Rules for testing head steam turbines for ships. Abstract: Thermal tests of steam turbines and turbine equipment. Efficiency of the regeneration system and network heaters
Thermal testing of steam turbines
and turbine equipment
In recent years, in the area of energy conservation, attention to fuel consumption standards for enterprises generating heat and electricity has increased, therefore, for generating enterprises, actual indicators of the efficiency of heat and power equipment are becoming important.
At the same time, it is known that actual efficiency indicators under operating conditions differ from the calculated (factory) ones, therefore, in order to objectively normalize fuel consumption for the production of heat and electricity, it is advisable to test equipment.
Based on equipment testing materials, standard energy characteristics and a model (procedure, algorithm) for calculating specific fuel consumption rates are developed in accordance with RD 34.09.155-93 “Guidelines for the compilation and content of energy characteristics of thermal power plant equipment” and RD 153-34.0-09.154 -99 “Regulations on the regulation of fuel consumption at power plants.”
Testing of thermal power equipment is of particular importance for facilities operating equipment put into operation before the 70s and where boilers, turbines, and auxiliary equipment were modernized and reconstructed. Without testing, rationing fuel consumption according to calculated data will lead to significant errors not in favor of generating enterprises. Therefore, the costs of thermal testing are insignificant compared to the benefits from them.
The objectives of thermal testing of steam turbines and turbine equipment:
|
|
The objectives of express testing of steam turbines are:
|
Modern technologies and the level of engineering knowledge make it possible to economically modernize units, improve their performance and increase their service life.
The main goals of modernization are:
- reduction of power consumption of the compressor unit;
- increasing compressor performance;
- increasing the power and efficiency of the process turbine;
- reduction of natural gas consumption;
- increasing the operational stability of equipment;
- reducing the number of parts by increasing the pressure of compressors and operating turbines on fewer stages while maintaining and even increasing the efficiency of the power plant.
Improvement of the given energy and economic indicators of the turbine unit is carried out through the use of modernized design methods (solving direct and inverse problems). They are connected:
- with the inclusion of more correct models of turbulent viscosity in the calculation scheme,
- taking into account the profile and end obstruction by the boundary layer,
- elimination of separation phenomena with an increase in the diffusivity of the interscapular channels and a change in the degree of reactivity (pronounced unsteadiness of the flow before the surge occurs),
- the ability to identify an object using mathematical models with genetic optimization of parameters.
The ultimate goal of modernization is always to increase production of the final product and minimize costs.
An integrated approach to the modernization of turbine equipment
When carrying out modernization, Astronit usually uses an integrated approach, in which the following components of the technological turbine unit are reconstructed (modernized):
- compressor;
- turbine;
- supports;
- centrifugal compressor-supercharger;
- intercoolers;
- animator;
- Lubrication system;
- air purification system;
- automatic control and protection system.
Modernization of compressor equipment
The main areas of modernization practiced by Astronit specialists:
- replacement of flow parts with new ones (so-called replaceable flow parts, including impellers and blade diffusers), with improved characteristics, but within the dimensions of existing housings;
- reducing the number of stages by improving the flow part based on three-dimensional analysis in modern software products;
- application of easy-to-work coatings and reduction of radial clearances;
- replacing seals with more efficient ones;
- replacement of compressor oil bearings with “dry” bearings using magnetic suspension. This allows you to eliminate the use of oil and improve the operating conditions of the compressor.
Implementation of modern control and protection systems
To increase operational reliability and efficiency, modern instrumentation, digital automatic control and protection systems (both individual parts and the entire technological complex as a whole), diagnostic systems and communication systems are being introduced.
- STEAM TURBINES
- Nozzles and blades.
- Thermal cycles.
- Rankine cycle.
- Turbine designs.
- Application.
- OTHER TURBINES
- Hydraulic turbines.
- Gas turbines.
Scroll up Scroll down
Also on topic
- AIRCRAFT POWER PLANT
- ELECTRIC ENERGY
- SHIP POWER PLANTS AND PROPULSIONS
- HYDROPOWER
TURBINE
TURBINE, a prime mover with rotational movement of the working element to convert the kinetic energy of the flow of a liquid or gaseous working fluid into mechanical energy on the shaft. The turbine consists of a rotor with blades (bladed impeller) and a housing with branch pipes. The pipes supply and discharge the flow of the working fluid. Turbines, depending on the working fluid used, are hydraulic, steam and gas. Depending on the average direction of flow through the turbine, they are divided into axial, in which the flow is parallel to the axis of the turbine, and radial, in which the flow is directed from the periphery to the center.
STEAM TURBINES
The main elements of a steam turbine are the casing, nozzles and rotor blades. Steam from an external source is supplied to the turbine through pipelines. In the nozzles, the potential energy of the steam is converted into the kinetic energy of the jet. The steam escaping from the nozzles is directed to curved (specially profiled) working blades located along the periphery of the rotor. Under the action of a jet of steam, a tangential (circumferential) force appears, causing the rotor to rotate.
Nozzles and blades.
Steam under pressure enters one or more stationary nozzles, in which it expands and from where it flows out at high speed. The flow exits the nozzles at an angle to the plane of rotation of the rotor blades. In some designs, the nozzles are formed by a series of fixed blades (nozzle apparatus). The impeller blades are curved in the direction of flow and arranged radially. In an active turbine (Fig. 1, A) the flow channel of the impeller has a constant cross-section, i.e. the speed in relative motion in the impeller does not change in absolute value. The steam pressure in front of and behind the impeller is the same. In a jet turbine (Fig. 1, b) the flow channels of the impeller have a variable cross-section. The flow channels of a jet turbine are designed so that the flow rate in them increases and the pressure drops accordingly.
R1; c – blading of the impeller. V1 – steam velocity at the nozzle exit; V2 – steam velocity behind the impeller in a fixed coordinate system; U1 – peripheral speed of the blade; R1 – steam velocity at the entrance to the impeller in relative motion; R2 – steam velocity at the exit from the impeller in relative motion. 1 – bandage; 2 – shoulder blade; 3 – rotor." title="Fig. 1. TURBINE WORKING BLADES. a – active impeller, R1 = R2; b – reactive impeller, R2 > R1; c – impeller blade. V1 – steam speed at the exit from the nozzle; V2 – steam velocity behind the impeller in a fixed coordinate system; U1 – peripheral speed of the blade; R1 – steam velocity at the entrance to the impeller in relative motion; R2 – steam velocity at the exit from the impeller in relative motion. 1 – bandage; 2 – blade; 3 – rotor.">Рис. 1. РАБОЧИЕ ЛОПАТКИ ТУРБИНЫ. а – активное рабочее колесо, R1 = R2; б – реактивное рабочее колесо, R2 > R1; в – облопачивание рабочего колеса. V1 – скорость пара на выходе из сопла; V2 – скорость пара за рабочим колесом в неподвижной системе координат; U1 – окружная скорость лопатки; R1 – скорость пара на входе в рабочее колесо в относительном движении; R2 – скорость пара на выходе из рабочего колеса в относительном движении. 1 – бандаж; 2 – лопатка; 3 – ротор.!}
Turbines are usually designed to be on the same shaft as the device that consumes their power. The rotation speed of the impeller is limited by the strength of the materials from which the disk and blades are made. For the most complete and efficient conversion of steam energy, turbines are made multi-stage.
Thermal cycles.
Rankine cycle.
