Rules for operating steam turbines. Diagnostics. Steam turbines

The operating parameters of the steam turbine control system must satisfy Russian state standards and technical specifications for the supply of turbines.

The degree of uneven regulation of steam pressure in regulated extractions and back pressure must satisfy the consumer's requirements, agreed upon with the turbine manufacturer, and prevent the safety valves (devices) from tripping.

All inspections and tests of the turbine overspeed control and protection system must be carried out in accordance with the instructions of the turbine manufacturers and current governing documents.

The safety circuit breaker must operate when the turbine rotor speed increases by 10 - 12% above the nominal value or to the value specified by the manufacturer.

When the safety circuit breaker is triggered, the following must close:

    stop, control (stop-control) valves for fresh steam and reheat steam;

    stop (shut-off), control and check valves, as well as control diaphragms and steam extraction dampers;

    shut-off valves on steam pipelines connecting with third-party sources of steam.

The turbine protection system against increased rotor speed (including all its elements) must be tested by increasing the rotation speed above the rated speed in the following cases:

a) after installation of the turbine;

b) after major repairs;

c) before testing the control system by load shedding with disconnection of the generator from the network;

d) during startup after disassembling the safety circuit breaker;

e) during startup after a long (more than 3 months) idle time of the turbine, if it is not possible to check the operation of the strikers of the safety circuit breaker and all protection circuits (with impact on the actuators) without increasing the rotation speed above the nominal one;

e) during startup after the turbine has been idle in reserve for more than 1 month. if it is not possible to check the operation of the safety breakers and all protection circuits (with impact on the executive bodies) without increasing the rotation speed above the nominal one;

g) during startup after disassembling the control system or its individual components;

h) during scheduled tests (at least once every 4 months).

In cases “g” and “h”, it is allowed to test the protection without increasing the rotation speed above the nominal (in the range specified by the turbine manufacturer), but with mandatory verification of the operation of all protection circuits.

Tests of turbine protection by increasing rotation speed must be carried out under the guidance of the workshop manager or his deputy.

The tightness of the live steam stop and control valves should be checked by testing each group separately.

The density criterion is the turbine rotor speed, which is set after the valves being tested are completely closed at full (nominal) or partial steam pressure in front of these valves. The permissible value of the rotation speed is determined by the manufacturer's instructions or current governing documents, and for turbines, the testing criteria for which are not specified in the manufacturer's instructions or current governing documents should not be higher than 50% of the nominal value at the nominal parameters in front of the valves being tested and the nominal exhaust pressure pair.

When all stop and control valves are closed simultaneously and the fresh steam and back pressure (vacuum) are at nominal parameters, passing steam through them should not cause rotation of the turbine rotor.

Checking the tightness of the valves should be carried out after installing the turbine, before testing the safety circuit breaker by increasing the rotation speed, before stopping the turbine for a major overhaul, during startup after it, but at least once a year. If signs of a decrease in valve density are detected during turbine operation, an extraordinary check of their density must be carried out.

Stop and control valves for fresh steam, stop (shut-off) and control valves (diaphragms) for steam extraction, shut-off valves on steam pipelines connecting with third-party steam sources should move: to full speed- before starting the turbine and in cases provided for by the manufacturer’s instructions; for part of the stroke - every day during turbine operation.

When moving the valves to full stroke, the smoothness of their movement and seating must be checked.

The tightness of the check valves of regulated extractions and the operation of the safety valves of these extractions must be checked at least once a year and before testing the turbine for load shedding.

Check valves of regulated heating steam extractions, which are not connected to the extractions of other turbines, ROU and other steam sources, do not need to be tested for density unless there are special instructions from the manufacturer.

The seating of check valves of all extractions must be checked before each start-up and when stopping the turbine, and during normal operation periodically according to a schedule determined by the technical manager of the power plant, but at least once every 4 months.

If the check valve is faulty, operation of the turbine with appropriate steam extraction is not allowed.

Checking the closing time of stop (protective, shut-off) valves, as well as reading the characteristics of the control system with the turbine stopped and when it is idling, should be carried out:

    after installation of the turbine;

    immediately before and after a major overhaul of the turbine or repair of the main components of the control or steam distribution system.

Tests of the turbine control system by instantaneous load shedding corresponding to the maximum steam flow must be performed:

    when accepting turbines into operation after installation;

    after reconstruction that changes the dynamic characteristics of the turbine unit or the static and dynamic characteristics of the control system.

If deviations in the actual characteristics of regulation and protection from standard values ​​are detected, valve closing time increases beyond those specified by the manufacturer or in local instructions, or their density deteriorates, the causes of these deviations must be identified and eliminated.

The operation of turbines with a power limiter put into operation is permitted as a temporary measure only under the conditions of the mechanical condition of the turbine installation with the permission of the technical manager of the power plant. In this case, the turbine load must be lower than the limiter setting by at least 5%.

Shut-off valves installed on the lines of the lubrication, regulation and sealing systems of the generator, the erroneous switching of which can lead to shutdown or damage to the equipment, must be sealed in the operating position.

Before starting up a turbine after a medium or major overhaul, the serviceability and readiness to turn on the main and auxiliary equipment, instrumentation, remote and automatic control devices, process protection devices, interlocks, information and operational communications must be checked. Any defects identified must be corrected.

Before starting a turbine from a cold state (after it has been in reserve for more than 3 days), the following must be checked: the serviceability and readiness for switching on of equipment and instrumentation, as well as the operability of remote and automatic controls, process protection devices, interlocks, information and operational communications; passing technological protection commands to all actuators; serviceability and readiness to turn on those facilities and equipment on which repair work was carried out during downtime. Any malfunctions identified must be eliminated before start-up.

The start-up of the turbine should be supervised by the workshop shift supervisor or senior machinist, and after a major or medium repair - by the workshop supervisor or his deputy.

