JPH0116881Y2 - - Google Patents

Description

[Detailed Description of the Invention] In the present invention, a heating medium flows into the inner shell through an annular gap formed between the inner shell and the shell, and the heated medium flows through a large number of heat transfer tubes in the inner shell. The present invention relates to an improvement in a steam generator in which, after heat exchange, the steam flows out into an annular gap separated from the annular gap.

To explain the outline of the steam generator with reference to FIG. 1, the heating medium that flows in from the inlet nozzle 3 in the direction of arrow A flows into the annular gap 10 and passes through the inflow window 5 provided around the upper part of the inner shell 2. It flows into the inner shell 2. The heating medium that has flowed in this way is transferred to the inner shell 2.
The heat exchanger flows down as shown by the arrow while exchanging heat with the medium to be heated (water that flows in from the water nozzle 7 and enters the heat transfer tubes 6 as shown by arrow C) flowing through the large number of heat transfer tubes 6 disposed inside. It flows out into the annular gap 10' through the outflow window 5' provided on the lower circumferential surface of the inner shell 2, and flows through the outlet nozzle 4.
It flows out as shown by arrow B. The medium to be heated flowing through the heat transfer tube 6 changes into steam through heat exchange with the heating medium and flows out from the steam nozzle 8 as shown by the arrow.

The inflow and outflow of the heating medium is carried out by an inflow nozzle 3 and an outflow nozzle 4 provided on one outer surface of the shell 1, so that the inflow into the inner shell 2 and the outflow from the inner shell 2 become uneven flows. Affecting the heat load on the heat exchanger tubes 6 and reducing heat exchange efficiency, or causing a difference in thermal expansion between the heat exchanger tubes 6, causing thermal deformation of the steam generator or inducing breakage of the heat exchanger tubes 6. become. In order to prevent this uneven flow of the heating medium, uniform flow rate plates 9, 9' are conventionally provided on the outer peripheral surface of the inner shell 2, as shown in the figure, within the annular gaps 10, 10'.

By the way, as shown in FIG. 2, the flow of the heating medium in the annular gap 10 generates a vortex behind the uniform flow rate plate 9, so that a phenomenon occurs in which the uniform flow rate plate 9 vibrates. To explain this phenomenon in more detail, the heating medium flowing in from the inlet nozzle 3 in FIG. Behind the uniform flow rate plate 9, the flow separates from the plate and a strong vortex is generated behind the plate. In this vortex region, the flow velocity repeatedly fluctuates irregularly over time, and accordingly, the fluid pressure applied to the flow rate uniform plate 9 also fluctuates irregularly. As a result, vibration occurs in the flow rate uniformity plate 9, and this vibration causes cracks in the joint between the inner shell 2 and the flow rate uniformity plate 9, which may lead to corrosion or other accidents. Furthermore, the same problem may occur with respect to the flow rate uniform plate 9' within the annular gap 10'.

The present invention has been developed to solve these problems, and includes a flow rate uniform plate shaped so that no vortex of the heating medium is generated behind the flow rate uniform plate, and vibration is not generated in the flow rate uniform plate. The aim is to provide a steam generator with

FIG. 3 shows an embodiment of the steam generator of the present invention, in which a large number of holes 11 are bored in flow rate uniform plates 9, 9'. In this embodiment, the heating medium flowing from the inlet nozzle 3 flows into the annular gap 10,
It rises while filling the annular gap 10, and uniformly flows into the inner shell 2 through each inflow window 5. During the process in which the heating medium rises while filling the annular gap 10 in this manner, a portion of the heating medium passes through the holes 11 formed in the flow rate uniform plate 9 as shown in FIG. By forming a slight upward flow behind the flow rate uniformity plate 9 by this passage, the flow rate uniformity plate 9
No eddy current is generated behind the flow rate uniform plate 9, and vibration of the flow rate uniform plate 9 is no longer generated. In this case, the total passage area or passage resistance of the holes 11 is such that the flow of the heating medium into the inner shell 2 does not cause uneven flow, and the flow rate uniformity function is not impaired.

On the other hand, at the outlet portion, the heating medium that has similarly flowed out into the annular gap 10' from the outflow window 5' rises while filling the annular gap 10, and flows out from the outlet nozzle 4. In the process in which the heating medium rises while filling the annular gap 10', a portion of the heating medium flows through the hole 11 formed in the flow rate uniform plate 9'.
pass through. By forming a slight upward flow behind the uniform flow rate plate 9' due to this passage, no vortex is generated behind the uniform flow rate plate 9', and vibration of the uniform flow rate plate 9' is prevented. in this case,
The total passage area or passage resistance of the holes 11 is such that the outflow of the heating medium from the inner shell 2 to the annular gap does not cause uneven flow, so that the flow rate equalization function is not impaired.

As detailed above, the steam generator of the present invention has a large number of holes bored in the circumferential direction with an outer diameter smaller than the inner diameter of the shell on the outer circumferential surface of the inner shell within the annular gap near the inflow and outflow portions of the heating medium. Since the annular flow uniformity plate is provided, the vortex behind the flow rate uniformity plate caused by the flow of the heating medium is eliminated, and vibrations of the flow rate uniformity plate and the joint between the inner shell and the flow rate uniformity plate due to vibration are eliminated. This has the effect of preventing cracks, corrosion, and other accidents from occurring.

[Brief explanation of drawings]

Fig. 1 is a schematic longitudinal sectional view of a conventional steam generator, Fig. 2 is an enlarged longitudinal sectional view of main parts showing the flow of the heating medium inlet in the conventional steam generator, and Fig. 3 is a schematic longitudinal sectional view of a conventional steam generator. This shows the uniform flow rate plate at the inflow and outflow portions of the heating medium in the generator, and is indicated by X in Figure 1.
- A cross-sectional view corresponding to the X cross section and the YY cross section,
FIG. 4 is an enlarged longitudinal cross-sectional view of a main part showing the flow state of the heating medium inlet in the steam generator of the present invention. 1... Shell, 2... Inner shell, 3... Inlet nozzle, 4... Outlet nozzle, 5... Inflow window, 5'...
Inflow window, 6... Heat exchanger tube, 9, 9'... Flow rate uniform plate,
10, 10'... annular gap, 11... hole.

Claims (1)

[Scope of utility model registration request] The heating medium flowing from the inlet nozzle flows into the inner shell through the annular gap between the inner shell and the shell, and after exchanging heat with the medium to be heated flowing through a large number of heat transfer tubes in the inner shell, In a steam generator in which the steam flows out from the outlet nozzle through an annular gap separated from the gap, an outer diameter smaller than the inner diameter of the shell is provided on the outer peripheral surface of the inner shell within the annular gap near the inflow/outflow portion of the heating medium. A steam generator characterized by having an annular flow rate uniform plate with a large number of holes bored in the circumferential direction.