JPH0229423Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a high temperature heat exchanger.

[Conventional technology]

In recent years, heat generated in high-temperature heating furnaces (e.g., nuclear reactors) is extracted using a heat medium such as helium gas, and this is exchanged with a secondary heat medium in an intermediate heat exchanger.
The heat obtained here is used to generate electricity.

An example of the structure of a heat exchanger used in this high-temperature heating furnace will be explained with reference to FIG. A primary heat medium inlet 2 is formed to introduce a high temperature primary heat medium obtained from a heat exchanger (not shown) into the container 1. The high-temperature primary heat medium introduced into the container 1 from the primary heat medium inlet 2 flows between the helical coils 3 in the container 1 in which the helical coils 3 each having multiple cylindrical heat transfer tubes are provided. The primary heat medium that has risen and reached the top descends through the flow path 5 formed between the inner surface of the container 1 and the outer surface of the partition wall 4, and is finally formed at the lower side of the container 1. The heat medium is discharged from the primary heat medium discharge port 6 and transferred to the high temperature heating furnace again.

On the other hand, the helical coil 3 is formed in a spiral shape around a center pipe 7 provided along the axial direction of the central part of the container 1, and one end of the helical coil 3
is connected to a secondary heat medium inlet 8 formed at the top end of the center pipe 7 via an upper connecting pipe 9 and an inflow header 10, and the other end is connected to the lower end of the center pipe 7 by an outflow lower connecting pipe 11. Therefore, the low-temperature secondary heating medium introduced from the secondary heating medium inlet 8 passes through the upper connecting pipe 9 and then flows down inside the helical coil 3 while exchanging heat with the primary heating medium. Then, it flows into the lower end of the center pipe 7, rises therein, and is transferred to other devices through the secondary heat medium outlet 12 at the upper end. 1 in the diagram
3 is a heat insulating material provided on the outer periphery of the container 1 so as to surround it; 14 is a heat insulating material provided on the inner surface of the partition wall;
5 indicates a tube support beam.

In the above configuration, conventionally, the radial pitch of the heat transfer tubes constituting the helical coil is the same, so in this case, the outer layer has a larger diameter, so the flow passage cross-sectional area is larger than the inner layer, and the outer layer has a larger diameter than the inner layer. Unbalanced flow of the primary heating medium occurs. As a result, an imbalance between heat collection and heat exchange may occur, in which case no improvement in thermal efficiency can be expected, and there may be adverse effects such as a partial increase in the heat exchanger tube metal temperature.

[Problem that the invention attempts to solve]

This invention prevents drifting of the primary heat medium outside the tube,
This aims to adjust the heat absorption balance with respect to heat exchange and improve thermal efficiency.

[Means for solving problems]

The present invention is a heat exchanger in which a helical coil consisting of concentrically arranged cylindrical heat transfer tubes is housed in a hollow cylindrical container, and a heat medium rises outside the helical coil. A heat transfer accelerator plate is inserted between each helical layer, and the thickness of the heat transfer accelerator plate is gradually increased from the inner layer to the outer layer.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

In this embodiment, the pitch in the radial direction of the heat transfer tube is made smaller toward the outer layer, and the thickness of the heat transfer promoting plate is gradually increased.

In the high temperature heat exchanger according to this embodiment, in order to improve the heat exchange performance of the three helical coil sections, a cylindrical and flat heat transfer promoting plate 16 as shown in FIG. 2 is provided between the three helical coil layers. There is. The heat transfer accelerator plate 1
6 is a heat transfer tube 17 that transfers the heat of the primary heat medium by radiant heat.
However, since the helical coil is inserted between each layer, by gradually increasing the thickness of the heat transfer accelerator plate 16 toward the outer layer, the cross-sectional area of the flow path outside the tube of the helical coil layer increases as the outer layer increases. It is possible to reduce the rate of increase in , thereby correcting the thermal imbalance in the flow rate of the extratubular primary heat medium between the inner and outer layers.

Furthermore, since the weight of each heat transfer tube 17 is supported by a ladder-like tube support device 20 (see FIG. 3) suspended from the tube support beam 15, the radial direction of the tube support device 20 is The radial pitch of the heat exchanger tubes 17 can be varied by varying their dimensions depending on their location. By gradually decreasing the pitch in the radial direction toward the outer layer, it is possible to reduce the rate of increase in the cross-sectional area of the extra-tube flow path between the helical coil layers as the outer layer increases, and as mentioned above, the thickness of the heat transfer accelerator plate can be reduced. Coupled with the effect of changing the temperature, it is possible to correct the thermal imbalance in the flow rate of the extra-tube primary heat medium between the inner and outer layers.

In addition to the above-mentioned methods, by reducing or increasing only the thickness of the heat transfer accelerator plate or the pitch in the radial direction of the heat transfer tube toward the outer layer, it is possible to It is possible to correct the thermal imbalance, and it is possible to prevent an imbalance between heat absorption and heat exchange. That is, between each coil layer, a heat balance as shown in the following equation is established.

G _i (1)C _p (1){T _i ^O (1)−T _i ^I (1)} =N _i G ₂ (2)C _p (2){T _i ^I (2)−T _i ^O ( 2)}=... G(1)= 〓 ⁱ G _i (1)... G(2)= 〓 ⁱ G ₂ (2)・N _i ... (i=1, n) Also, the flow rate between each Hercal layer The balance is K _i V _i ² = K _i+1 V _i+1 ² ... (i=1, n-1) V _i = G _i /ρA _i ... (i=1, n) Symbol/G: Flow rate C _p : Fluid specific heat T ^O : Outlet temperature T ^I : Inlet temperature N: Number of heat transfer tubes G ₂ : Flow rate per heat transfer tube n: Number of coil layers K: Friction coefficient V: Flow velocity ρ: Density A: Flow path disconnection Area subscript/i: i-th layer coil (1): outside the pipe (2): inside the pipe , From the formula, determine G _i so that T ^O _i (1) = T _{i +1} ^O (1), and from this , the pitch in the radial direction of the heat transfer tube or the thickness of the heat transfer accelerator plate may be changed so that K _i and A _i satisfy this equation.

[Effects of the invention] As described above, according to the present invention, the uneven flow of the heat medium outside the tube is prevented, so the heat absorption balance of the fluid inside the tube is maintained, the heat exchange efficiency is improved, and the temperature of the heat transfer tube metal is reduced. It is possible to eliminate negative effects such as an increase in

[Brief explanation of the drawing]

Figure 1 is a vertical sectional view showing an example of a heat exchanger;
The figure is a partial explanatory view showing an example of a heat transfer accelerator plate, and FIG. 3 is an explanatory view of a tube support device. 1 is a container, 3 is a helical coil, 16 is a heat transfer accelerator plate, 17 is a heat exchanger tube, and 20 is a tube support device.

Claims (1)

[Scope of utility model registration request] In a heat exchanger, a helical coil composed of concentrically arranged cylindrical heat transfer tubes is housed in a hollow cylindrical container, and a heat medium rises outside the helical coil. A heat exchanger characterized in that a heat transfer accelerator plate is inserted between each helical layer, and the thickness of the heat transfer accelerator plate is gradually increased from the inner layer to the outer layer.