1.2. Turbogenerator
A turbo-generator comprising a shaft, on which is positioned an axial ventilator, a cover that divides an inflow chamber for a cooling gas transported by the axial ventilator from an outflow chamber for this cooling gas, and a cylindrical channel segment that is positioned coaxially to the axial compressor and surrounds the axial compressor radially, whereby the inflow chamber comprises an asymmetrical cooling gas supply, and whereby in the inflow chamber means for homogenizing the cooling gas supply to the axial ventilator are provided. In order to improve the cooling, and therefore the efficiency of the machine, the inflow chamber forms a rotation-symmetrical annular chamber in the region of an inflow opening of the channel segment. A cylindrical annular collar is positioned coaxially to the axial ventilator within this annular chamber. The annular collar projects axially into the annular chamber and forms a completely surrounding, radial throttling gap at the inflow opening.
Introduction. Advantages of powerful turbogenerators with water and oil cooling
At water and oil cooling of the turbogenerators, it will be done:
direct cooling of the active and design parts of stator by insulating oil at filling of stator by this oil, at that, the oil volume in stator is limited by stator case, end shields and insulation cylinder mounted at the air gap and fixed at the shields;
paper and oil insulation for stator winding;
water cooling of rotor winding.
The experience of many year service of TBM-60 turbogenerators of capacity 60 MW (since 1963), TBM-300 of capacity 300 MW (since 1968) and TBM-500 of capacity 500 MW (since 1978) with such cooling system and stator winding insulation, and also, the results of special researches and industrial tests of these turbogenerators have shown that the water and oil cooling system provides a number of the advantages in comparison with the other cooling and insulation systems.
The main advantages:
1. High reliability that is reasoned by:
absence of big number of the supplies of cooling liquid to stator winding and elements as a supply and drainage of cooling oil for winding bars and stator core are done at the oil filled cavities, at that, all hydraulic circuits inside the stator do not require the guaranteed tightness as at water cooling;
high level of reserve of electric strength and resistance of paper and oil insulation to the mechanic influences at vibrations and deformation s of bars that allowed to define the periodicity of the capital repairs of stator in 10 years instead of 4-5;
protection ability of inner stator cavity from outer influences (moisture, dust and others).
2. The higher overloading abilities and more extended capabilities of operation at abnormal modes (operation at under-excitation is limited by static stability, at asynchronous mode, it is admitted the durable operation at active power 40 % of rated one, at asymmetrical load, it is admitted the durable operation with inverse current up to 10 % of rated value of stator current).
3. The high efficiency at whole operation range of the loads due to relatively low level of the mechanical losses at generator and additional losses at winding and end parts of stator.
4. The ability of preventing determination of core status and insulation of stator winding by gas chromatography method.
5. The relative simplicity of mounting and maintenance.
6. The higher repair ability of stator winding as the over-monolithising for the straight portions is absent, and a restoration of the case insulation of the bars by paper tapes can be done beyond the plant facilities.
7. The ability of the manufacturing of the turbogenerators for optimum voltage assuming the machine parameters.
Intention
The turbogenerator is intended for power generation at direct coupling with steam turbine.
Service contidions
The sea level is not more 1000 m. The range of admitted ambient temperature:
- upper value +40 C
-lower value +5 C
The environment is not explosion hazardous, no dust at the concentrations reducing the parameters of turbogenerators at non-admitted limits.
Function of efficiency against load
|
Load,r.u./MW |
0,5/160 |
0,75/240 |
1,0/320 |
1,1/352 |
|
Efficiency, % |
98,85 |
98,95 |
98,9 |
98,85 |
Admitted temperatures of heating
- stator winding, C 105
- stator core, C 105
- rotor winding (on resistance), C 75
- insulating oil at output of stator, C 90
- distillate at output of rotor, C 85
Admitted abnormal operation modes of turbogenerator
the turbogenerator admits the durable operation at asymmetrical load if the currents in phases do not excess the admitted value for these conditions of operation of the turbogenerator at symmetrical load, and inverse current, at that, must not excess 8 % of rated value of stator current.
the turbogenerator admits an operation at under-excitation mode at rated active power and power factor as 0,95 (leading).
The turbogenerator admits an operation at asynchronous mode during 15 minutes at consuming active power not more 60 % of rated one, during 30 minutes – at consuming power not more 50 % of rated one, and durably – at consuming power not more 40 % of rated one.
