Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D17/00—Regulating or controlling by varying flow
  • F01D17/10—Final actuators
  • F01D17/12—Final actuators arranged in stator parts
  • F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
  • F01D17/141—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D17/00—Regulating or controlling by varying flow
  • F01D17/10—Final actuators
  • F01D17/12—Final actuators arranged in stator parts
  • F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
  • F01D17/141—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path
  • F01D17/143—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path the shiftable member being a wall, or part thereof of a radial diffuser
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D17/00—Regulating or controlling by varying flow
  • F01D17/10—Final actuators
  • F01D17/12—Final actuators arranged in stator parts
  • F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
  • F01D17/16—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of nozzle vanes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D17/00—Regulating or controlling by varying flow
  • F01D17/10—Final actuators
  • F01D17/12—Final actuators arranged in stator parts
  • F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
  • F01D17/16—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of nozzle vanes
  • F01D17/165—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of nozzle vanes for radial flow, i.e. the vanes turning around axes which are essentially parallel to the rotor centre line
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D17/00—Regulating or controlling by varying flow
  • F01D17/10—Final actuators
  • F01D17/12—Final actuators arranged in stator parts
  • F01D17/18—Final actuators arranged in stator parts varying effective number of nozzles or guide conduits, e.g. sequentially operable valves for steam turbines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/12—Blades
  • F01D5/14—Form or construction
  • F01D5/141—Shape, i.e. outer, aerodynamic form
  • F01D5/146—Shape, i.e. outer, aerodynamic form of blades with tandem configuration, split blades or slotted blades
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D9/00—Stators
  • F01D9/02—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles
  • F01D9/04—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector
  • F01D9/041—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles forming ring or sector using blades
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2220/00—Application
  • F05D2220/30—Application in turbines
  • F05D2220/31—Application in turbines in steam turbines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2240/00—Components
  • F05D2240/10—Stators
  • F05D2240/12—Fluid guiding means, e.g. vanes
  • F05D2240/121—Fluid guiding means, e.g. vanes related to the leading edge of a stator vane
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2250/00—Geometry
  • F05D2250/90—Variable geometry
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2270/00—Control
  • F05D2270/01—Purpose of the control system
  • F05D2270/17—Purpose of the control system to control boundary layer
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2270/00—Control
  • F05D2270/30—Control parameters, e.g. input parameters
  • F05D2270/301—Pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2270/00—Control
  • F05D2270/30—Control parameters, e.g. input parameters
  • F05D2270/306—Mass flow

Definitions

• This invention relates to a control diaphragm of a steam turbine.
• the control diaphragm is a device used to control the pressure in a controlled extraction. Its task is to maintain the pressure in the wide range of operating modes when the amount of extracted steam and thus the amount of steam passing through the flow path of the turbine downstream of the extraction also changes.
• Controlled extraction i.e. the extraction of steam from the flow path of the turbine, is carried out e.g. in district heating plant turbines where the extraction heats the heating water heaters.
• the outlet temperature from the heater is dependent on the extraction pressure and must be maintained even with a very variable amount of heated water and thus also the amount of steam taken from the turbine.
• Maintaining the desired pressure in the extraction with changing flow rate is a technical problem.
• the amount of medium flowing into the flow path in the direction of the main flow downstream of the extraction also changes, which leads to the fact that, according to the laws of physics, the pressure in the extraction changes, and therefore it is necessary to add a control body for the extraction, which will limit pressure fluctuations in the extraction.
• This is achieved by adapting the flow area of the control body to the residual flow downstream of the extraction.
• a control seat valve or seat valves that can be closed and opened as needed, can be used.
• Other possible solutions are control flaps or slide valves.
• control diaphragm A special case of a rotary slide valve is the control diaphragm.
• the control diaphragm is also made up of a fixed and a rotatable part.
• the fixed and rotatable part are formed by parts of the stage stator blade row, the blades of which are cut into two parts:
• Control diaphragms are known for both axial and radial, and also for radial-axial stages.
• the blades are cut by a plane perpendicular to the axis of the diaphragm.
• the blade row is cut into two parts by a cylindrical surface with an axis identical to the axis of the diaphragm.
• the medium When the flow area in the control body is reduced due to pressure control in the extraction, the medium must accelerate significantly in the reduced cross-section.
• a large cross-section dimensioned for maximum flow follows further downstream (e.g. a pipe downstream of a seat valve or flap). In it, the flow slows down again, which usually means the conversion of a large part of the kinetic energy into heat, which can no longer be used for mechanical work. This process is called throttling and the loss associated with it is called throttling loss.