Starting the turbine is not allowed in the following cases:

    deviations of indicators of the thermal and mechanical conditions of the turbine from the permissible values ​​regulated by the turbine manufacturer;

    malfunction of at least one of the protections acting to stop the turbine;

    the presence of defects in the control and steam distribution systems, which can lead to turbine acceleration;

    malfunction of one of the oil lubrication pumps, regulation, generator seals or their automatic switching devices (AVR);

    deviations in oil quality from the standards for operating oils or a drop in oil temperature below the limit set by the manufacturer;

    deviations in fresh steam quality chemical composition from normal

Without turning on the turning device, supplying steam to the turbine seals, discharging hot water and steam into the condenser, and supplying steam to warm up the turbine are not allowed. The conditions for supplying steam to a turbine that does not have a shaft turning device are determined by local instructions.

The discharge of the working medium from the boiler or steam lines into the condenser and the supply of steam to the turbine to start it must be carried out at steam pressures in the condenser specified in the instructions or other documents of the turbine manufacturers, but not higher than 0.6 (60 kPa).

When operating turbine units, the mean square values ​​of the vibration velocity of the bearing supports should be no higher than 4.5 mm s -1.

If the standard vibration value is exceeded, measures must be taken to reduce it within no more than 30 days.

When vibration exceeds 7.1 mm s -1, it is not allowed to operate turbine units for more than 7 days, and when vibration is 11.2 mm s -1, the turbine must be turned off by protection or manually.

The turbine must be stopped immediately if, in steady state, there is a simultaneous sudden change in the vibration of the rotation frequency of two supports of one rotor, or adjacent supports, or two vibration components of one support by 1 mm s -1 or more from any initial level.

The turbine must be unloaded and stopped if, within 13 days, there is a smooth increase in any vibration component of one of the bearing supports by 2 mm·s -1.

Operation of the turbine unit during low-frequency vibration is unacceptable. If low-frequency vibration exceeding 1 mm·s -1 occurs, measures must be taken to eliminate it.

Temporarily, until equipped with the necessary equipment, vibration control based on the range of vibration displacement is allowed. In this case, long-term operation is allowed with a vibration range of up to 30 microns at a rotation speed of 3000 and up to 50 microns at a rotation speed of 1500; a change in vibration by 12 mm s -1 is equivalent to a change in the amplitude of vibrations by 1020 µm at a rotation speed of 3000 and 2040 µm at a rotation speed of 1500.

Vibration of turbine units with a power of 50 MW or more should be measured and recorded using stationary equipment for continuous vibration monitoring of bearing supports that meets state standards.

To monitor the condition of the turbine flow path and its contamination with salts, the values ​​of steam pressure in the control stages of the turbine should be checked at least once a month at close to nominal steam flow rates through the controlled compartments.

The increase in pressure in the control stages compared to the nominal one at a given steam flow rate should be no more than 10%. In this case, the pressure should not exceed the limit values ​​​​set by the manufacturer.

When the pressure limits in the control stages are reached due to salt deposits, the turbine flow path must be flushed or cleaned. The method of flushing or cleaning should be selected based on the composition and nature of the deposits and local conditions.

During operation, the efficiency of a turbine installation must be constantly monitored through a systematic analysis of indicators characterizing the operation of the equipment.

To identify the reasons for the decrease in the efficiency of a turbine installation and assess the effectiveness of repairs, operational (express) tests of the equipment must be carried out.

The turbine must be immediately stopped (disconnected) by personnel if the protection fails or is absent in the following cases:

    increasing the rotor speed above the safety circuit breaker setting;

    unacceptable axial shift of the rotor;

    unacceptable change in the position of the rotors relative to the cylinders;

    unacceptable decrease in oil pressure (fire-resistant liquid) in the lubrication system;

    unacceptable drop in oil level in the oil tank;

    an unacceptable increase in oil temperature at the drain from any bearing, generator shaft seal bearings, or any turbo unit thrust bearing block;

    ignition of oil and hydrogen on a turbine unit;

    an unacceptable decrease in the oil-hydrogen pressure difference in the turbogenerator shaft seal system;

    an unacceptable decrease in the oil level in the damper tank of the oil supply system for the turbogenerator shaft seals;

    turning off all oil pumps of the hydrogen cooling system of the turbogenerator (for non-injector oil supply schemes for seals);

    shutdown of the turbogenerator due to internal damage;

    unacceptable increase in pressure in the condenser;

    unacceptable pressure drop at the last stage of turbines with back pressure;

    sudden increase in vibration of the turbine unit;

    the appearance of metallic sounds and unusual noises inside the turbine or turbogenerator;

    the appearance of sparks or smoke from bearings and end seals of a turbine or turbogenerator;

    unacceptable decrease in the temperature of fresh steam or steam after reheating;

    the appearance of hydraulic shocks in the steam lines of fresh steam, reheating or in the turbine;

    detection of a rupture or through crack in non-disconnectable sections of oil pipelines and pipelines of the steam-water path, steam distribution units;

    stopping the flow of cooling water through the turbogenerator stator;

    unacceptable reduction in cooling water consumption for gas coolers;

    loss of voltage on remote and automatic control or at all instrumentation;

    the appearance of a circular fire on the slip rings of the rotor of a turbogenerator, auxiliary generator or exciter manifold;

    failure of the software and hardware complex of the automated process control system, leading to the impossibility of managing or monitoring all equipment of the turbine installation.

The need to break the vacuum when shutting down the turbine must be determined by local regulations in accordance with the manufacturer's instructions.

The local instructions must provide clear instructions about unacceptable deviations in the values ​​of controlled quantities for the unit.

The turbine must be unloaded and stopped within a period determined by the technical manager of the power plant (with notification to the power system dispatcher), in the following cases:

    jamming of stop valves of fresh steam or steam after reheating;

    jamming of control valves or breakage of their rods; jamming of rotary diaphragms or check valves;

    malfunctions in the control system;

    disruption of the normal operation of auxiliary equipment, circuitry and communications of the installation, if eliminating the causes of the disruption is impossible without stopping the turbine;

    increase in vibration of supports above 7.1 mm·s -1;

    identifying malfunctions of technological protections acting to stop equipment;

    detection of oil leaks from bearings, pipelines and fittings that create a fire hazard;

    detection of fistulas in sections of steam-water pipelines that cannot be disconnected for repair;

    deviations in the quality of fresh steam in terms of chemical composition from the norms;

    detection of unacceptable concentrations of hydrogen in bearing housings, conductors, oil tank, as well as hydrogen leakage from the turbogenerator housing that exceeds the norm.