Into a turbine operating according to the Rankine cycle (Fig. 2, A), steam comes from an external steam source; There is no additional heating of steam between turbine stages, there are only natural heat losses.
Reheat cycle.
In this cycle (Fig. 2, b) steam after the first stages is sent to the heat exchanger for additional heating (superheating). It then returns to the turbine, where its final expansion occurs in subsequent stages. Increasing the temperature of the working fluid makes it possible to increase the efficiency of the turbine.
Rice. 2. TURBINES WITH DIFFERENT THERMAL CYCLES. a – simple Rankine cycle; b – cycle with intermediate heating of steam; c – cycle with intermediate steam extraction and heat recovery.
A cycle with intermediate selection and recovery of waste steam heat.
The steam leaving the turbine still has significant thermal energy, which is usually dissipated in the condenser. Some of the energy can be recovered by condensing the exhaust steam. Some of the steam can be selected at the intermediate stages of the turbine (Fig. 2, V) and is used for preheating, for example, feed water or for any technological processes.
Turbine designs.
The working fluid expands in the turbine, therefore, in order to pass the increased volume flow, the last stages (low pressure) must have a larger diameter. The increase in diameter is limited by the permissible maximum stresses caused by centrifugal loads at elevated temperatures. In split-flow turbines (Figure 3), the steam passes through different turbines or different turbine stages.
Rice. 3. TURBINES WITH BRANCHING FLOW. a – twin parallel turbine; b – twin turbine of parallel action with oppositely directed flows; c – turbine with flow branching after several high-pressure stages; d – compound turbine.
Application.
To ensure high efficiency, the turbine must rotate at high speed, but the number of revolutions is limited by the strength of the turbine materials and the equipment that is located on the same shaft with it. Electric generators at thermal power plants are designed for 1800 or 3600 rpm and are usually installed on the same shaft as the turbine. Centrifugal blowers and pumps, fans and centrifuges can be installed on the same shaft with the turbine.
Low-speed equipment is coupled to a high-speed turbine through a reduction gearbox, such as in marine engines where the propeller must rotate at 60 to 400 rpm.
OTHER TURBINES
Hydraulic turbines.
In modern hydraulic turbines, the impeller rotates in a special casing with a scroll (radial turbine) or has a guide vane at the inlet that provides the desired direction of flow. The corresponding equipment (an electric generator at a hydroelectric power station) is usually installed on the shaft of a hydraulic turbine.
Gas turbines.
A gas turbine uses energy from combustion gases from an external source. Gas turbines are similar in design and operating principle to steam turbines and are widely used in technology. see also AIRCRAFT POWER PLANT; ELECTRIC ENERGY; SHIP POWER INSTALLATIONS AND PROPULSIONS; HYDROPOWER.
Literature
Uvarov V.V. Gas turbines and gas turbine plants. M., 1970
Verete A.G., Delving A.K. Marine steam power plants and gas turbines. M., 1982
Trubilov M.A. and etc. Steam and gas turbines. M., 1985
Sarantsev K.B. and etc. Atlas of turbine stages. L., 1986
Gostelow J. Aerodynamics of turbomachinery grilles. M., 1987
Thermal testing of steam turbines
and turbine equipment
In recent years, in the area of energy conservation, attention to fuel consumption standards for enterprises generating heat and electricity has increased, therefore, for generating enterprises, actual indicators of the efficiency of heat and power equipment are becoming important.
At the same time, it is known that actual efficiency indicators under operating conditions differ from the calculated (factory) ones, therefore, in order to objectively normalize fuel consumption for the production of heat and electricity, it is advisable to test equipment.
Based on equipment testing materials, standard energy characteristics and a model (procedure, algorithm) for calculating specific fuel consumption rates are developed in accordance with RD 34.09.155-93 “Guidelines for the compilation and content of energy characteristics of thermal power plant equipment” and RD 153-34.0-09.154 -99 “Regulations on the regulation of fuel consumption at power plants.”
Testing of thermal power equipment is of particular importance for facilities operating equipment put into operation before the 70s and where boilers, turbines, and auxiliary equipment were modernized and reconstructed. Without testing, rationing fuel consumption according to calculated data will lead to significant errors not in favor of generating enterprises. Therefore, the costs of thermal testing are insignificant compared to the benefits from them.
|
The objectives of thermal testing of steam turbines and turbine equipment: determination of actual efficiency; obtaining thermal characteristics; comparison with manufacturer's warranties; obtaining data for standardizing, monitoring, analyzing and optimizing the operation of turbine equipment; obtaining materials for developing energy characteristics; development of measures to improve efficiency |
|
|
The objectives of express testing of steam turbines are: determining the feasibility and scope of repairs; assessment of the quality and effectiveness of repairs or modernization; assessment of the current change in turbine efficiency during operation. |
Modern technologies and the level of engineering knowledge make it possible to economically modernize units, improve their performance and increase their service life.
The main goals of modernization are:
reduction of power consumption of the compressor unit;
increasing compressor performance;
increasing the power and efficiency of the process turbine;
reduction of natural gas consumption;
increasing the operational stability of equipment;
reducing the number of parts by increasing the pressure of compressors and operating turbines on fewer stages while maintaining and even increasing the efficiency of the power plant.
Improvement of the given energy and economic indicators of the turbine unit is carried out through the use of modernized design methods (solving direct and inverse problems). They are connected:
with the inclusion of more correct models of turbulent viscosity in the calculation scheme,
taking into account the profile and end obstruction by the boundary layer,
elimination of separation phenomena with an increase in the diffusivity of the interscapular channels and a change in the degree of reactivity (pronounced unsteadiness of the flow before the surge occurs),
the ability to identify an object using mathematical models with genetic optimization of parameters.
The ultimate goal of modernization is always to increase production of the final product and minimize costs.
An integrated approach to the modernization of turbine equipment
When carrying out modernization, Astronit usually uses an integrated approach, in which the following components of the technological turbine unit are reconstructed (modernized):
centrifugal compressor-supercharger;
intercoolers;
animator;
Lubrication system;
air purification system;
automatic control and protection system.
compressor;
Modernization of compressor equipment
The main areas of modernization practiced by Astronit specialists:
replacement of flow parts with new ones (so-called replaceable flow parts, including impellers and blade diffusers), with improved characteristics, but within the dimensions of existing housings;
reducing the number of stages by improving the flow part based on three-dimensional analysis in modern software products;
application of easy-to-work coatings and reduction of radial clearances;
replacing seals with more efficient ones;
replacement of compressor oil bearings with “dry” bearings using magnetic suspension. This allows you to eliminate the use of oil and improve the operating conditions of the compressor.
Implementation of modern control and protection systems
To increase operational reliability and efficiency, modern instrumentation, digital automatic control and protection systems (both individual parts and the entire technological complex as a whole), diagnostic systems and communication systems are being introduced.
STEAM TURBINES
Nozzles and blades.
Thermal cycles.
Rankine cycle.
Reheat cycle.
A cycle with intermediate selection and recovery of waste steam heat.
Turbine designs.
Application.
OTHER TURBINES
Hydraulic turbines.
Gas turbines.
Scroll up Scroll down
Also on topic
AIRCRAFT POWER PLANT
ELECTRIC ENERGY
SHIP POWER PLANTS AND PROPULSIONS
HYDROPOWER
TURBINE
TURBINE, a prime mover with rotational movement of the working element to convert the kinetic energy of the flow of a liquid or gaseous working fluid into mechanical energy on the shaft. The turbine consists of a rotor with blades (bladed impeller) and a housing with branch pipes. The pipes supply and discharge the flow of the working fluid. Turbines, depending on the working fluid used, are hydraulic, steam and gas. Depending on the average direction of flow through the turbine, they are divided into axial, in which the flow is parallel to the axis of the turbine, and radial, in which the flow is directed from the periphery to the center.