• the control diaphragm has a narrowed area in the stator blade row, which is very close to the rotor blade row.
• the steam flow thus loses only a small part of its kinetic energy, and it is immediately directed in the required circumferential direction by the trough side (pressure side) of the fixed part of the stator. Due to inertia, it then reaches the rotor blades, which convert the kinetic energy into mechanical work.
• the control diaphragms have better efficiency than other throttling control bodies. Compared to other control bodies, the control diaphragm also takes up less space in the axial direction, because it connects directly to the flow path at its inlet and outlet and it also functions as a part of the turbine stage itself. If the pressure at the extraction point is controlled by a seat valve or flap, there must be space to bring the steam to the seat valve/flap and then to take it back to the flow path.
• Such a standard design of the diaphragm has a minimal loss at full opening, when the rotatable and the fixed part of the stator grid connect to each other.
• losses occur on the route between throttling and the rotor blades.
• the flow In the partially open state, the flow separates downstream of the leading edge, and the resulting vortices are then transferred to the rotor blade row and to other stages and significantly reduce the efficiency of the turbine, see e.g. Lampart P., Puzyrewski R., Numerical analysis of adaptive control in LP turbines, TASK Quarterly, vol. 9, No. 2, pp. 211 - 234, 2005.
• control stage connected to the seat valves has a higher efficiency under partial load in the vicinity of the valve points than a partially open control diaphragm.
• a multivalve arrangement may be more advantageous than the known control diaphragm.
• the aim of this invention is therefore to improve the design of the control diaphragm in such a way as to improve its efficiency in a partially open state, to also enable nozzle governing if possible, and at the same time to make its design simple and trouble-free.
• the circumferential width of the fixed parts of the blades is n times the width (c) of the channels plus eventual overlap (p), where n is a natural number greater than 1.
• the width (c) of the channels in this text will always denote the width of the channel at the fixed part inlet.
• the leading edges of the blades of the rotatable part are of n different types, while the leading edges of all following types are arranged: the first type, having a width (bi) which is the same as the width of the fixed parts of the blades, the second type (b?), having a width (n-1) times the width (c) of the channels between the fixed parts of the blades plus eventual overlap (p), and so on, up to the nth type, having a width (b n ) equal to the width (c) of the channels between the fixed parts of the blades plus eventual overlap (p).
• Optimal closure will thus occur in the state after turning in the direction of rotation of the rotatable part when closing by n*c+p/2, however, the diaphragm is fully closed at any turning from n*c to n*c+p.
• the overlap p thus represents a kind of dimensional margin preventing leaky closure in case of inaccurate turning of the rotatable part of the control diaphragm or in case of its inaccurate misalignment with respect to the fixed part.
• leading edges of the blades of the rotatable part according to the invention are distributed in such a way that
• all the leading edges (2) are, with their sides that are backward in the direction of rotation of the rotatable part during closing, in alignment with the edges of the respective fixed parts (1) (i.e. they align smoothly with them) and all channels are open,
• leading edges of the second type are, with their sides that are frontal in the direction of rotation, in alignment with the edges of the corresponding fixed parts (1),
• the leading edges of the possible third type are, with their sides that are frontal in the direction of rotation, in alignment with the edges of the corresponding fixed parts (1), and so on, until
• Opening takes place analogously gradually in the opposite order when turning in the opposite direction.
• the diaphragm can be adjusted to the flow rate at which the highest efficiency is needed.
• Different leading edges can advantageously be arranged alternately, for example one by one of each type, or with different numbers of leading edges of different types, or they can be arranged in larger groups, which makes it possible to have undisturbed flow and smaller losses at least in part of the stage circumference (then it is necessary to create a sufficiently large gap between the stage with the diaphragm and the stage downstream of it in the direction of the steam flow, so that, when partially opened, the steam flow from the group of open channels can flow into space downstream of closed channel groups).
• This de facto makes it possible to use the advantages of nozzle or group governing even in the case of a control diaphragm, and the solution according to the present invention thus combines the advantages of these two known solutions.
• the leading edges of the first type have the width of the fixed parts of the blades
• the leading edges of the second type have the width of the channels (plus eventual overlap p).
• n 3, i.e. the width of the fixed parts of the blades is three times the width of the channels between these blades (plus eventual overlap p), the leading edges of the first type have the width of the fixed parts of the blades, the leading edges of the second type have a width twice the width of the channels (plus eventual overlap p), and the leading edges of the third type have the width of the channels (plus eventual overlap p).
• This embodiment has the advantage that two partial closure modes are available, in which a part of the channels is completely closed and the remaining part of the channels is completely open. It is thus possible to propose two optimized modes of partial closure of the control diaphragm.