For each turbine, the duration of the rotor run-out must be determined during shutdown with normal exhaust steam pressure and during shutdown with vacuum failure. When changing this duration, the reasons for the deviation must be identified and eliminated. The duration of the run-down must be monitored during all shutdowns of the turbine unit.

When placing a turbine into reserve for a period of 7 days or more, measures must be taken to preserve the equipment of the turbine installation.

Thermal testing of steam turbines must be carried out.

TPA maintenance can be divided into the following stages:

    Preparing the turbine for operation and starting;

    Maintenance during operation;

    Withdrawal and drainage;

    Monitoring the turbine during inactivity.

Preparing the turbine unit for operation

Preparing a steam turbine unit for warming up begins with checking the condition of the unit and servicing systems.

To do this you need to do the following:

    Prepare turbines and gears, i.e. inspect turbines and gears and ensure that all standard instrumentation is available and in good working order. Check the condition of the housing expansion indicators and sliding supports. Take measurements of the axial and radial position of the shafts and the axial position of the housings.

    Prepare and commission the oil system.

To do this you need:

    Remove settled water and sludge from oil tanks;

    Check the oil level in waste and pressure gravity tanks;

    In case of low oil temperature, heat it to 30...35 0 WITH, while ensuring that the heating steam pressure does not exceed 0.11...0.115 MPa;

    Start the oil separator and put it into operation;

    Prepare the filters and oil cooler for operation, open the corresponding valves and blades;

    Prepare for start-up and start the oil pump;

    Open the air valves on the filter, oil coolers on all turbine bearing and gear caps, release the air and check that the oil system is filled with oil;

    Check the supply of oil to lubricate the gear teeth, if necessary, by opening the inspection hatches for this;

    Make sure that the pressure in the lubrication and regulation systems corresponds to the values ​​​​specified in the instructions;

    Make sure there are no oil leaks from the system;

    By lowering the oil level, check the serviceability of the warning device;

    After launch circulation pump open the circulating water valves at the oil cooler, check the water circulation;

    Check the operation of thermostats;

    Make sure there is sufficient oil overflow from the pressure gravity tank.

    Prepare the turning device for operation;

    Inspect and prepare the shafting;

When preparing the shafting for rotation, you must:

    Check that there are no foreign objects on the shaft line;

    Release the shaft brake;

    If necessary, loosen the stern tube seal;

    Check and prepare the bearing cooling system for operation;

    Check and ensure normal tension of the drive chain to the tachometer sensor;

    Prepare and turn on the turning device;

When turning on the shaft turning device, hang a sign at the control station: TURNING DEVICE ON. To test rotate the TPU turbine unit, it is necessary to obtain permission from the captain's watch officer. Turn the propeller forward and reverse by 1 and 1/3 turns. At the same time, use an ammeter to monitor the power consumed by the electric motor of the turning device and carefully listen to the turbine and gear train. Exceeding the load to the permissible value indicates a malfunction that must be eliminated.

    Prepare the steam line and control system, alarm and protection;

Preparation consists of checking the operation of steam valves for opening and closing in the absence of steam in the steam lines:

    Check whether the steam extraction valves from the turbines are closed;

    Open the purge valves;

    Open and close the quick-closing, shunting and nozzle valves to ensure that they operate properly;

    Carry out an external inspection of pressure reducing and safety valves;

    After supplying oil to the control system, turn off the vacuum relay, open the quick-closing valve, check its operation by turning it off by hand, lowering the oil pressure, and also by acting on the axial shift relay, then leave the valve closed and turn on the vacuum relay;

    Open the purge valves of the receivers, quick-closing and shunting valves, the steam box and the chambers of the nozzle valve rods;

    Before warming up the turbines, warm up and blow through the main steam line to the quick-closing valve through a special warm-up pipeline or by slowly opening the main isolation valves, gradually increasing the pressure in the steam line as it warms up.

    Prepare the condensing system and the main condenser;

for this you need:

    Open the inlet and outlet valves (or valves) of the circulation pump, start the main circulation pump;

    Open the air taps on the water part of the main condenser, closing them after water flows out of them in a continuous stream;

    Check and ensure that the condenser water side and circulation pump drain valves are closed;

    Fill the main condenser condensate collector feed water up to half of the water meter glass;

    Prepare for operation the automatic system for maintaining the condensate level in the condenser;

    Check the opening of the valves on the condensate line supplied to the refrigerators (condensers) of the ejectors;

    Open the valve on the return circulation pipeline;

    Start up the condensate pump, then open the valve on its pressure pipe;

    Check the operation of the condensate level regulator in the condenser.

    Warm up the steam turbines.

Warming up of the turbines begins with the supply of steam to the end seals of the turbines, the main steam jet ejector is prepared and put into operation, thereby raising the vacuum in the condenser. Activate automatic pressure maintenance in the control system.

Raise the vacuum to full to check the density of the system and then reduce it to the value set by the manufacturer.

In the process of raising the vacuum, the turbine rotors are turned using a shaft turning device.

To warm up the turbines of the main turbo-gear units, three heating methods are used:

The first is heating the turbines when the rotor rotates with working steam while parked;

The second is heating the turbines when the rotors are rotated by a shaft turning device;

The third is combined, in which the heating is first carried out when the rotor is rotated by a shaft-turning device, and then, having received permission from the command bridge, test revolutions of the working steam of the turbines are given in forward motion. At the same time, turbines, gears and bearings are carefully listened to.

Check the steam pressure when starting the turbines, which should not exceed the values ​​​​specified in the instructions. Change the direction of rotation of the turbines from forward to reverse using a shunting valve and again listen to all elements of the TPA. After the turbines are warmed up, the circulation condensate and oil pumps are switched to normal operating mode and the vacuum in the main condenser is raised to the operating value.

It should be borne in mind that turbine rotors can remain motionless after steam is supplied to the seals for no more than 5...7 minutes.