STEAM TURBINES
The main elements of a steam turbine are the casing, nozzles and rotor blades. Steam from an external source is supplied to the turbine through pipelines. In the nozzles, the potential energy of the steam is converted into the kinetic energy of the jet. The steam escaping from the nozzles is directed to curved (specially profiled) working blades located along the periphery of the rotor. Under the action of a jet of steam, a tangential (circumferential) force appears, causing the rotor to rotate.
Nozzles and blades.
Steam under pressure enters one or more stationary nozzles, in which it expands and from where it flows out at high speed. The flow exits the nozzles at an angle to the plane of rotation of the rotor blades. In some designs, the nozzles are formed by a series of fixed blades (nozzle apparatus). The impeller blades are curved in the direction of flow and arranged radially. In an active turbine (Fig. 1, A) the flow channel of the impeller has a constant cross-section, i.e. the speed in relative motion in the impeller does not change in absolute value. The steam pressure in front of and behind the impeller is the same. In a jet turbine (Fig. 1, b) the flow channels of the impeller have a variable cross-section. The flow channels of a jet turbine are designed so that the flow rate in them increases and the pressure drops accordingly.
R1; c – blading of the impeller. V1 – steam velocity at the nozzle exit; V2 – steam velocity behind the impeller in a fixed coordinate system; U1 – peripheral speed of the blade; R1 – steam velocity at the entrance to the impeller in relative motion; R2 – steam velocity at the exit from the impeller in relative motion. 1 – bandage; 2 – shoulder blade; 3 – rotor." title="Fig. 1. TURBINE WORKING BLADES. a – active impeller, R1 = R2; b – reactive impeller, R2 > R1; c – impeller blade. V1 – steam speed at the exit from the nozzle; V2 – steam velocity behind the impeller in a fixed coordinate system; U1 – peripheral speed of the blade; R1 – steam velocity at the entrance to the impeller in relative motion; R2 – steam velocity at the exit from the impeller in relative motion. 1 – bandage; 2 – blade; 3 – rotor.">Рис. 1. РАБОЧИЕ ЛОПАТКИ ТУРБИНЫ. а – активное рабочее колесо, R1 = R2; б – реактивное рабочее колесо, R2 > R1; в – облопачивание рабочего колеса. V1 – скорость пара на выходе из сопла; V2 – скорость пара за рабочим колесом в неподвижной системе координат; U1 – окружная скорость лопатки; R1 – скорость пара на входе в рабочее колесо в относительном движении; R2 – скорость пара на выходе из рабочего колеса в относительном движении. 1 – бандаж; 2 – лопатка; 3 – ротор.!}
Turbines are usually designed to be on the same shaft as the device that consumes their power. The rotation speed of the impeller is limited by the strength of the materials from which the disk and blades are made. For the most complete and efficient conversion of steam energy, turbines are made multi-stage.
Thermal cycles.
Rankine cycle.
Into a turbine operating according to the Rankine cycle (Fig. 2, A), steam comes from an external steam source; There is no additional heating of steam between turbine stages, there are only natural heat losses.
Reheat cycle.
In this cycle (Fig. 2, b) steam after the first stages is sent to the heat exchanger for additional heating (superheating). It then returns to the turbine, where its final expansion occurs in subsequent stages. Increasing the temperature of the working fluid makes it possible to increase the efficiency of the turbine.
Rice. 2. TURBINES WITH DIFFERENT THERMAL CYCLES. a – simple Rankine cycle; b – cycle with intermediate heating of steam; c – cycle with intermediate steam extraction and heat recovery.
A cycle with intermediate selection and recovery of waste steam heat.
The steam leaving the turbine still has significant thermal energy, which is usually dissipated in the condenser. Some of the energy can be recovered by condensing the exhaust steam. Some of the steam can be selected at the intermediate stages of the turbine (Fig. 2, V) and is used for preheating, for example, feed water or for any technological processes.
Turbine designs.
The working fluid expands in the turbine, therefore, in order to pass the increased volume flow, the last stages (low pressure) must have a larger diameter. The increase in diameter is limited by the permissible maximum stresses caused by centrifugal loads at elevated temperatures. In split-flow turbines (Figure 3), the steam passes through different turbines or different turbine stages.
Rice. 3. TURBINES WITH BRANCHING FLOW. a – twin parallel turbine; b – twin turbine of parallel action with oppositely directed flows; c – turbine with flow branching after several high-pressure stages; d – compound turbine.
Application.
To ensure high efficiency, the turbine must rotate at high speed, but the number of revolutions is limited by the strength of the turbine materials and the equipment that is located on the same shaft with it. Electric generators at thermal power plants are designed for 1800 or 3600 rpm and are usually installed on the same shaft as the turbine. Centrifugal blowers and pumps, fans and centrifuges can be installed on the same shaft with the turbine.
Low-speed equipment is coupled to a high-speed turbine through a reduction gearbox, such as in marine engines where the propeller must rotate at 60 to 400 rpm.
OTHER TURBINES
Hydraulic turbines.
In modern hydraulic turbines, the impeller rotates in a special casing with a scroll (radial turbine) or has a guide vane at the inlet that provides the desired direction of flow. The corresponding equipment (an electric generator at a hydroelectric power station) is usually installed on the shaft of a hydraulic turbine.
Gas turbines.
A gas turbine uses energy from combustion gases from an external source. Gas turbines are similar in design and operating principle to steam turbines and are widely used in technology. see also AIRCRAFT POWER PLANT; ELECTRIC ENERGY; SHIP POWER PLANTS AND PROPULSIONS; HYDROPOWER.
Literature
Uvarov V.V. Gas turbines and gas turbine plants. M., 1970
Verete A.G., Delving A.K. Marine steam power plants and gas turbines. M., 1982 equipment: basic (boiler installations and steam turbines) and auxiliary. For the powerful turbines(and we're talking...
Thermal trial gas turbine unit
Laboratory work >> PhysicsUPI" Department " Turbines and engines" Laboratory work No. 1 " Thermal trial gas turbine unit" Option... included in the complex equipment the test bench was turned on... the starting device was applied steam turbine built on the basis...
Choosing a diaphragm blade welding method steam turbines (2)
Coursework >> Industry, productionMelting using thermal energy (arc, ... parts steam turbines. shoulder blades steam turbines are divided... - manufacturability, - availability of necessary equipment, – availability of qualified personnel, – ... with appropriate tests. After that...
Thermal power unit diagram
Thesis >> Physics... test; ... equipment thermal power plants. – M.: Energoatomizdat, 1995. Ryzhkin V.Ya. Thermal... power plants. – M.: Energoatomizdat, 1987. Shklover G.G., Milman O.O. Research and calculation of condensing devices steam turbines ...
periodically during operation (at leastOnce every 3-4 years) to confirm compliance with standardstive characteristics.
In accordance with, based on the actual indicators obtained during thermal tests, the RD for fuel use is compiled and approved,
the validity period of which is established depending on the degree of its development and the reliability of the source materials, planned reconstructions and modernizations, equipment repairs, but cannot exceed 5 years.