• n can be even higher, but with a higher value of n, the channels shrink quickly, and such systems have an optimal operating mode or modes only with larger steam extractions upstream of the diaphragm.
• Fig. 1 longitudinal section of an axial stage with a control diaphragm
• Fig. 2 one embodiment of the diaphragm according to the invention for an axial stage, in an unfolded partial section through a cylindrical surface with an axis identical to the axis of the diaphragm, in the fully open position,
• Fig. 3 diaphragm from fig. 2, in an unfolded partial section through a cylindrical surface with an axis identical to the axis of the diaphragm, in the partially open position.
• Fig. 4 diaphragm from Fig. 2, in an unfolded partial section through a cylindrical surface with an axis identical to the axis of the diaphragm, in the fully closed position,
• Fig. 5 another embodiment of the diaphragm according to the invention for the axial stage, in an unfolded partial section of a cylindrical surface with an axis identical to the axis of the diaphragm, in the fully open position,
• Fig. 6 another embodiment of the diaphragm according to the invention for an axial stage, in an unfolded partial section through a cylindrical surface with an axis identical to the axis of the diaphragm, in three different positions, from top to bottom: fully open, partially open and closed, and Fig. 7 longitudinal section of a radial-axial stage with a control diaphragm with a radial blade row.
• Fig. 1 shows a partial longitudinal section of an axial stage with a control diaphragm.
• the blade profiles are made up of two parts: the fixed parts 1, which are firmly connected to the stator, and the leading edges 2.
• the leading edges are connected by two rings 3, 4 at the hub and at the tip, forming a grid that can rotate with respect to the fixed parts 1.
• a partial section through the cylindrical surface with an axis identical to the axis of the diaphragm according to Fig. 2 to 6 is taken in one selected place of the control diaphragm between the two rings 3, 4 at the hub and at the tip.
• the shape of the blades is usually not constant along their entire length, the profiles on the smaller inner diameter are usually axially and circumferentially smaller than the profiles on the larger outer diameter, in order to compensate for the blades pitch which is proportional to the diameter.
• the dimensions ratios designed according to this invention are preferably applicable to all positions of the cylindrical surface between the two rings 3, 4 on the hub and on the tip.
• the channels between the leading edges are also of two types - those adjacent to the suction sides of the wider leading edges have the same width as the channels between the fixed sections of the profiles, while those adjacent to the suction sides of the narrower leading edges have a width equal to double width of the channel between the fixed parts of the profiles.
• the blade profile of the diaphragm therefore has, in the plane of cutting into the fixed and rotatable part, a thickness slightly greater than 2/3 of the pitch. Less than 1/3 of the pitch remains for the inter-blade channel. This is best seen by comparing Figures 2 and 4.
• the control diaphragm is optimized for this flow rate. By choosing the number of leading edges of these two types and grouping them, it is possible to adapt this flow rate to the most likely operating mode of the steam turbine. Only during further closing process will the narrow leading edges 2b begin to close the remaining channels and gradually the diaphragm will be completely closed (Fig. 4).
• Fig. 5 shows another advantageous embodiment, which includes three different types of leading edges (n - 3).
• the channels adjacent to the remaining types of leading edges 2b and 2c are still fully open.
• This position represents the first optimal mode of partial closure of the control diaphragm.
• the channels adjacent to the leading edges 2c are still fully open.
• This position represents the second optimal mode of partial closure of the control diaphragm.
• This second embodiment thus enables optimization for multiple operating modes.
• the price for this is a relatively (compared to the width of the inter-blade channels) larger circumferential width (of fixed parts) of the blades. Therefore, they have worse properties of the diaphragm in a completely open state, and optimal operating modes are only achieved with larger steam extractions upstream of the diaphragm.
• Fig. 6 shows another advantageous embodiment according to claim 3.
• the leading edges of the same type are arranged in groups. There can be one such group or more groups from each type of leading edge on a wheel.
• the number of leading edges in the group again allows the design of the control diaphragm to be adapted to the customer's requirements for flow rates through the diaphragm in operations important to him.
• This arrangement is advantageous in operations where there are open channels downstream of one type of leading edges and closed channels downstream of an adjacent type of leading edges. Through the gap between the stator and rotor blades, the spaces downstream of the group with open channels are connected to the space downstream of the closed channels only at the fringes of the open group (or groups).
• leading edge (of the first type, or wide leading edge)

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Turbine Rotor Nozzle Sealing (AREA)

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• 2023
  • 2023-12-13 CZ CZ2023-484A patent/CZ310425B6/cs unknown
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