    Check the blocking that prevents the unit from being started when the turning gear is turned on.

    Carry out the process of test turning the valve.

When test turning turbo units using a shaft turning device, you must make sure that:

    The quick-closing valve (QCV) is closed;

    Turbine shunting valves are closed;

    The automatic blocking of the turning device, if available, does not allow the UPC to be opened by oil pressure.

During the test rotation of the turbine unit using a shaft turning device, the following actions must be performed:

    Rotate the turbine unit shafts, carefully listening to the turbines and gears;

    Perform a test rotation of at least one revolution of the propeller shaft in forward and reverse;

    Monitor the current strength consumed by the turning device and if the normal value is exceeded or there is a sharp fluctuation in the current, immediately stop the turning device until the causes are determined and the malfunctions are eliminated.

When turning the GTZA VPU, it is possible that the electric motor of the turning device has an increased load or sharp fluctuations when starting and turning the GTZA. This may happen for the following reasons:

    It is possible that there may be contact inside the turbine in the blade or in the seal, or contact in the gear transmission while turning the GTZ, and a characteristic sound can be heard.

In this case, it is necessary to open the necks and listen from the inside, check the axial and radial clearances both in the flow part and in the bearings.

If unacceptable drawdowns or run-ups or defects in the turbine flow path are detected, open the housing or gearbox and eliminate the defects.

    A sound characteristic of the presence of water can be heard in the turbine, water accumulation in the turbine housing, and overflow of the main condenser.

To eliminate them, it is necessary to open the turbine vent, remove water, and bring the level in the main condenser to normal.

    Possible jamming inside the kinematic circuit of the VPU.

In this case, it is necessary to turn off the VPU, check the kinematic diagram and eliminate the jamming.

    The motor may malfunction.

In this case, you need to check the bearings and electrical circuit and eliminate the malfunction.

    The brake is stuck.

    The cable is wound around the screw.

When warming up the turbines, the following procedures are prohibited:

      Reduce the vacuum in the condenser by reducing the supply of steam to the seals;

      Keep the UPC and shunting valves open when turning the GTZ with a turning device.

Once the turbines have warmed up, the following actions must be performed:

    Carry out test runs of the turbine unit from all control stations;

    Make sure the system is working correctly remote control.

During test revolutions of the GTZA, it is possible that the turbine does not start at the permissible value of steam pressure. This is possible for the following reasons:

    Insufficient vacuum in the main condenser;

    Thermal deflection of the turbine rotor as a result of local cooling during parking with a warm gas turbine unit and violation of the cranking mode.

In this case, the turbine installation should be taken out of operation and the turbine should be allowed to cool gradually. For uniform cooling, it is necessary to close the inlet and outlet blades of the main condenser and remove the cooling water from it. After turning the GTZA VPU, put the installation into operation.

    When the nozzle valves open, there is a pressure drop in the main steam line.

In this case, the valves on the main steam line may be faulty or may not be fully open.

The RMC Holding company specializes in the maintenance and repair of steam turbines. The service includes both scheduled and unscheduled maintenance of steam turbine equipment, engineering, turbine operation support, and defect elimination auxiliary installations, as well as repair of components and assemblies, reconstruction and modernization of steam turbine equipment. Our specialists are ready to provide qualified technical support throughout the entire life of the equipment.

Maintenance of steam turbine equipment

Timely maintenance of steam turbines guarantees reliable and uninterrupted operation, as well as high performance.

During the constant operation of turbines, the equipment is subject to moral and physical wear and tear, so periodic maintenance and repair of installations is required.

On average, the service life of steam turbines is 250 thousand hours. In addition, during the operation of equipment, certain defects arise on various components of installations, causing deterioration in the properties of the metal. Creep processes begin, thermal fatigue occurs, and the structure of the material is destroyed. Such changes require urgent decisions to be made to renew the resource and reconstruct the park as a whole.

The more resource hours used, the higher the cost of restoring technical indicators. This is due to an increase in the number of accumulated defects on components and assemblies and a decrease in equipment performance. In order to avoid unnecessary costs, it is necessary to carry out scheduled maintenance of equipment in a timely manner.

Steam turbine modernization

Reconstruction and modernization of steam turbines pursues the following goals:

  • updating the resource of high-temperature components;
  • replacement of parts with components with increased operating parameters;
  • increasing equipment power;
  • increase in efficiency;
  • extension of service life.
  • updating components and assemblies;
  • replacing the SD rotor with a new one;
  • optimization of the drainage system;
  • installation of sealed control diaphragms;
  • improvement of regulatory and protection systems.

The process of modernizing steam turbines is a whole complex of activities that require high professionalism of engineers and the performance of complex and labor-intensive work. The implementation of such projects requires an average of 1-1.5 years from the date of ordering.

The RMC Holding company carries out maintenance and repair of steam turbines, as well as modernization of the turbine fleet both in thermal power plants and in its own workshops. All necessary units, assemblies and various components are delivered to the customer’s site according to the project, all necessary components are developed and presented technical documentation. Our specialists provide control, as well as designer’s supervision in the event of repair work on the territory of the customer's thermal power plant.

By ordering our services, the client receives turbines with an increased service life and significantly improved technical, physical and economic indicators of the equipment.

To order services for maintenance, modernization and reconstruction of steam turbines, you just need to call the phone number listed on the website, or fill out an application online. Our specialists will accept your order and answer all your questions regarding the repair of steam turbines, providing a free consultation. We work not only in Moscow, but also in Krasnodar, Tula, Voronezh and other cities of Russia.

Power plant equipment maintenance and repair system

Reliable supply of energy to consumers is the key to the well-being of any state. This is especially true in our country with harsh climatic conditions, so uninterrupted and reliable operation of power plants is the most important task of energy production.

To solve this problem in the energy sector, maintenance and repair measures were developed that ensured long-term maintenance of equipment in working condition with the best economic performance of its operation and the minimum possible unscheduled stops for repairs. This system is based on carrying out scheduled preventive maintenance (PPR).

