JPH08210602A - Steam generator for heating sodium - Google Patents

Abstract

PURPOSE: To form respective heat transfer pipes with optimum materials meeting temperature conditions and lower a cost by using the heat transfer pipes made of different materials in a high-temperature steam outlet side and a low- temperature water feed side in a sodium heating steam generator used under high temperature. CONSTITUTION: In a sodium heating steam generator, the material of a helical coil type heat transfer pipe 1 is changed in its intermediate part so that the heat transfer tube is provided with the range of a heat resistant alloy in a high-temperature steam outlet side which is limited to a minimum range and a low-temperature water feed side of a liquid phase side made of a material conforming to general specifications. For example, for the heat transfer pipe in a steam outlet side near a sodium inlet side which becomes high temperature during operation of the steam generator, an improved 9Cr-1Mo steel high in its strength under the high temperature is used. For the low-temperature water feed side during operation of the steam generator, an inexpensive 21/4Cr-1Mo steel is used. Thus, the helical coil type heat transfer pipe 1 can maintain required strength during operation of the steam generator and the cost can be lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sodium heating steam generator having a heat transfer tube of spiral coil type or the like.

[0002]

2. Description of the Related Art As shown in FIG. 1, a steam generator for heating sodium has a helical coil type heat transfer tube 1 housed in a shroud 2 and an inner cylinder 3 and then in a cylindrical container 4. . Four to six water supply tube plates 6 are arranged on the lower mirror 5, and the helical coil heat transfer tube 1 is connected thereto. Similarly, a steam outlet tube plate 8 is arranged on the upper mirror 7 and is connected to the outlet side of the helical coil heat transfer tube 1, and the water flowing in the helical coil heat transfer tube 1 is heated by high temperature sodium to generate steam. Becomes

In the shell side sodium system, sodium enters from a sodium inlet nozzle 10 provided in the upper shell 9,
The structure is such that the distributor 11 supplies the heat to the upper part of the spiral coil type heat transfer tube 1 to perform heat exchange in the heat transfer tube part, and to exit from the sodium outlet nozzle 12 provided in the lower mirror,
The material of the spiral coil heat transfer tube 1 is made of a heat-resistant alloy that can withstand the temperature at the sodium inlet side (for example, improved 9Cr).
-1Mo steel etc.) is adopted.

[0004]

In a sodium heating steam generator such as a steam generator of a fast breeder reactor plant, there is a large temperature difference between the feed water side and the steam outlet side, and the steam outlet side arranged at the sodium inlet side. The design temperature of the heat transfer tube is very high, for example 520 ℃. In order to satisfy the strength required from the pressure inside the pipe under the condition of high sodium inlet temperature, the plate thickness of the pipe should be increased or an expensive heat resistant alloy with high high temperature strength (for example, improved 9Cr-1Mo steel etc.) ) Is required, but the heat transfer performance deteriorates as the plate thickness of the tube increases. Therefore, conventionally, the material of the tube was a heat-resistant alloy having sufficient strength at the sodium inlet temperature.

However, when the material of the tube is made of a heat-resistant alloy due to its strength at a high temperature sodium inlet and temperature, the strength becomes unnecessarily high on the low temperature side, which increases the manufacturing cost of the steam generator.

The present invention is intended to provide a steam generator for heating sodium which can solve the above problems.

[0007]

According to the present invention, in a sodium heating steam generator used at a high temperature, heat transfer tubes having different materials are used for a high temperature steam outlet side and a low temperature water supply side.

[0008]

According to the present invention, since the heat transfer tubes having the high heat resistance conditions are all different from each other, the heat transfer tubes having different materials are used for the high temperature steam outlet side and the low temperature water supply side. The degree of freedom in selecting the heat tube is increased, and the cost down can be achieved.

[0009]

EXAMPLE An example of the present invention will be described below. In this embodiment, in the sodium heating steam generator shown in FIG. 1, the material of the helical coil type heat transfer tube 1 is changed from the middle to keep the range of the high heat resistant alloy on the high temperature steam outlet side to the minimum range. The material of the low temperature part on the low temperature water supply side, which is the phase side, is the heat transfer tube of the general specification.

For example, improved 9Cr-1Mo steel, which has high strength at high temperature, is used for the heat transfer tube on the steam outlet side where the temperature becomes high during operation of the steam generator near the sodium inlet side. Due to the low temperature, it is cheap
2 1/4 Cr-1Mo steel is used.

As a result, the helical coil heat transfer tube 1 retains the required strength when the steam generator is in operation, and
It is possible to reduce costs.

[0012]

In the conventional sodium heating evaporator, all the heat transfer tubes are made of materials for the high temperature steam outlet side, which has the most severe conditions. However, in the present invention, the heat transfer tubes are provided on the low temperature water supply side. For example, by using inexpensive 2 1/4 -1Mo steel for the heat transfer tube, the range of using an expensive material that can withstand high temperature is kept to the minimum range and the optimum temperature condition for each part A heat transfer tube having the material Therefore, rational design and cost reduction can be achieved by the present invention.

[Brief description of drawings]

FIG. 1 is a structural diagram of a helical coil steam generator.

[Explanation of symbols]

 1 Helical Coil Type Heat Transfer Tube 2 Shroud 3 Inner Tube 4 Container 5 Lower Mirror 6 Water Tube Plate 7 Upper Mirror 8 Steam Outlet Tube Plate 9 Upper Body 10 Sodium Inlet Nozzle 11 Distributor 12 Sodium Outlet Nozzle

Claims (1)

[Claims] 1. A sodium heating steam generator for use in high temperatures, characterized in that heat transfer tubes made of different materials are used on a high temperature steam outlet side and a low temperature water supply side. vessel.