaded, the regulating valve is in an automatic control state, at the moment, the temperature of No. 1 tile is 78 ℃, the temperature of No. 2 tile is 97 ℃, the temperature of No. 3 tile is 72 ℃, the temperature of No. 4 tile is 78 ℃, the temperature of No. 5 tile is 68 ℃ and No. 6 tile is 64 ℃, the temperature of No. 2 tile exceeds a set value of 95 ℃, the regulating valves corresponding to No. 1, no. 3, no. 4, no. 5 and No. 6 tile are logically and automatically switched by 1%, and the opening degree of each valve is reduced to 89%; delaying for 10 seconds, if 95 ℃ of No. 2 tile is still higher than a set value, logically continuing to close 1% of regulating valves corresponding to No. 1, no. 3, no. 4, no. 5 and No. 6 tiles, and reducing the opening of each valve to 88% \8230 \8230whichis performed until the opening of each valve is reduced to 86%, and the temperature of No. 2 tile is lower than the set value of 95 ℃, keeping the valve position, and not participating in the regulation of the regulating valves, wherein the temperature of No. 1 tile 79 ℃, no. 2 tile 94 ℃, no. 3 tile 76 ℃, no. 4 tile 79 ℃, no. 5 tile 70 ℃ and No. 6 tile 67 ℃;

step 11: after the steam turbine is loaded with 100%, the regulating valve is in an automatic control state, at the moment, the temperature of the No. 1 tile is 80 ℃, the temperature of the No. 2 tile is 95 ℃, the temperature of the No. 3 tile is 75 ℃, the temperature of the No. 4 tile is 78 ℃, the temperature of the No. 5 tile is 73 ℃ and the temperature of the No. 6 tile is 67 ℃, the temperature of the No. 2 tile exceeds a set value of 95 ℃, the regulating valves corresponding to the No. 1, the No. 3, the No. 4, the No. 5 and the No. 6 tiles are automatically closed by 1% through logic judgment, but the temperature of the No. 1 tile reaches 80 ℃ (a set threshold value), the regulating valves corresponding to the No. 1 tile are automatically skipped by the logic, the regulating valves corresponding to the No. 3 to the No. 6 tiles are closed by 1%, at the moment, the opening degree of the regulating valves corresponding to the No. 1 tile is 86%, the opening degree of the regulating valves corresponding to the No. 2 tile is 100%, the opening degree of the No. 3 to the No. 6 tiles is 85%, the opening degree of the No. 1 tile 80 ℃, the No. 2 tile 94 ℃, the No. 2 tile, the No. 3 tile is 77 tile, the No. 4 tile is 72 ℃, the No. 6 tile is lower than the set value of the No. 6 tile 66 ℃, and the temperature of the No. 2 tile is lower than the set value of the 95 ℃, and the valve position is kept;

step 12: in the automatic adjustment process of the regulating valve, closely monitoring whether the unit operation parameters fluctuate greatly, and checking whether the normal operation requirements of the unit are met;

step 13: the steam turbine is provided with 100% load, the running conditions (shaft vibration, bearing bush temperature and the like) of the unit are closely monitored, and if abnormal phenomena occur, the load rise or the load drop is stopped; stably running and checking for 24 hours under the condition of no abnormity;

step 14: after stable operation is checked for 24 hours, reducing the load from 100% to 20%, observing the change condition of the tile temperature and the action condition of a valve, and monitoring whether the operation parameters of the unit are largely fixed or not and whether the operation parameters such as the tile temperature, the oil return temperature, the unit vibration and the like are stable or not in real time; then, the load is increased from 20% to 100%, the problem temperature change condition and the tracking condition of the rest tile regulating valves are observed, and whether the operation parameters of the unit are largely fixed or not and whether the operation parameters such as tile temperature, oil return temperature and unit vibration are stable or not are monitored in real time;

step 15: after the debugging and examination are completed, the lubricating oil regulating valve is put into operation formally, under the load of different units, the lubricating oil regulating valve is adjusted in real time according to the temperature of the tile, the temperature of the problem tile is always kept to be lower than 95 ℃ (the temperature of the problem tile is adjustable according to different units), and the temperature of other tiles is not higher than 80 ℃ (the temperature of the other tiles is adjustable according to different units).

Those not described in detail in this specification are well within the skill of the art.

Although the present invention has been described with reference to the above embodiments, it should be understood that the scope of the present invention is not limited thereto, and that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A solution for high temperature of bearing bushes of a steam turbine set of a power station is characterized by comprising the steps of distribution transformation of bearing oil supply of the steam turbine set and automatic control logic design of an oil supply regulating valve; the bearing of the steam turbine set comprises a steam turbine bearing and a generator bearing, a regulating valve is additionally arranged on a bearing oil supply pipeline, a pressure transmitter is additionally arranged behind the regulating valve, and the regulating valve is logically controlled according to the characteristic of bearing oil supply;

the turbine bearing and the generator bearing are radial support bearings, the regulating valves are respectively arranged between the branch oil supply pipe and each bearing bush, and the pressure transmitter is arranged on the side of the branch oil supply pipe and behind the regulating valves, so that the lubricating oil flow of a normal bearing is reduced by logically controlling the opening of the regulating valves, and the oil supply quantity of a problem bearing is further improved;

the steam turbine bearing comprises No. 1 to No. 6 radial support bearings for exhausting steam of a large double low-pressure cylinder and No. 1 to No. 4 radial support bearings for small and medium single low-pressure cylinder units; the lowest mechanical limit of 30 percent is provided for the regulating valve, so that the oil of each tile is ensured to be continuously cut off; the regulating valve is set to be of a power-off and air-off valve position retaining type.