SU916770A1 - Exhaust pipe of steam turbine low-pressure end - Google Patents

Description

The invention relates to turbine construction and can be used in parts of low pressure (PND) steam turbines.

Known exhaust pipe part of the low pressure steam turbine, consisting of an axial diffuser, in which the main flow inhibition occurs, and a collection chamber, which collects steam and leads it to the condenser [1].

The complex asymmetrical nature of the flow in the nozzle, especially in the collecting chamber, leads to the fact that its losses account for a significant share in the total balance of losses of the exhaust path of the turbine.

The exhaust pipe of the low-pressure part of the steam turbine is known, which contains an axial radial diffuser located behind the working blades of the last stage and communicated with the collecting chamber consisting of the lower half and the cover (2).

The resistance of such nozzles monotonously decreases with an increase in their overall dimensions of ² dimensions. Therefore, to achieve the level of hydraulic losses corresponding to nozzles with guide ribs, the dimensions of the nozzles of this design are increased

so significant that their use in real-world turbine units is usually not possible.

The purpose of the invention is to reduce the hydraulic losses of the pipe.

This goal is achieved by the fact that the output diameter of the diffuser is (1.35 1.45) O _n , the width of the collecting chamber (2.35–2.6) _Η , and the height of the cover (0.9–1.1) E _n , where ϋ _Η is the peripheral diameter of the last stage.

FIG. 1 shows the scheme of the exhaust pipe; in fig. 2 is a view A of FIG. one.

The exhaust pipe PND of the steam turbine, installed after the last stage 1, consists of an axial diffuser 2 and a collecting chamber 3, which is structurally divided by a horizontal connector 4 into the upper and lower halves 5 and 6. The upper half 5 is structurally separated into a separate element — the nozzle cover ( camera assembly 3).

Diffuser outlet diameter 2 =

(1.35–1.45) ϋ _Η , width of the collecting chamber 3

B = (2.35–2.6), and the lid height is 5

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Н «р = (0.9-1.1) ϋκ, where Э _н is the peripheral diameter of the last stage 1 of the PND.

In the process of turbine operation, the steam leaving the last stage 1 PND gets into the axial radial diffuser 2, where the main braking of the steam flow occurs. After the diffuser 2, the steam enters the collecting chamber 3, from where it is sent to the turbine condenser.

The implementation of the exhaust pipe with the specified optimal ratios of its parameters makes it possible to reduce hydraulic losses without increasing the dimensions and complicating the design of the pipe. This is achieved by eliminating the axial asymmetry of the flow of steam in the diffuser, stagnant zones in the cover, not occupied by the active flow. _

In addition, the provision of these optimal ratios of the parameters of the exhaust pipe leads to a decrease in the coefficient of total losses of the pipe.

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Claims (1)

Claim The exhaust pipe of the low-pressure part of the steam turbine, which contains an axial radial diffuser, located behind the ₅ blades of the last stage and communicated with a collecting chamber consisting of the lower half and a cover, characterized in that, in order to reduce hydraulic losses, the diffuser outlet diameter is (1, 35–1.45) O _n , the width of the collecting chamber (2.35–2.6) _Η , and the height of the lid (0.9–1.1) E _n , where ϋ _Η is the peripheral diameter of the last stage.