  • PPR system is a set of activities for planning, preparing, organizing, monitoring and accounting for various types of maintenance and repair work energy equipment carried out according to a pre-drawn up plan based on a typical volume of repair work, ensuring trouble-free, safe and economical operation of power equipment of enterprises with minimal repair and operating costs. Essence PPR systems is that after a predetermined operating time, the equipment’s need for repairs is satisfied in a planned manner, by carrying out scheduled inspections, tests and repairs, the rotation and frequency of which are determined by the purpose of the equipment, the requirements for its safety and reliability, design features, maintainability and operating conditions.

The PPR system is built in such a way that each previous event is preventive in relation to the next one. A distinction is made between equipment maintenance and repair.

  • Maintenance- a set of operations to maintain the functionality or serviceability of a product when used for its intended purpose. It provides for the care of equipment: inspections, systematic monitoring of good condition, monitoring operating modes, compliance with operating rules, manufacturer's instructions and local operating instructions, eliminating minor faults that do not require shutting down the equipment, adjustments, and so on. Maintenance of existing power plant equipment includes the implementation of a set of measures for inspection, control, lubrication, and adjustment, which do not require the equipment to be taken out for routine repairs.

Maintenance (inspections, checks and tests, adjustment, lubrication, washing, cleaning) makes it possible to increase the warranty period of equipment before the next routine repair, and to reduce the amount of routine repairs.

  • Repair- a set of operations to restore the serviceability or performance of products and restore the resources of products or their components. Performing routine maintenance, in turn, prevents the need to schedule more frequent major repairs. Such organization of planned repairs and operations Maintenance makes it possible to constantly maintain equipment in trouble-free condition at minimal cost and without additional unplanned downtime for repairs.

Along with increasing the reliability and security of power supply, the most important task of repair maintenance is to improve or, in extreme cases, stabilize the technical and economic indicators of equipment. As a rule, this is achieved by stopping the equipment and opening its basic elements (boiler furnaces and convective heating surfaces, flow parts and turbine bearings).

It should be noted that the problems of reliability and efficiency of operation of thermal power plant equipment are so interconnected that it is difficult to separate them from one another.

For turbine equipment during operation, first of all, the technical and economic condition of the flow path is monitored, including:

  • - salt deposits on the blades and nozzles, which cannot be eliminated by washing under load or at idle (silicon oxide, iron, calcium, magnesium, etc.); There are cases where, as a result of skidding, turbine power decreased by 25% in 10...15 days.
  • - an increase in gaps in the flow part leads to a decrease in efficiency, for example - an increase in the radial gap in seals from 0.4 to 0.6 mm causes an increase in steam leakage by 50%.

It should be noted that an increase in gaps in the flow passage, as a rule, does not occur during normal operation, but during starting operations, when working with increased vibration, rotor deflections, and unsatisfactory thermal expansion of cylinder bodies.

During repairs, an important role is played by pressure testing and elimination of air suction points, as well as the use of various progressive seal designs in rotating air heaters. Repair personnel must, together with operating personnel, monitor air suction and, if possible, ensure their elimination not only during repairs, but also on operating equipment. Thus, a decrease (deterioration) in vacuum by 1% for a 500 MW power unit leads to excessive fuel consumption by approximately 2 tons. t./h, which is 14 thousand t.e. t/year, or in 2001 prices 10 million rubles.

The efficiency indicators of the turbine, boiler and auxiliary equipment are usually determined by conducting rapid tests. The purpose of these tests is not only to assess the quality of repairs, but also to regularly monitor the operation of equipment during the overhaul period. Analysis of the test results allows you to reasonably judge whether the unit should be stopped (or, if possible, individual elements of the installation should be switched off). When making decisions, the possible costs of shutdown and subsequent start-up, restoration work, possible undersupply of electricity and heat are compared with losses caused by the operation of equipment with reduced efficiency. Express tests also determine the time during which operation of equipment with reduced efficiency is allowed.

In general, equipment maintenance and repair involve the implementation of a set of works aimed at ensuring the good condition of the equipment, its reliable and economical operation, carried out with a certain frequency and consistency.

  • Repair cycle- the smallest repeating intervals of time or operating time of a product, during which all established types of repairs are carried out in a certain sequence in accordance with the requirements of regulatory and technical documentation (operating time of power equipment, expressed in years of calendar time between two planned overhauls, and for newly introduced equipment - operating time from commissioning to the first planned overhaul).
  • Repair cycle structure defines the sequence various types repair and maintenance work on equipment within one repair cycle.

All equipment repairs are divided (classified) into several types depending on the degree of preparedness, the volume of work performed and the method of performing repairs.

  • Unscheduled repairs- repairs carried out without prior appointment. Unscheduled repairs are carried out when equipment defects occur that lead to failures.
  • Scheduled repairs - repairs, which are carried out in accordance with the requirements of normative and technical documentation (NTD). Planned repairs of equipment are based on the study and analysis of the service life of parts and assemblies with the establishment of technically and economically sound standards.

Scheduled repairs of a steam turbine are divided into three main types: major, medium and current.

  • Major renovation- repairs performed to restore serviceability and restore full or close to full service life of equipment with the replacement or restoration of any of its parts, including basic ones.

Overhaul is the most voluminous and complex type of repair; when it is performed, all bearings, all cylinders are opened, the shaft line and flow part of the turbine are disassembled. If major repairs are carried out in accordance with standard technological process, then it is called standard overhaul. If major repairs are carried out by means other than standard ones, then such repairs are classified as specialized repairs with the name of the derivative type from a standard overhaul.

If major standard or major specialized repairs are performed on a steam turbine that has been in operation for more than 50 thousand hours, then such repairs are divided into three categories of complexity; the most complex repairs are in the third category. Categorization of repairs is usually applied to turbines of power units with a capacity of 150 to 800 MW.

Categorizing repairs by degree of complexity is aimed at compensating for labor and financial costs due to wear and tear of turbine parts and the formation of new defects in them, along with those that appear during each repair.

  • Maintenance- repairs performed to ensure or restore the operability of equipment, and consisting of the replacement and (or) restoration of individual parts.

Current repairs of a steam turbine are the least voluminous; when performing it, bearings may be opened or one or two control valves may be disassembled, and the automatic shutter valve may be opened. For block turbines, current repairs are divided into two categories of complexity: first and second (the most complex repairs have the second category).