Based on this, full thermal tests to confirm compliance of the actual characteristics of the equipment with the normative ones should be carried out by specialized commissioning organizations at least once every 3-4 years (taking into account the time required to process the test results, confirm or revise the RD).
By comparing the data obtained as a result of tests to assess the energy efficiency of a turbine installation (the maximum achievable electrical power with the corresponding specific heat consumption for electricity generation in condensing modes and with controlled extractions under the design thermal scheme and with nominal parameters and conditions, the maximum achievable supply of steam and heat for turbines with regulated selections, etc.) the expert organization on fuel use issues makes a decision to confirm or revise the RD.
List
references for chapter 4.4
GOST 24278-89. Stationary steam turbine installations for driving electric generators at thermal power plants. General technical requirements.
GOST 28969-91. Stationary steam turbines of low power. General technical requirements.
GOST 25364-97. Stationary steam turbine units. Vibration standards for shaft line supports and general requirements for measurements.
GOST 28757-90. Heaters for the regeneration system of steam turbines of thermal power plants. General technical conditions.
Collection of administrative documents on the operation of energy systems (Thermal Engineering Part). - M.: ZAO Energoservice, 1998.
Guidelines for checking and testing automatic control systems and protection of steam turbines: RD 34.30.310.- M.: SPO Soyuztekhenergo, 1984. (SO 153-34.30.310).
Amendment to RD 34.30.310. - M.: SPO ORGRES, 1997.
Standard operating instructions for oil systems of turbine units with a capacity of 100-800 MW operating on mineral oil: RD 34.30.508-93. - M.: SPO ORGRES, 1994. (SO 34.30.508-93).
Guidelines for the operation of condensing units of steam turbines of power plants: MU 34-70-122-85 (RD 34.30.501). - M.: SPO Soyuztekhenergo, 1986. (SO 34.30.501).
9. Standard operating instructions for systems
high pressure regeneration of power units with a capacity of 100-800 MW; RD 34.40.509-93, - M.: SPO ORGRES, 1994. (SO 34.40.509-93).
10. Standard instructions for the operation of the condensate path and low-pressure regeneration system of power units with a capacity of 100-800 MW at thermal power plants and thermal power plants: RD 34.40.510-93, - M.: SPO ORGRES, 1995. (SO 34.40.510-93).
P. Golodnova O.S. Operation of oil supply systems and seals of turbogenerators; hydrogen cooling. - M.: Energy, 1978.
Standard operating instructions for a gas-oil hydrogen cooling system for generators: RD 153-34.0-45.512-97.- M.: SPO ORGRES, 1998. (SO 34.45.512-97).
Guidelines for the conservation of thermal power equipment: RD 34.20,591-97. - M.: SPO ORGRES, 1997. (SO 34.20.591-97).
Thermal testing of steam turbines
and turbine equipment
In recent years, in the area of energy conservation, attention to fuel consumption standards for enterprises generating heat and electricity has increased, therefore, for generating enterprises, actual indicators of the efficiency of heat and power equipment are becoming important.
At the same time, it is known that actual efficiency indicators under operating conditions differ from the calculated (factory) ones, therefore, in order to objectively normalize fuel consumption for the production of heat and electricity, it is advisable to test equipment.
Based on equipment testing materials, standard energy characteristics and a model (procedure, algorithm) for calculating specific fuel consumption rates are developed in accordance with RD 34.09.155-93 “Guidelines for the compilation and content of energy characteristics of thermal power plant equipment” and RD 153-34.0-09.154 -99 “Regulations on the regulation of fuel consumption at power plants.”
Testing of thermal power equipment is of particular importance for facilities operating equipment put into operation before the 70s and where boilers, turbines, and auxiliary equipment were modernized and reconstructed. Without testing, rationing fuel consumption according to calculated data will lead to significant errors not in favor of generating enterprises. Therefore, the costs of thermal testing are insignificant compared to the benefits from them.
The objectives of thermal testing of steam turbines and turbine equipment:
|
|
The objectives of express testing of steam turbines are:
|
Modern technologies and the level of engineering knowledge make it possible to economically modernize units, improve their performance and increase their service life.
The main goals of modernization are:
- reduction of power consumption of the compressor unit;
- increasing compressor performance;
- increasing the power and efficiency of the process turbine;
- reduction of natural gas consumption;
- increasing the operational stability of equipment;
- reducing the number of parts by increasing the pressure of compressors and operating turbines on fewer stages while maintaining and even increasing the efficiency of the power plant.
Improvement of the given energy and economic indicators of the turbine unit is carried out through the use of modernized design methods (solving direct and inverse problems). They are connected:
- with the inclusion of more correct models of turbulent viscosity in the calculation scheme,
- taking into account the profile and end obstruction by the boundary layer,
- elimination of separation phenomena with an increase in the diffusivity of the interscapular channels and a change in the degree of reactivity (pronounced unsteadiness of the flow before the surge occurs),
- the ability to identify an object using mathematical models with genetic optimization of parameters.
The ultimate goal of modernization is always to increase production of the final product and minimize costs.
An integrated approach to the modernization of turbine equipment
When carrying out modernization, Astronit usually uses an integrated approach, in which the following components of the technological turbine unit are reconstructed (modernized):
- compressor;
- turbine;
- supports;
- centrifugal compressor-supercharger;
- intercoolers;
- animator;
- Lubrication system;
- air purification system;
- automatic control and protection system.
Modernization of compressor equipment
The main areas of modernization practiced by Astronit specialists:
- replacement of flow parts with new ones (so-called replaceable flow parts, including impellers and blade diffusers), with improved characteristics, but within the dimensions of existing housings;
- reducing the number of stages by improving the flow part based on three-dimensional analysis in modern software products;
- application of easy-to-work coatings and reduction of radial clearances;
- replacing seals with more efficient ones;
- replacement of compressor oil bearings with “dry” bearings using magnetic suspension. This allows you to eliminate the use of oil and improve the operating conditions of the compressor.
Implementation of modern control and protection systems
To increase operational reliability and efficiency, modern instrumentation, digital automatic control and protection systems (both individual parts and the entire technological complex as a whole), diagnostic systems and communication systems are being introduced.
- STEAM TURBINES
- Nozzles and blades.
- Thermal cycles.
- Rankine cycle.
- Reheat cycle.
- A cycle with intermediate selection and recovery of waste steam heat.
- Turbine designs.
- Application.
- OTHER TURBINES
- Hydraulic turbines.
- Gas turbines.
Scroll up Scroll down
Also on topic
- AIRCRAFT POWER PLANT
- ELECTRIC ENERGY
- SHIP POWER PLANTS AND PROPULSIONS
- HYDROPOWER
TURBINE
TURBINE, a prime mover with rotational movement of the working element to convert the kinetic energy of the flow of a liquid or gaseous working fluid into mechanical energy on the shaft. The turbine consists of a rotor with blades (bladed impeller) and a housing with branch pipes. The pipes supply and discharge the flow of the working fluid. Turbines, depending on the working fluid used, are hydraulic, steam and gas. Depending on the average direction of flow through the turbine, they are divided into axial, in which the flow is parallel to the axis of the turbine, and radial, in which the flow is directed from the periphery to the center.
STEAM TURBINES
The main elements of a steam turbine are the casing, nozzles and rotor blades. Steam from an external source is supplied to the turbine through pipelines. In the nozzles, the potential energy of the steam is converted into the kinetic energy of the jet. The steam escaping from the nozzles is directed to curved (specially profiled) working blades located along the periphery of the rotor. Under the action of a jet of steam, a tangential (circumferential) force appears, causing the rotor to rotate.
