JPS603637B2 - air cooler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air cooler in an auxiliary core cooling system of a liquid metal fast breeder reactor. The present invention relates to an air cooler in which there is no fear of local blockage and the temperature of the coolant can be easily controlled.

The auxiliary core cooling system of the fast breeder reactor is a decay heat removal device after reactor tribbing, which is shown as a whole by reference numeral 1 in Figure 1, and is on standby when the auxiliary reactor D cooling system is not operating, that is, when the plant is operating at normal output. It is in driving condition. In this standby operation state, the blower 3 of the air cooler 2 is stopped, and the inlet vane 4, inlet damper 5, and outlet damper 6 of the blower 3 are fully opened, but liquid sodium etc. A small amount of coolant is distributed. On the other hand, even in the standby operation state of the auxiliary core cooling system 1, leakage air exists in the air cooler 2 due to natural circulation force, and this leakage air removes heat from the coolant. The flow rate is determined so that the coolant outlet temperature of the air cooler 2 does not fall below the solidification temperature of the coolant.

Viewed from the opposite perspective, this indicates that unnecessary heat removal is being performed by the leakage air, resulting in heat loss in the plant. This amount of heat loss varies depending on the structure of the air cooler, but is generally about 5% of its rated heat removal capacity, which may correspond to about 0.3% of the plant heat output. In addition, during standby operation of the auxiliary core cooling system 1, since both the air volume and the coolant flow rate are small, a deviation occurs in the flow distribution of these, and the heat transfer tubes 7 are locally supercooled.
Not only is there a risk of local blockages, but the response of the air cooler outlet coolant temperature to changes in the ratio of air volume to coolant flow rate is very slow and difficult to control.

SUMMARY OF THE INVENTION Therefore, the purpose of the present invention is to eliminate the various inconveniences mentioned above, to reduce heat loss in the standby operation state of the auxiliary core cooling system, to eliminate the possibility of local blockage of heat transfer tubes, and to control the outlet coolant temperature. It is easy to provide an air cooler.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 20 indicates the entire air cooler according to the present invention, and this air cooler 20 includes an air passage 8 and a blower 3.
and a recirculation air passage 9.

The air passage 8 is a vertical cylindrical body with an enlarged central portion, and inlet and outlet dampers 5 and 6 are provided near the closed lower end and the open upper end, respectively, and in the expanded central portion, A heat exchanger tube 7 with cooling fins 10, 10 is provided.

The heat exchanger tube 7 is connected to an intermediate heat exchanger 13 (see FIG. 1) via tubes 11 and 12 to the inlet and outlet coolant. A blower 3 is connected to the lower end of the air passage 8.

This blower 3 includes an inlet vane 4 for adjusting air volume. Further, a recirculation air passage 9 is attached to the outside of the air passage 8 so as to bypass the heat exchanger tube 7. One end (upper end) of this recirculation air passage 9 is connected to a portion between the outlet damper 6 of the air passage 8 and the heat transfer tube 7, and its lower end is connected to the inlet damper 5 of the air passage 8. It is connected to a recirculation air ring header 14 provided to surround the part between the heat pipe 7 and the heat pipe 7 . A small-capacity recirculation blower 15 is provided in the middle of the recirculation air passage 9.

The recirculation blower 15 operates to suck in high-temperature air in the air passage 8 from the closed upper end of the recirculation air passage 9 and feed it to the recirculation air ring header 14 . A recirculation inlet damper 16 is provided on the inlet side of the recirculation blower 15. Meanwhile, a plurality of recirculating air nozzles 17, 17 are connected to the inner surface of the recirculating air ring header 14.

The inner end of the recirculating air nozzle 17 passes through the side of the air passage 8 and closes into the air passage 8. In the illustrated embodiment, the inner end of each recirculated air nozzle 17 is bent such that the inner end closure faces diagonally upward. Therefore, the high-temperature air ejected from the recirculating air nozzles 17, 17 into the air duct 8 intersects within the air duct 8, as shown by dotted lines in FIG. 2, and intersects with each other. The air cooler 20 configured as described above is connected in parallel with the superheater 18 and the evaporator 19 with respect to the intermediate heat exchanger 13, similar to the conventional air cooler 2 shown in FIG.