  • Medium renovation- repairs carried out to the extent established in the technical documentation to restore serviceability and partially restore the service life of equipment with the replacement or restoration of individual components and their control technical condition.

The average repair of a steam turbine differs from capital and current repairs in that its range partially includes the volumes of both capital and current repairs. When performing a medium repair, one of the turbine cylinders may be opened and the shaft line of the turbine unit may be partially disassembled; the stop valve may also be opened and partial repairs of the control valves and flow parts of the opened cylinder may be performed.

All types of repairs have the following characteristics in common: cyclicality, duration, volumes, financial costs.

  • Cyclicality- this is the frequency of carrying out one or another type of repair on a scale of years, for example, no more than 5...6 years should pass between the next and previous major repairs, no more than 3 years should pass between the next and previous medium repairs, between the next and previous current repairs no more than 2 years should pass. Increasing the cycle time between repairs is desirable, but in some cases this leads to a significant increase in the number of defects.
  • Duration repairs for each main type based on standard work is directive and approved by the “Rules for organizing maintenance and repair of equipment, buildings and structures of power plants and networks”. The duration of repairs is determined as a value on the scale of calendar days, for example, for steam turbines, depending on the power, a typical overhaul ranges from 35 to 90 days, an average from 18 to 36 days, an ongoing one from 8 to 12 days.

Important issues are the duration of repairs and its financing. The duration of turbine repair is a serious problem, especially when the expected volume of work is not confirmed by the condition of the turbine or when additional work arises, the duration of which can reach 30...50% of the guideline.

  • Volume of work are also defined as a standard set of technological operations, the total duration of which corresponds to the directive duration of the type of repair; in the Rules this is called “the nomenclature and scope of work during a major (or other type) repair of a turbine” and then there is a list of the names of the work and the elements to which they are aimed.

Derivative names of repairs from all main types of repairs differ in the volume and duration of work. The most unpredictable in terms of volume and timing are emergency repairs; they are characterized by such factors as the suddenness of an emergency shutdown, the unavailability of material, technical and labor resources for repairs, the uncertainty of the reasons for the failure and the volume of defects that caused the shutdown of the turbine unit.

When performing repair work, various methods can be used, including:

  • aggregate repair method- an impersonal repair method, in which faulty units are replaced with new or pre-repaired ones;
  • factory repair method- repair of transportable equipment or its individual components at repair plants based on the use of advanced technologies and developed specialization.

Equipment repair is carried out in accordance with the requirements of regulatory, technical and technological documentation, which include current industry standards, technical specifications for repairs, repair manuals, operating instructions, guidelines, norms, rules, instructions, performance characteristics, repair drawings and more.

On modern stage development of the electric power industry, characterized by low rates of renewal of fixed production assets, increases the priority of equipment repair and the need to develop a new approach to financing repairs and technical re-equipment.

The reduction in the use of installed capacity of power plants has led to additional wear and tear on equipment and an increase in the share of the repair component in the cost of energy generated. The problem of maintaining the efficiency of energy supply has increased, in the solution of which the leading role belongs to the repair industry.

The existing energy repair production, previously based on scheduled preventive maintenance with regulation of repair cycles, has ceased to meet economic interests. The previously existing PPR system was formed to carry out repairs in conditions of a minimum reserve of energy capacity. Currently, there has been a decrease in the annual operating time of equipment and an increase in the duration of its downtime.

In order to reform the current maintenance and repair system, it was proposed to change the maintenance and repair system and switch to a repair cycle with an assigned time between repairs by type of equipment. The new maintenance and repair system (STOIR) allows you to increase the calendar duration of the overhaul campaign and reduce average annual repair costs. According to the new system assigned overhaul life between major overhauls is taken to be equal to the base value of the total operating time for the repair cycle in the base period and is the standard.

Taking into account the current regulations at power plants, standards for time between repairs have been developed for the main equipment of power plants. The change in the PPR system is due to changed operating conditions.

Both equipment maintenance systems provide for three types of repairs: major, medium and current. These three types of repairs make up unified system maintenance aimed at maintaining equipment in working condition, ensuring its reliability and the required efficiency. The duration of equipment downtime for all types of repairs is strictly regulated. The issue of increasing the duration of equipment downtime for repairs when it is necessary to perform above-standard work is considered individually each time.

In many countries, a “condition-based” repair system for power equipment is used, which can significantly reduce the cost of repair maintenance. But this system involves the use of techniques and hardware that make it possible to monitor the current technical condition of the equipment with the necessary frequency (and for a number of parameters continuously).

Various organizations in the USSR, and later in Russia, developed systems for monitoring and diagnosing the condition of individual turbine components, and attempts were made to create complex diagnostic systems for powerful turbine units. These works require significant financial costs, but, based on the experience of operating similar systems abroad, they quickly pay off.

V. N. Rodin, A. G. Sharapov, B. E. Murmansky, Yu. A. Sakhnin, V. V. Lebedev, M. A: Kadnikov, L. A. Zhuchenko

Training manual "Repair of steam turbines"