Nozzles and blades.
Steam under pressure enters one or more stationary nozzles, in which it expands and from where it flows out at high speed. The flow exits the nozzles at an angle to the plane of rotation of the rotor blades. In some designs, the nozzles are formed by a series of fixed blades (nozzle apparatus). The impeller blades are curved in the direction of flow and arranged radially. In an active turbine (Fig. 1, A) the flow channel of the impeller has a constant cross-section, i.e. the speed in relative motion in the impeller does not change in absolute value. The steam pressure in front of and behind the impeller is the same. In a jet turbine (Fig. 1, b) the flow channels of the impeller have a variable cross-section. The flow channels of a jet turbine are designed so that the flow rate in them increases and the pressure drops accordingly.
R1; c – blading of the impeller. V1 – steam velocity at the nozzle exit; V2 – steam velocity behind the impeller in a fixed coordinate system; U1 – peripheral speed of the blade; R1 – steam velocity at the entrance to the impeller in relative motion; R2 – steam velocity at the exit from the impeller in relative motion. 1 – bandage; 2 – shoulder blade; 3 – rotor." title="Fig. 1. TURBINE WORKING BLADES. a – active impeller, R1 = R2; b – reactive impeller, R2 > R1; c – impeller blade. V1 – steam speed at the exit from the nozzle; V2 – steam velocity behind the impeller in a fixed coordinate system; U1 – peripheral speed of the blade; R1 – steam velocity at the entrance to the impeller in relative motion; R2 – steam velocity at the exit from the impeller in relative motion. 1 – bandage; 2 – blade; 3 – rotor.">Рис. 1. РАБОЧИЕ ЛОПАТКИ ТУРБИНЫ. а – активное рабочее колесо, R1 = R2; б – реактивное рабочее колесо, R2 > R1; в – облопачивание рабочего колеса. V1 – скорость пара на выходе из сопла; V2 – скорость пара за рабочим колесом в неподвижной системе координат; U1 – окружная скорость лопатки; R1 – скорость пара на входе в рабочее колесо в относительном движении; R2 – скорость пара на выходе из рабочего колеса в относительном движении. 1 – бандаж; 2 – лопатка; 3 – ротор.!}
Turbines are usually designed to be on the same shaft as the device that consumes their power. The rotation speed of the impeller is limited by the strength of the materials from which the disk and blades are made. For the most complete and efficient conversion of steam energy, turbines are made multi-stage.
Thermal cycles.
Rankine cycle.
Into a turbine operating according to the Rankine cycle (Fig. 2, A), steam comes from an external steam source; There is no additional heating of steam between turbine stages, there are only natural heat losses.
The main objectives of the tests are to assess the actual state of the turbine unit and its components; comparison with the manufacturer’s guarantees and obtaining data necessary for planning and standardizing its work; optimization of modes and periodic monitoring of the efficiency of its operation with the issuance of recommendations for increasing efficiency.
Depending on the goals of the work, the total scope of tests and measurements, as well as the types of instruments used, are determined. For example, tests in category I of complexity (such tests are also called “balance” or complete) of prototype turbine samples, turbines after reconstruction (modernization), as well as turbines that do not have a standard energy characteristic, require a large volume of measurements of a high accuracy class with mandatory balancing the main flow rates of steam and water.
Based on the results of several tests of turbines of the same type in complexity category I, standard energy characteristics are developed, the data of which are taken as the basis for determining the standard indicators of equipment.
For all other types of tests (according to complexity category II), as a rule, particular problems are solved, such as determining the effectiveness of repairing a turbine installation or modernizing its individual components, periodically monitoring the condition during the overhaul period, and experimentally finding some correction dependencies for the deviation of parameters from nominal, etc. Such tests require a significantly smaller volume of measurements and allow the widespread use of standard instruments with their mandatory verification before and after testing; The thermal design of the turbine installation should be as close as possible to the design design. Processing of test results for category II of complexity is carried out using the “constant fresh steam flow” method (see Section E.6.2) using correction curves based on data from standard energy characteristics or manufacturers.
Along with the above, tests can also pursue narrower goals, for example, determining the comparative efficiency of modes with “cut-off LPC” for T-250/300-240 turbines, finding power corrections for changes in exhaust steam pressure in the condenser when operating according to a thermal schedule, determining losses in the generator, maximum throughput of the steam inlet and flow path, etc.
In these Guidelines, the main attention is paid to issues related only to testing turbines in category I of complexity, as representing the greatest difficulty at all stages. The test methodology for complexity category II will not present any great difficulties after mastering the test methodology for complexity category I, since tests for complexity category II, as a rule, require a significantly smaller volume of measurements and cover components and elements of a turbine installation, controlled according to complexity category I, consist of a small number of experiments that do not require compliance with strict and numerous requirements for the thermal design and conditions for their conduct.
B. TEST PROGRAM
B.1. General provisions
After a clear clarification of the goals and objectives of the tests, in order to draw up their technical program, it is necessary to carefully familiarize yourself with the turbine installation and have complete information about:
Condition and its compliance with design data;
Its capabilities from the point of view of ensuring the flow of fresh steam and steam of controlled extractions, as well as electrical load in the required range of their change;
Its ability to maintain steam and water parameters during experiments close to nominal and constant opening of steam distribution organs;
The possibility of its operation with a design thermal scheme, the presence of restrictions and intermediate inlets and outlets of extraneous steam and water and the possibility of excluding them or, in extreme cases, taking them into account;
The capabilities of the measuring circuit to provide reliable measurements of parameters and flow rates over the entire range of their change.
Sources for obtaining this information may be technical conditions (TS) for the supply of equipment, instructions for its operation, audit reports, lists of defects, analysis of readings from standard recording devices, personnel interviews, etc.
The test program must be drawn up in such a way that, based on the results of the experiments, the dependences of both the general indicators of the efficiency of the turbine unit (consumption of fresh steam and heat from the electrical load and the consumption of steam from controlled extractions) and private indicators characterizing the efficiency can be calculated and plotted in the required range individual sections (cylinders) of the turbine and auxiliary equipment (for example, internal efficiency, stage pressures, heater temperature drops, etc.).
General efficiency indicators obtained from the test make it possible to evaluate the level of the turbine installation in comparison with guarantees and data for turbines of the same type, and are also the source material for planning and standardizing its operation. Particular performance indicators, by analyzing them and comparing them with design and regulatory data, help to identify components and elements that operate with reduced efficiency and timely outline measures to eliminate defects.
AT 2. Test program structure
The technical test program consists of the following sections:
Test objectives;
List of modes. In this section, for each series of modes, the consumption of fresh steam and steam in the regulated extractions, the pressure in the regulated extractions and the electrical load are indicated, as well as a brief description of the thermal circuit, the number of experiments and their duration;
- general test conditions. This section specifies the basic requirements for the thermal circuit, gives the limits for deviation of steam parameters, a method for ensuring constant operation, etc.
The testing program is coordinated with the heads of the following workshops: boiler and turbine, adjustment and testing, electrical, technical and technical departments and approved by the chief engineer of the power plant. In some cases, for example, when testing prototype turbines, the program is also agreed upon with the manufacturer and approved by the chief engineer of the power system.