Desing version
The turbogenerator version is horizontal.
The stator core and winding are immersed into the insulating oil. The oil volume filling the stator is limited by case, end shields and insulation cylinder placed into the split of stator core. The insulation cylinder and end shields, at the places of joining to stator case, are sealed with the rings of rubber cord. To extract the rotor for its overview and prophylactic repair, it is not necessary to drain oil from stator and remove the end shields. The stator case is one part and welded. The stator core is assembled of the insulated segments of electric steel in which, at stamping, the narrow rectangular holes creating the axial ducts at the core over which the insulating oil cooling the core floats, are cut off. The pressed core is laid axially and held by stuck packages and clamping non-magnetic elements. In the case, the core is fitted rigidly. The stator winding is three phase, two layer, with shortened pitch. The bars of the winding are done of the alternating hollow and solid wires. The oil floating over the ducts of the hollow wires cools the bars. The phases of the winding are connected into star.
The line and neutral terminals of the stator winding are led out the case of stator through the isolators and placed at the bottom of case. The plate, on which the terminals are fitted, is designed to connect the closed current supplies.
The rotor is done of the integral forging of special alloyed steel. The rotor winding consists of the concentric coils fabricated of the hollow copper with silver addition. The straight portions of the winding are fitted by slip rings of alloyed non-magnetic stainless steel. The cooling of the rotor winding is done by distillate which floats over the ducts of the wires. All coils over distillate are connected in parallel. The water supply and its drainage are fulfilled through the central hole of the shaft over the concentrically mounted pipes of stainless steel.
The slip rings are done of special steel and set onto the console shaft end. To cooling of the slip rings and brushes and remove the brush dust from an area of brush and contact device, between the slip rings on a shaft, the fan is mounted. The turbogenerator bearings are outboard thrust ones. The bearing from a side of the slip rings has the self-mounting insert with spherical setting in case. The bearing from a side of the turbine is built into the turbine case and supplied with the turbine.
The oil supply into the turbogenerator bearings are fulfilled from the lubrication system of the turbine bearings. To cool the turbogenerator, on the power plant, the cooling systems for stator and rotor with usage of equipment supplied with generator, must be mounted. The cooling of stator by insulating oil and of rotor by distillate is fulfilled over the close loop: electric pump – cooler – filter – cooled item – electric pump. For a circulation of oil, the watertight pumps without seals are used. At each system, the reserve pump, reserve cooler, reserve filter are installed. At cooling system of stator, for a compensation of temperature changes of insulating oil volume filling stator and system, at the input of the pumps, the extending sets are connected. One of them is operating, other is reserve one. The insulating oil purified from the mechanical additions and water with oil station of the power plant, before the stator filling and its cooling system, is degassed. The equipment for degassing and filling of stator and its system under vacuum, is supplied with the generator. One set of such equipment provides the maintenance of two or three identical turbogenerators installed at main room of the plant. The excitation system of the turbogenerator is thyristor one done with self-excitation circuit.
Supply scope of turbogenerator
the turbogenerator with sole plates and anchor pins;
stator cooling system;
rotor cooling system;
excitation system;
spare parts;
mounting tools and special instruments;
service documents.
Quality and guarantees
The development, conquest of the production, manufacturing and tests of the turbogenerator, NPO “ELSIB” OAO carries out in accordance with the requirements of ISO-9001-94 standard.
The turbogenerator meets the RF standards and IEC recommendations.
The enterprise guarantees the correspondence of the turbogenerator to the requirements of the standards at the condition of the keeping of service, transportation and storage rules stated by TU by customer.
The warranty term stated for the turbogenerator is 3 years since a date of commission, and for the turbogenerators intended for export – 1 year since a date of commission but not more 3 years since a moment of passage of the turbogenerator across the state boundary of RF.