General information. Marine vessels operate main and auxiliary steam turbo mechanisms (turbogenerators, turbopumps, turbofans); all of them undergo annual inspections, during which the following is carried out: external inspection, readiness for action, operation in action, serviceability of maneuvering and starting devices and remote control devices, and also checking the serviceability of mounted and driving mechanisms.
Maintenance of a steam turbine includes carrying out scheduled preventive inspections (PPO) and repairs (SPR), adjusting and tuning turbine elements, troubleshooting, checking equipment for compliance with technical specifications, restoring lost properties, as well as taking measures to preserve turbines when they are inactive.
Depending on the volume and nature of the work performed, maintenance is divided into daily, monthly and annual.
Daily maintenance includes the following basic operations:
- visual inspection;
- removal of fuel, oil and water leaks;
- removal of traces of corrosion;
- vibration measurement.
Dismantling and dismantling of turbines. According to the manufacturer's instructions, scheduled openings of turbines are carried out. The purpose of opening turbines is to assess the technical condition of parts and clean the flow path from corrosion, soot and scale.
Disassembly of the turbine begins no earlier than 8-12 hours after it is stopped, that is, after cooling, when the temperature of the housing walls becomes equal to the ambient air temperature (about 20 C).
If the turbine is dismantled for transportation to the workshop, then the following dismantling procedure is observed:
- disconnect the turbine from the incoming steam;
- drain or pump out water from the condenser;
- pump oil out of the turbine or drain it, freeing the oil system;
- remove fittings and instrumentation;
- disconnect pipelines directly connected to the turbine or that interfere with its dismantling from the foundation;
- remove the turbine casing and insulation;
- dismantle handrails, remove platforms and shields;
- remove the quick-closing valve of the receiver and bypass valves;
- disconnect the turbine rotor from the gearbox;
- insert the slings and secure them to the lifting device;
- release the foundation bolts and remove the turbine from the foundation. The stator cover is undermined using squeezing bolts, and the lifting
(lowering) it and the rotor are carried out with a special device. This device consists of four screw columns and lifting mechanisms. Rulers are attached to the screw columns to control the lifting height of the stator cover or turbine rotor. When lifting the lid or rotor, stop every 100-150 mm and check the uniformity of their lifting. The same is done when lowering them.
Flaw detection and repair. Flaw detection of the turbine is carried out in two stages: before opening and after opening during disassembly. Before opening the turbine, the following are measured using standard instrumentation: axial run-up of the rotor in the thrust bearing, oil clearances in the bearings, clearances in the limiting speed controller.
Typical defects of a steam turbine include: deformation of the stator connector flanges, cracks and corrosion of the internal cavities of the stator; deformation and imbalance of the rotor; deformation of the working disks (weakening of their fit on the rotor shaft), cracks in the area of ​​the keyways; erosive wear, mechanical and fatigue destruction of rotor blades; diaphragm deformation; erosive wear and mechanical damage to the nozzle apparatus and guide vanes; wear of rings of end and intermediate seals, bearings.
During turbine operation, thermal deformations of parts mainly occur due to violations of the Technical Operation Rules.
Thermal deformations arise as a result of uneven heating of the turbine during its preparation for start-up and during shutdown.
The operation of an unbalanced rotor causes vibration of the turbine, which can lead to breakage of the blades and bandage, and destruction of seals and bearings.
Steam turbine housing performed with a horizontal connector, which divides it into two halves. The lower half is the body, and the upper half is the lid.
The repair consists of restoring the density of the housing connector plane due to warping. Warping of the parting plane with gaps up to 0.15 mm is eliminated by scraping. After scraping is completed, the cover is put back in place and the presence of local gaps, which should not be more than 0.05 mm, is checked with a feeler gauge. Cracks, fistulas and corrosion pits in the turbine housing are cut and eliminated by welding and surfacing.
Steam turbine rotors. In main turbines, the rotors are most often made solid forged, while in auxiliary turbines the rotor is usually assembled, consisting of a shaft and a turbine impeller.
Rotor deformation (bending), which does not exceed 0.2 mm, is removed by mechanical processing, up to 0.4 mm - by thermal straightening, and above 0.4 mm - by thermomechanical straightening.
A rotor with cracks is replaced. Wear on the journals is eliminated by grinding. Ovality and conicality of the necks is allowed no more than 0.02 mm.
Working disks. Disks with cracks are replaced. The deformation of the disks is detected by the end runout and, if it does not exceed 0.2 mm, it is eliminated by turning the end of the disk on a machine. If the deformation is greater, the discs are subjected to mechanical straightening or replacement. Weakening of the disk fit on the shaft is eliminated by chrome-plating its mounting hole.
Disc blades. Erosive wear is possible on the blades and, if it does not exceed 0.5-1.0 mm, then they are filed down and ground by hand. In case of major damage, the blades are replaced. New blades are manufactured at turbine manufacturing plants. Before installing new blades, they are weighed.
If there is mechanical damage and separation of the band band of the working blades, it is replaced, for which the old band is removed.
Turbine diaphragms. Any diaphragm consists of two halves: upper and lower. The upper half of the diaphragm is installed in the housing cover, and the lower half is installed in the lower half of the turbine housing. The repair involves eliminating warping of the diaphragm. The warpage of the diaphragm is determined on the plate using the probe plates; for this, the diaphragm is placed with the rim on the side of the steam outlet on the plate and the presence of gaps between the rim and the plate is checked with a probe.
Warping is eliminated by grinding or scraping the end of the rim on the slab for paint. Then, along the scraped end of the diaphragm rim, a landing groove is scraped in the turbine housing on the side of the steam outlet. This is done to achieve a tight fit of the diaphragm to the body, in order to reduce steam leaks. If there are cracks on the diaphragm rim, replace it.
Labyrinth (end) seals. By design, labyrinth seals can be of a simple type, an elastic herringbone type, or an elastic comb type. When repairing seals, bushings and segments of labyrinth seals with damage are replaced, setting radial and axial clearances in accordance with the repair specifications.
Support bearings in turbines there may be slipping and rolling. In the main ships steam turbines use plain bearings. Repairing such bearings is similar to repairing diesel bearings. The size of the installation oil gap depends on the diameter of the rotor shaft journal. With a shaft journal diameter of up to 125 mm, the installation gap is 0.12-0.25 mm, and the maximum permissible is 0.18-0.35 mm. Rolling bearings (ball, roller) are installed in turbines of auxiliary mechanisms and they cannot be repaired.
Static balancing of discs and rotors. One of the reasons that causes vibration in a turbine is the imbalance of the rotating rotor and disks. Rotating parts may have one or more unbalanced masses. Depending on their location, static or dynamic imbalance of masses is possible. Static imbalance can be determined statically, without rotating the part. Static balancing is the alignment of the center of gravity with its geometric axis of rotation. This is achieved by removing metal from the heavy part of the part or adding it to its light part. Before balancing, check the radial runout of the rotor, which should be no more than 0.02 mm. Static balancing of parts operating at a rotation speed of up to 1000 min-1 is carried out in one stage, and at a higher rotation speed - in two stages.
At the first stage, the part is balanced to its indifferent state, in which it stops in any position. This is achieved by determining the position of the heavy point, and then selecting and attaching a balancing weight on the opposite side.
After balancing the part, a permanent load is attached to its light side instead of a temporary load, or the corresponding amount of metal is removed from the heavy side and the balancing is completed.
The second stage of balancing is to eliminate the residual imbalance (imbalance) remaining due to the inertia of the part and the presence of friction between them and the supports. To do this, the surface of the end of the part is divided into six to eight equal parts. Then, the part with the temporary load is installed so that it is in the horizontal plane (point 1). At this point, the mass of the temporary load is increased until the part comes out of equilibrium and begins to rotate. After this operation, the load is removed and weighed on scales. Work is performed in the same sequence for the remaining points of the part. Based on the data obtained, a curve is constructed, which, if balancing is performed accurately, should have the shape of a sinusoid. The maximum and minimum points are found on this curve. The maximum point of the curve corresponds to the light part of the part, and the minimum point corresponds to the difficult part. The accuracy of static balancing is estimated by the inequality:

Where TO— mass of the balancing load, g;
R— radius of temporary load installation, mm;
G— rotor mass, kg;
Lst— maximum permissible displacement of the center of gravity of the part from its axis of rotation, µm. The maximum permissible displacement of the center of gravity of a part is found from the diagram of the maximum permissible displacement of the center of gravity during static balancing, from the turbine’s passport data, or from the formula:


Where n— rotor rotation speed, s-1.
Dynamic balancing. During dynamic balancing, all rotor masses are reduced to two masses lying in the same diametrical plane, but on different sides of the axis of rotation. Dynamic imbalance can only be determined by the centrifugal forces that arise when the part rotates at a sufficient speed. The quality of dynamic balancing is assessed by the amplitude of rotor oscillations at the critical speed of its rotation. Balancing is carried out on a special stand in the factory. The stand has pendulum or swing type supports (stand types 9B725, 9A736, MS901, DB 10, etc.). The turbine rotor is placed on two spring bearings mounted on the frame supports and connected to the electric motor. By rotating the turbine rotor with an electric motor, its critical rotation speed is determined, while measuring in turn the maximum amplitudes of vibration of the rotor journals on each side. Then, each side of the rotor is marked around the circumference into 6-8 equal parts and the mass of the test load for each side is calculated. Balancing begins on the side of the bearing that has a large vibration amplitude. The second bearing is secured. The test weight is attached at point 1 and the maximum amplitude of oscillation of the rotor neck is measured at the critical frequency of its rotation. Then the load is removed, secured at point 2 and the operation is repeated. Based on the data obtained, a graph is constructed from which the maximum and minimum amplitudes and the average value of the amplitude are determined, and based on its value, the mass of the balancing load is determined. The bearing with a larger vibration amplitude is fixed, and the second one is released from the fastening. The balancing operation of the second side is repeated in the same sequence. The balancing results are assessed using the following inequality:


Where aoct— amplitude of oscillations of the rotor ends, mm;
R— radius of balancing weight attachment, mm;
G— part of the rotor mass attributable to this support, kg;
Lct— permissible displacement of the center of gravity from the axis of rotation of the rotor during dynamic balancing, µm.
Turbine assembly includes alignment of the rotor and diaphragms.
Rotor alignment. Before centering the rotor, the sliding bearings are adjusted to the beds and journals of the rotor. Then the rotor is aligned relative to the axis of the bore under the turbine end seal races. When aligning the rotor and diaphragms, a false shaft (process shaft) is used, which is placed on bearings. Then the gaps between the shaft journal and the cylindrical surface under the seals are measured in the vertical and horizontal planes. The permissible displacement of the rotor axis relative to the axis of the bores for the seals is allowed up to 0.05 mm. Equality of the gaps indicates good alignment, and if not, then the rotor axis is aligned.
Closing the turbine. Before laying the rotor, its journals and bearings are lubricated with clean oil. The rotor is then placed on the bearings and the cover is lowered. After crimping the cover, the ease of rotation of the rotor is checked. To seal the parting surfaces of a turbine operating at pressures above 3.5 MPa and temperatures up to 420 C, “Sealant” paste or other mastics are used. In this case, the threads of nuts, studs and simple bolts are coated with a thin layer of graphite, and the tight-fitting bolts are lubricated with mercury ointment.
Testing turbines after repair. Repaired turbo mechanisms must first be tested at the SRZ stand, then mooring and sea trials must be carried out. In the absence of stands at the shipyard, turbo mechanisms are subjected only to mooring and sea trials. Mooring tests consist of running-in, adjustment and testing of turbo mechanisms according to a bench test program.
All preparations for the test start-up of the turbine installation (checking the operation of the valves, warming up the turbine and steam lines, lubrication system, etc.) are carried out in full accordance with the “Rules for the maintenance and care of ship steam turbines.” In addition, the lubrication system and bearings are pumped with hot oil at a temperature of 40-50 C using a lubrication pump. To clean the lubrication system from contaminants, temporary filters made of copper mesh and gauze, etc. are installed in front of the bearings. They are periodically opened, washed and put back in place. Pump the oil until there is no sediment on the filters. After pumping, the oil is drained from the supply tank, the tank is cleaned and filled with fresh oil.
Before starting, the turbine is turned with a shaft turning device, and the locations of the turbine and gearbox bearings, the area of ​​the flow path, seals and gears are carefully listened with a stethoscope. If there are no comments, the turbine rotor is rotated with steam, bringing its rotation to a frequency of 30-50 min -1, and the steam is immediately shut off. The secondary start of the turbine is carried out if no malfunctions are detected during cranking.
If there is any extraneous sound in the turbine, it is immediately stopped, inspected, the causes of malfunctions are identified and measures are taken to eliminate them.
The operation of the turbo mechanism at idle is checked with a gradual increase in the turbine rotor speed to the nominal value and at the same time the operation of the speed controller, quick-closing valve, vacuum condenser, etc.
During sea trials, the technical and economic indicators of the turbo mechanism are determined in all operating modes.

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