AT 3. Development of test programs for turbines of various types
B.3.1. Condensing and back pressure turbines
The main characteristics of turbines of this type are the dependences of fresh steam consumption and heat (total and specific) on the electrical load, therefore the main part of the test program is devoted to experiments to obtain precisely these dependences. Experiments are carried out at the design thermal circuit and nominal steam parameters in the range of electrical loads from 30-40% of the nominal to maximum.
To be able to construct the characteristics of turbines with back pressure over the entire range of changes in the latter, either three series of experiments are carried out (at maximum, nominal and minimum back pressure), or only one series (at nominal back pressure) and experiments to determine the correction to power for changes in back pressure.
The selection of intermediate loads is carried out in such a way as to cover all characteristic points of dependencies, corresponding, in particular:
The opening moments of control valves;
Switching the deaerator power source;
Transition from an electric feed pump to a turbopump;
Connecting the second boiler body (for double-block turbines).
The number of experiments at each load is: 2-3 at maximum, nominal and at characteristic points and 1-2 at intermediate ones.
The duration of each experiment, excluding mode adjustment, is at least 1 hour.
Before the main part of the test, it is planned to conduct so-called calibration experiments, the purpose of which is to compare fresh steam flow rates obtained by independent methods, which will make it possible to judge the “density” of the installation, i.e., the absence of noticeable unaccounted for steam and water supplies or their removal from the cycle. Based on the analysis of the convergence of the compared costs, it is also concluded that the determination of any of them is more reliable; in this case, when processing the results, a correction factor is introduced to the flow rate obtained by another method. Carrying out these experiments may be especially necessary in the case where one of the restrictive measuring devices is installed or performed in a deviation from the rules.
It should also be taken into account that the results of calibration experiments can be used to more accurately determine by calculation the internal efficiency of the LPC, since in this case the number of quantities participating in the energy balance equation of the installation is reduced to a minimum.
To carry out calibration experiments, a thermal circuit is assembled in which the flow of fresh steam can be measured almost entirely in the form of condensate (or exhaust steam for turbines with back pressure), which is achieved by turning off the regenerative extractions at the HPH (or transferring their condensate to a cascade discharge into the condenser ), deaerator, if possible at the HDPE (if there is a device for measuring condensate flow behind the condensate pumps) and all selections for general plant needs. In this case, all steam and water supplies and their outlets from the turbine unit cycle must be reliably disconnected and equal levels in the condenser must be ensured at the beginning and end of each experiment.
The number of calibration experiments in the range of changes in fresh steam flow from minimum to maximum is at least 7-8, and the duration of each is at least 30 minutes, provided that the pressure drops on the flow meters and the parameters of the environment in front of them are recorded every minute.
In the absence of a reliable dependence of the change in power on the exhaust steam pressure, the need arises to conduct so-called vacuum experiments, during which the thermal circuit practically corresponds to that collected for calibration experiments. In total, two series of experiments are carried out with a change in the exhaust steam pressure from minimum to maximum: one - with steam flow in the low-pressure pump close to the maximum, and the second - about 40% of the maximum. Each series consists of 10-12 experiments with an average duration of 15-20 minutes. When planning and conducting vacuum experiments, special attention should be paid to the need to ensure the minimum possible fluctuations in the initial and final steam parameters in order to eliminate or minimize adjustments to the turbine power to take them into account and, therefore, obtain the most representative and reliable dependence. The program should also specify a method for artificially changing the exhaust steam pressure from experiment to experiment (for example, introducing air into the condenser, reducing the working steam pressure in front of the ejectors, changing the cooling water flow rate, etc.).
Along with the above, some special experiments may be planned (for example, to determine the maximum power and throughput of a turbine, with sliding pressure of fresh steam, to test the effectiveness of the implementation of various measures to determine the efficiency of the low-pressure pump, etc.).
B.3.2. Turbines with controlled steam extraction for district heating
Turbines of this type (T) are made either with one stage of T-extraction, taken from the chamber in front of the regulator (these are, as a rule, turbines of old output and low power, for example, T-6-35, T-12-35, T- 25-99, etc., in which single-stage heating of network water is carried out), or with two stages of T-selection, one of which is fed from the chamber in front of the regulatory body (NTO), and the second - from a chamber located, as a rule, two stages above the first (WTO) are, for example, turbines T-50-130, T, T-250/300-240 and others, currently produced and operating according to a more economical scheme with multi-stage heating of network water.
In turbines with multi-stage, and after appropriate reconstruction, in turbines with single-stage heating of network water, in order to recover the heat of exhaust steam in the heat schedule mode, a specially built-in bundle (BP) is specially allocated in the condenser, in which preheating of network water occurs before supplying it to the PSV. Thus, depending on the number of heating stages of network water, modes differ with one-stage heating (LTO included), two-stage (LTO and WTO included) and three-stage (VP, LTO and WTO included).
The main relationship characteristic of turbines of this type is the regime diagram, reflecting the relationship between the flow rates of fresh steam and steam in the T-extraction and electrical power. Being necessary for planning purposes, the regime diagram is at the same time the source material for calculating and normalizing the economic indicators of a turbine installation.
Diagrams of modes for turbine operation with one-, two- and three-stage schemes for heating network water are assumed to be double-field. Their upper field shows the dependence of the turbine power on the fresh steam flow rate when operating according to the thermal schedule, i.e., with a minimum steam flow into the low-pressure pump and various pressures in the RTO.
The lower field of the mode diagram contains the dependences of the maximum heating load on the turbine power, corresponding to the above-mentioned lines of the upper field. Additionally, in the lower field there are lines characterizing the dependence of the change in electrical power on the heating load when the turbine operates according to the electrical schedule, i.e., when steam flows into the LPC are greater than the minimum (only for one- and two-stage heating of network water).
Summer operating modes of turbines in the absence of heating load are characterized by dependencies of the same type as for condensing turbines.
When testing turbines of this type, as for condensing turbines, there may also be a need to experimentally determine some correction curves for turbine power for the deviation of certain parameters from the nominal ones (for example, exhaust steam pressure or RTO steam).
Thus, the testing program for turbines of this type consists of three sections:
Experiments in condensation mode;
Experiments to construct a regime diagram;
Experiments to obtain correction curves.
Each section is discussed separately below.
B.3.2.1. Condensation mode with the pressure regulator turned off in the RTO
This section consists of three parts, similar to those specified in the test program for the condensing turbine (calibration experiments, experiments with the design thermal circuit and experiments to determine the power correction for changes in exhaust steam pressure in the condenser) and does not require any special explanation.
However, due to the fact that, as a rule, the maximum flow rate of fresh steam in calibration experiments for turbines of this type is determined by the maximum flow rate in the low pressure pump, ensuring a pressure drop in the restriction devices on the fresh steam lines in the range above this flow rate to the maximum is carried out either by throttling the fresh steam, either by turning on HPHs with the direction of their heating steam condensate into the condenser, or by turning on controlled extraction and gradually increasing it.
B.3.2.2. Experiments for constructing a regime diagram
From the structure of the diagram described above it follows that to construct it it is necessary to carry out the following series of experiments:
Thermal graph with different pressures in the RTO (to obtain the main dependencies of the upper and lower fields of the diagram. For each of the modes with one-, two- and three-stage heating of network water, 3-4 series (6-7 experiments in each) with different constants are planned pressures in the RTO, equal or close, respectively, to the maximum, minimum and average.The range of changes in the fresh steam flow rate is determined mainly by the limitations of the boiler, the requirements of the instructions and the possibility of reliable measurement of flow rates;
Electrical graph with constant pressure in the RTO (to obtain the dependence of the change in power on the change in heating load). For each of the modes with one- and two-stage heating of network water at a constant flow of fresh steam, 3-4 series (5-6 experiments in each) are planned with constant pressure in the RTO and variable heating load from maximum to zero; It is recommended to turn off the PVD to ensure the greatest accuracy.