In addition, in FIG. 1, numeral 21 indicates a fast breeder reactor, and numeral 2
2 is a primary main circulation pump, 23 is a secondary main circulation pump, 24 is a turbine, 25 is a generator, 26 is a feed water pump, 27 is a feed water heater, and
Reference numeral 28 indicates a coolant flow valve. This coolant flow control valve 28 is for adjusting the flow rate of coolant inside the heat transfer tube 7 . As described above, in the air cooler 2 according to the present invention, in its standby operation state, the blower 3 is stopped and the inlet vane 4, inlet damper 5, and outlet damper 6 are completely closed. Further, the recirculation blower 15 is in operation, and the opening degree of the coolant flow control valve 28 is set so that the flow rate of the coolant flowing inside the heat transfer tube 7 is minute.

During this standby operation, the high-temperature air moved by the leak air and passed through the heat transfer tube section is sucked into the recirculation air passage 9 by the recirculation blower 15, passes through the recirculation air ring header 14, and is recirculated. Air is ejected from the air nozzles 17, 17 to the lower part of the heat exchanger tube.

At this time, the plurality of high temperature air streams ejected from the plurality of recirculation air nozzles 17, 17 cross each other and are damaged.
The rising air with a uniform temperature distribution returns to the heat exchanger tube 7.
come into contact with. Note that by adjusting the opening degree of the recirculation inlet damper 16, the temperature of the coolant at the outlet of the air cooler can be adjusted. When the auxiliary furnace 0 cooling system 1 is in operation, that is, during emergency heat removal operation, the recirculation blower 15 is stopped and the recirculation inlet damper 16 is fully closed. In addition, the coolant flow section valve 28
The relationship between is set so that the flow rate of the coolant in the heat transfer tube 7 becomes the rated flow rate, and the relationship between
The blower 3 starts operating with the air blower 6 fully closed. The outside air introduced into the air cooler 20 by the blower 3 is blown against the heat transfer detector and exchanges heat with the coolant 7, and the heated airflow passes through the outlet damper 6 and enters the atmosphere. released.

Therefore, the coolant inside the heat exchanger tubes is air-cooled and the necessary amount of heat is removed. At this time, the temperature of the coolant at the outlet of the air cooler can be controlled by adjusting the opening degree of the inlet vane 4 of the blower. As is clear from the above description, the present invention provides an air cooler with a recirculation air passage, so that during standby operation, high-temperature air that has passed through the heat transfer tube section is recirculated below the heat transfer tube. Therefore, compared to conventional air coolers, much less hot airflow leaks through the outlet damper and is released into the atmosphere, significantly improving heat loss.

The power of a recirculating blower is a tenth of that of a blower, so it hardly matters. Furthermore, since high-temperature air is always blown onto the heat exchanger tubes, problems such as local blockage due to local overcooling do not occur.

Furthermore, since the outlet coolant temperature of the air cooler is controlled, unlike conventional air coolers, the coolant flow rate cannot be adjusted;
Since the recirculation air volume is adjusted while keeping this constant, changes in the outlet coolant temperature due to changes in the coolant temperature distribution in the heat transfer tubes do not occur, and the coolant outlet temperature changes in response to changes in the recirculation air volume. Coupled with the slow response to changes, there are various effects such as no oscillations in the coolant outlet temperature and control becomes very easy.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a power generation plant using a fast breeder reactor, and FIG. 2 is a diagrammatic sectional view of an air cooler according to an embodiment of the present invention. 2...Air cooler, 3...Blower, 5...
...Inlet damper, 6...Outlet damper, 7...Heat transfer tube, 8...Air duct, 9...Recirculation air duct, 14...Recirculation Air ring header, 15...
... recirculation blower, 16 ... recirculation inlet damper, 17 ... recirculation air nozzle, 20 ...
・Air cooler. Many 1. Figure 2

Claims (1)

[Scope of Claims] 1. An air duct that houses a heat transfer tube through which a coolant flows, an inlet and an outlet damper provided on the inlet and outlet sides of the air duct with respect to the heat transfer tube portion of the air duct, and A recirculation air passage that bypasses the heat exchanger tube is provided between the entrance and exit damper of the air passage, and the high temperature on the exit side than the heat exchanger tube part is provided during standby operation. An air cooler that recirculates air to the inlet side of the heat transfer tube section. 2. The air cooler according to claim 1, further comprising a recirculation blower and a recirculation inlet damper in the recirculation airway. 3. The high-temperature air jetting end of the recirculation airway is connected to a recirculation air ring header provided to surround the airway and the inner surface of this recirculation air ring header, and the inner end penetrates the side surface of the airway. 3. An air cooler according to claim 1, wherein the air cooler is connected to the air duct via a recirculating air nozzle opening into the air duct.