Air-cooled turbogenerators
|
Convenience, simplicity and flexibility T Air-cooled generators is well suited to the cyclic and peak operating mode, allow achieving the high extent of automatization of the technological processes, reducing the operation costs significantly. Almost all generators supplied by “ELSIB” with capacity rated from 6 to 20 МW have the indirect cooling system of the rotor winding that provides the higher reliability and durability. The use of the joint insulating impregnation of the stator winding and core provides a higher resource on a capacity, heat loads and minimizes the vibration values. The coil and coil-bar stator windings allow to reduce a length of generator and increase its specific weight characteristics. A proved materials and excellently presented itself insulation system exclude an appearance of the damages at the coronas. The thermal-resistance insulation class is “F”. At the rated and maximum modes, it provides the use of “B” class insulation that allows ELSIB generators to operate at the extended modes and at the wider range of the environment. This characteristic is especially important for generators matched to the gas turbines, because capacity of those notably increases at the reduction of the ambient temperature. Air-cooled
generators operate with closed-loop cooling system. The air
circulation is provided with the axial fans on the shaft of rotor,
and the air-to-water heat exchangers located on each side of
generator remove heat from the air. The generators of power rating from 25 to 160 MW are produced at the one-piece welded case of cylindrical shape. The design of case provides the high rigidity and strength, that allows generators to operate reliably and stably at all operation modes include cycled load, peaking duty, overload modes. This is pledge of the generator durability and reliability providing for its high operational characteristics. The air circulating inside the generator over the close loop is cooled at the air-to-water heat exchangers built in the stator case horizontally. The heat exchangers of 160 MW generator located on each side of the stator. The simple and effective cooling system is slightly soiled, that significant assists to keep relatively low heat level of the active parts and the high effectiveness of the generator at the whole lifetime. Many design solutions for air-cooled turbogenerator were based on the reliable and proved by the long time service decisions realized before at the hydrogen-cooled generators of the similar class. Due to that, the “ELSIB” air-cooled generators imbibed all the best and proved existing today at the Russian generator technology. Moreover, they possess the unique capability to be transformed into hydrogen-cooled generator with the slight modernization fulfilled on site. At the same time the capacity of generator can be increased to 150 %. This gives the additional opportunities for our customers to plan the power system changes and reconstructions. The design and manufacturing technology of the generators guarantee the high maintainability of the equipment that at great extent reduces the possible future costs of our customers. Moreover, these generators with the minimum costs can be assembled on the existing foundations of the retired turbogenerators of the same capacity class with air and hydrogen cooling system. |
urbogenerators
with air-cooling system of “ELSIB” production are the
optimum choice for the power system application that demand
flexibility and simplicity of operation and service.
Liquid-cooled turbogenerators
|
S The liquid-cooled turbogenerators are well suited to central large power plants with power blocks of large output capacity. The requirements for a reliability and stable operation in the power grid of these generators are especially high. The liquid-cooled generators of ТВН type supplied by “ELSIB” are unique equipment without analogues in the world generator technology. The construction peculiarity is a filling of the stator volume with the heat resistance dielectric liquid that is also the cooling medium and a stator insulation system component (like in oil transformer). The dielectric liquid is circulated in a closed loop to remove the heat from the active elements of stator and cools at the water heat exchangers located out the case of the generator. The stator volume filled with the liquid is limited by the end shields, stator case, and from the side of a gap between stator and rotor - by the special dielectric cylinder. The insulation system of stator winding has the significantly more high dielectric strength than other known types of the insulation used at the large turbogenerators. This allows creating the generators with the optimum stator voltage in respect to the main parameters of the machine. The generator rotor is cooled by water supplied and drained through a water-fed device located at the central part of rotor shaft. The supply of cooling water to the rotor winding is provided with the radial units of the water-fed device. The
cooling and insulation systems of ТВН
generator give it the high reliability and provide a lot of the
advantages and unique operational properties. The sufficient
resources on the dielectric strength, heat loads, stability to the
mechanic influences at vibration and deformation of the stator
winding bars and other the design features allow to our customers
to achieve the significant saving of the means and be fully sure
in the reliable operation of these machines.
This happens mainly
due to the followings:
In comparison with the other generators of large capacity the TBH generators have simple design and production workability that provide the high reliability and durability at the relatively low costs. For design the TBH generators the hydraulic and thermal phenomena at ducts of core and stator and rotor windings on the models, samples and test platforms were investigated. The researches done with the special platforms and natural generators defined the design of the end conical packets of stator core, wedge area of rotor and other assemblies. |
olution
for the maximum loads
A turbo generator is a turbine directly connected to an electric generator for the generation of electric power. Large Steam powered turbo generators (steam turbine generators) provide the majority of the world's electricity and are also used by steam powered, turbo-electric ships.
UNIT 2. SPECIAL PURPOSE PLANTS AND MACHINES