B.3.2.3. Experiments to construct power correction curves for the deviation of individual parameters from their nominal values
It is necessary to carry out the following series of experiments:
Thermal graph with constant fresh steam flow and variable pressure in the RTO (to determine the correction to turbine power for changes in pressure in the RTO). For modes with one- and two-stage (or three-stage) heating of network water, two series of 7-8 experiments are carried out with a constant flow of fresh steam in each and a change in pressure in the RTO from minimum to maximum. Changing the pressure in the RTO is achieved by changing the flow of network water through the PSV with the constant opening of the fresh steam valves and the minimum opening of the rotary diaphragm of the low pressure pump.
High pressure heaters are disabled to improve the accuracy of the results;
Experiments to calculate the correction to power for changes in exhaust steam pressure in the condenser. Two series of experiments are carried out at steam flows into the condenser of the order of 100 and 40% of the maximum. Each series consists of 9-11 experiments lasting about 15 minutes over the entire range of changes in exhaust steam pressure, carried out by admitting air into the condenser, changing the flow rate of cooling water, steam pressure through the main ejector nozzles, or the flow rate of the steam-air mixture sucked from the condenser.
B.3.3. Turbines with controlled steam extraction for production
Turbines of this type have a very limited distribution and are produced either with condensation (P) or with back pressure (PR). In both cases, the diagram of their operating modes is single-field and contains the dependence of electric power on the flow of fresh steam and P-bleed steam.
By analogy with Sect. B.3.2 the test program also contains three sections.
B.3.3.1. Mode without P-selection
The following experiments must be carried out:
- "calibration". Conducted under the conditions specified in section. B.3.1 and B.3.2.1;
Under normal thermal design. They are carried out with the pressure regulator in the P-extraction switched off at a constant exhaust steam pressure (for turbines of the PR type).
B.3.3.2. Experiments for constructing a regime diagram
Due to the fact that the steam in the P-selection chamber is always superheated, it is enough to carry out one series of experiments with controlled steam extraction, based on the results of which the characteristics of the high-pressure pressure and low-pressure pressure, and then the regime diagram are then calculated and constructed.
B.3.3.3. Experiments for constructing power correction curves
If necessary, experiments are carried out to determine power corrections for changes in the pressure of the exhaust steam and steam in the P-bleed chamber.
B.3.4. Turbines with two adjustable steam extractions for production and district heating (PT type)
The diagram of modes for turbines of this type is not fundamentally different from the traditional diagrams of double-extraction turbines PT-25-90 and PT-60 with one heating extraction outlet and is also double-field, with the upper field describing the modes with production extraction, and the lower - with heating extraction with one - and two-stage heating of network water. Thus, to build a diagram you need to have the following dependencies:
HPC and LPC power as a function of inlet steam flow at selected nominal pressures in the P-selection and RTO and zero heating load (for the upper field);
Changes in the total power of the switchable compartment (SC) and CND for two-stage heating and CND for single-stage heating from changes in the heating load.
In order to obtain the mentioned dependencies, it is necessary to carry out the following series of experiments.
B.3.4.1. Condensation mode
Experiments are carried out in this mode:
- “calibration” (PVD and pressure regulators in the extractions are disabled). Such experiments are carried out with a thermal design of the installation assembled in such a way that the flow of fresh steam passing through the flow metering device can be measured almost entirely in the form of condensate using a restriction device installed on the main condensate line of the turbine. The number of experiments is 8-10, each lasting 30-40 minutes (see sections B.3.1 and B.3.2.1);
To calculate the power correction for changes in exhaust steam pressure in the condenser. Pressure regulators in the selections are disabled, regeneration is disabled, with the exception of HDPE No. 1 and 2 (see section B.3.1);
To determine the correction to power for changes in steam pressure in the RTO (HVDs are turned off, the P-extraction pressure regulator is turned on). 4 series are carried out with a constant flow of fresh steam (4-5 experiments in each), in two of which the pressure in the WTO changes in steps from minimum to maximum, and in the other two - in the LTO;
With the design thermal scheme. Conducted under conditions similar to those specified in section. B.3.1.
B.3.4.2. Modes with production selection
A series of 4-5 experiments is carried out in the flow range from the maximum in condensation mode () to the maximum permissible when the HPC is fully loaded with steam ().
The P-selection value is selected according to the conditions of the thermal power plant, based on the desirability of ensuring controlled pressure behind the HPC in the entire series of experiments.
B.3.4.3. Modes with district heating extraction according to an electrical schedule (to obtain the dependence of power changes on changes in heating load)
These modes are similar to those carried out when testing turbines without P-bleed.
For modes with one- and two-stage heating of network water with the HPH turned off and the fresh steam flow constant, 3-4 series of 5-6 experiments are carried out in each with a constant pressure in the RTO, close to the minimum, intermediate and maximum, respectively.
The heating load changes from maximum to zero in each series of experiments by changing the flow of network water through the PSV pipe bundles.
D. PREPARATION FOR TESTS
D.1. General provisions
Preparation for testing is usually carried out in two stages: the first covers work that can and should be carried out relatively long before testing; the second covers the work that is carried out immediately before testing.
The first stage of preparation includes the following work:
Detailed familiarization with the turbine installation and instrumentation;
Drawing up a technical test program;
Drawing up an experimental control scheme (measurement scheme) and a list of preparatory work;
Drawing up a list (specification) of necessary instrumentation, equipment and materials.
At the second stage of preparation the following is performed:
Technical guidance and supervision of preparatory work on equipment;
Installation and adjustment of the measurement circuit;
Monitoring the technical condition of equipment and thermal circuits before testing;
Breakdown of measurement points according to observation logs;
Drawing up work programs for individual series of experiments.
D.2. Familiarization with the turbine installation
When familiarizing yourself with the turbine installation, you must:
Study the technical specifications for delivery and design data of the manufacturer, technical inspection reports, defect logs, operational data, standards and instructions;
Study the thermal diagram of the turbine installation from the point of view of identifying and, if necessary, eliminating or taking into account various intermediate inlets and outlets of steam and water for the duration of the test;
Determine what measurements need to be made to solve the problems assigned to the test. Check locally the presence, condition and location of existing measuring devices suitable for use during testing as primary or backup ones;
Identify, through on-site inspection and questioning of operating personnel, as well as studying technical documentation, all noticed malfunctions in the operation of the equipment, relating, in particular, to the density of shut-off valves, heat exchangers (regenerative heaters, EPS, condenser, etc.), operation of the control system , the ability to maintain stable load conditions and steam parameters (fresh and controlled extractions) required during testing, operation of level regulators in regenerative heaters, etc.
As a result of preliminary familiarization with the turbine installation, it is necessary to clearly understand all the differences in its thermal circuit from the design one and the parameters of steam and water from the nominal ones that may occur during testing, as well as how to subsequently take these deviations into account when processing the results.
D.3. Measurement diagram and list of preparatory work
After a detailed acquaintance with the turbine installation and drawing up a technical testing program, one should begin to develop a measurement scheme with a list of measured quantities, the main requirement for which is to ensure the possibility of obtaining representative data characterizing the efficiency of the turbine installation as a whole and its individual elements in the entire range of modes outlined by the technical program. To this end, when developing a measurement scheme, it is recommended to base the following principles:
Use of sensors and instruments of maximum accuracy to measure the basic parameters of steam and water, generator power and flow rates;
Ensuring that the measurement limits of the selected instruments correspond to the expected range of changes in the recorded values;
Maximum duplication of measurements of basic quantities with the possibility of their comparison and mutual control. Connecting duplicate sensors to different secondary devices;
Use standard measuring instruments and sensors within reasonable limits.
A measurement diagram for the turbine installation during testing, lists of preparatory work (with sketches and drawings) and measurement points, as well as a list of necessary instrumentation (specification) are drawn up as an appendix to the technical program.
D.3.1. Drawing up a measurement scheme and a list of preparatory work for a turbine in operation
The thermal circuit of the turbine installation during testing must ensure reliable isolation of this installation from the general circuit of the power plant, and the measurement circuit must ensure the correct and, if possible, direct determination of all quantities necessary to solve the problems assigned to the test. These measurements should give a clear picture of the flow balance, the process of steam expansion in the turbine, the operation of the steam distribution system and auxiliary equipment. All critical measurements (for example, fresh steam flow, turbine power, parameters of fresh and exhaust steam, reheat steam, flow and temperature of feed water, main condensate, pressure and temperature of steam in the controlled extraction and a number of others) must be duplicated, using the connection of independent primary converters to redundant secondary devices.
The thermal diagram is accompanied by a list of measurement points indicating their names and numbers according to the diagram.
Based on the developed measurement scheme and detailed familiarization with the installation, a list of preparatory work for testing is compiled, which indicates where and what measures need to be performed to organize a particular measurement and bring the circuit or equipment to normal condition (repairing fittings, installing plugs, cleaning surfaces heating heaters, condensers, eliminating hydraulic leaks in heat exchangers, etc.). In addition, the list of works provides, if necessary, for the organization of additional lighting at observation sites, the installation of signaling devices and the manufacture of various stands and devices for the installation of primary transducers, connecting (pulse) lines and secondary devices.
The list of preparatory work must necessarily include sketches for the manufacture of the necessary primary measuring devices (lugs, fittings, thermometric sleeves, measuring constriction devices, etc.), sketches of the insertion locations for the specified parts, as well as various stands and devices for installing devices. It is also advisable to attach a summary statement of materials (pipes, fittings, cables, etc.) to the list.
The primary measuring devices listed above, as well as the necessary materials, are selected according to current standards in accordance with the parameters of the measured medium and technical requirements.
D.3.2. Drawing up a measurement scheme and a list of preparatory work for a newly installed turbine
For a newly installed turbine, in particular the prototype, a slightly different approach is required to drawing up a measurement scheme (or experimental control - EC) and issuing assignments for preparatory work. In this case, preparation of the turbine for testing should begin already during its design, which is caused by the need to provide in advance additional taps into the pipelines for installing measuring devices, since with modern thick-walled pipelines and a large volume of measurements caused by the complexity of the thermal circuit, all this work must be performed by power plants after the equipment is put into operation it turns out to be almost impossible. In addition, the EC project includes a significant amount of instrumentation and necessary materials that the power plant is not able to purchase with their non-centralized supply.
Just as when preparing to test turbines already in operation, you must first study the technical specifications for the supply and design data of the manufacturer, the thermal diagram of the turbine installation and its connection with the general circuit of the power plant, familiarize yourself with standard measurements of steam and water parameters, and decide , which can be used during testing as primary or backup measurements, etc.
After clarifying the listed issues, you can begin to draw up the technical specifications of the design organization for inclusion in the working design of the station instrumentation of the EC project for thermal testing of the turbine unit.
- explanatory note, which sets out the basic requirements for the design and installation of an EC circuit, the selection and location of instrumentation; explanations are given for information recording equipment, features of the use of types of wires and cables, requirements for the room in which the EC panel is supposed to be placed, etc.;
Diagram of the turbine installation EC with the name and numbers of measurement positions;
Specification for instrumentation;
Schemes and drawings for the manufacture of non-standard equipment (panel devices, segment diaphragms, intake devices for measuring vacuum in a condenser, etc.);
Diagrams of pipe connections of pressure and differential pressure transducers, which provide various options for connecting them, indicating the numbers of measurement positions;
A list of measured parameters, broken down by recording devices, indicating item numbers.
Places for insertion of measuring devices for EC on working drawings of pipelines are usually indicated by the design organization and the manufacturer (each in its own design area) in accordance with the technical specifications. If there are no tie-ins anywhere in the drawings, this is done by the enterprise that issued the technical specifications for the EC with a mandatory visa from the organization that issued this drawing.
It is advisable to install the EC circuit during the installation of the standard instrumentation volume of the turbine installation, which allows testing to begin soon after the turbine installation is put into operation.
As an example, Appendices 4-6 show diagrams of the main measurements when testing turbines of different types.
D.4. Selection of instrumentation
The selection of instrumentation is carried out in accordance with the list compiled on the basis of the test measurement scheme.
For this purpose, only such instruments should be used whose readings can be verified by comparison with standard ones. Devices with a unified output signal for automatic recording of parameters are selected according to the class of accuracy and reliability in operation (stability of readings).
The list of instrumentation required for testing must indicate the name of the measured quantity, its maximum value, type, accuracy class and scale of the device.
Due to the large volume of measurements when testing modern powerful steam turbines, the recording of measured parameters during experiments is often carried out not by observers using direct-acting instruments, but by automatic recording devices with recording of readings on a chart tape, multi-channel recording devices with recording on punched tape or magnetic tape, or operational information and computing complexes (ICC). In this case, measuring devices with a unified output current signal are used as primary measuring devices. However, under the conditions of power plants (vibration, dust, influence of electromagnetic fields, etc.), many of these devices do not provide the necessary stability of readings and require constant adjustment. More preferable in this regard are the recently produced strain gauge transducers "Sapphire-22", which have a high accuracy class (up to 0.1-0.25) and sufficient stability of operation. It should, however, be borne in mind that when using the above converters, it is advisable to duplicate the most critical measurements (for example, pressure in an adjustable T-selection, vacuum in a condenser, etc.) (at least during the period of gaining experience with them) using mercury devices.
To measure the pressure difference in the constriction device, the following are used: up to a pressure of 5 MPa (50 kgf/cm2) two-pipe differential pressure gauges DT-50 with glass tubes, and at pressures above 5 MPa - single-pipe differential pressure gauges DTE-400 with steel tubes, the mercury level in which is measured visually on a scale using an inductive pointer.
In an automated system for measuring pressure drop, transducers with a unified output signal of the DME type, accuracy class 1.0, of the Kazan Instrument-Making Plant, the DSE type, accuracy class 0.6, of the Ryazan Teplopribor plant, and the above-mentioned strain gauge transducers "Sapfir-22" ("Sapfir- 22DD") of the Moscow Instrument-Making Plant "Manometer" and the Kazan Instrument-Making Plant.
As direct-acting devices that measure pressure, for pressures above 0.2 MPa (2 kgf/cm2) spring pressure gauges of accuracy class 0.6 type MTI of the Moscow Instrument-Making Plant "Manometer" are used, and for pressures below 0.2 MPa (2 kgf /cm2) - mercury U-shaped manometers, single-pipe cup vacuum gauges, barovacuum tubes, as well as spring vacuum gauges and pressure vacuum gauges with an accuracy class of up to 0.6.
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