JPS6126722Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat exchanger for a boiler that can be applied to a device that is cooled midway through a downward flow or an upward flow.

As shown in Figure 8, when the flow rate in the tube decreases, that is, the load decreases, the heat transfer surface wall (used for the rear flue peripheral wall of the boiler) formed by the conventional downward flow in the boiler is affected by buoyancy. In some cases, the flow within the pipe was obstructed, leading to overheating failure, or due to the difference in thermal expansion, excessive stress was generated in the restraint part, leading to failure.
In Fig. 8, 1 is the inlet header, 2 is the outlet header, 3 is the inside of the flue, 4 is the heating flow, 5 is the flow direction,
6 indicates a wall tube composed of a plurality of heat exchanger tubes.

The present invention was proposed in order to eliminate the above-mentioned conventional drawbacks, and by providing a flow rate adjustment device at the inlet of the heat exchanger tube and communicating the heat exchanger inlet and outlet with a bypass pipe equipped with a valve. It is an object of the present invention to provide a heat exchanger for a boiler that can prevent the flow in the pipes from being inhibited by buoyancy even when the flow rate in the pipes decreases.

The embodiment of the present invention will be explained below with reference to the drawings. Figure 7 is a piping diagram of a heat exchanger showing an embodiment of the present invention. , the flow rate adjustment device 9 (FIGS. 1 to 6), the heater tube 10, the outlet header 11, and the flow,
Proceed to next step (eg superheater).

In addition, since the flow is unstable in a high flow rate region, only the flow rate necessary to protect the heater tube 10 is applied to the header 8.
Flow rate regulator 9, heater tube 10, outlet header 11
The remaining water is led to the outlet header 11 through the bypass pipe 12. Note that the bypass flow rate is adjusted by the valve 13. In addition, 14 in FIG. 7 is inside the flue, and 15 is outside.

Next, the flow rate adjusting device 9 will be explained with reference to FIGS. 1 to 6. FIGS. 1 to 3 show the case where it is attached to a header, and FIG. 1 is an enlarged sectional view of the main part of FIG. 2 is an enlarged view taken in the direction of arrow A in FIG. 1, and FIG. 3 is an enlarged view of the main part of FIG. 16 in Figures 2 and 3 is an index pin (position changes depending on the orifice size);
17 is a clamp for fixing the orifice plate 18, 19 is an orifice plate fixing seat, 20 is a welded part, the flow rate adjusting device 9 is provided in the header 8, and the orifice plate 18 is welded 20 to the header 8. It is fixed to a fixed seat 19 using clamping 17.

Next, FIGS. 4 to 6 show the case where a flow rate adjustment device is attached to the evaporation tube. FIG. 4 shows the orifice plate 18 constituting the flow rate adjustment device 9 as a heater tube (evaporation tube).
It is fixed by welding 23 within an orifice mounting pipe 22 which is welded 21 to 10.

Further, in the embodiment shown in FIG.
The orifice 25 constituting the flow rate adjustment device 9 is directly formed in the pipe 24 that has been opened.

Next, to explain the operation, the flow in the pipe is stabilized in the low flow rate region by the flow rate adjusting device 9, and the size of the device 9 is determined so as to exceed the buoyancy in the lowest flow rate region.
By providing the flow rate adjustment device 9 as described above,
More fluid is distributed to tubes that absorb more heat. Note that at this time, the valve 13 is closed and the bypass pipe 12 is not used. Further, the opening and closing of the valve 13 is controlled by the flow rate, that is, the boiler load.

This invention reduces the pressure drop in the low flow area (decreases as the square of the flow rate) in a system that forms downflow heat exchange.
This prevents the buoyancy of the fluid due to heating and the pressure loss of the system from being reversed, causing a backflow phenomenon and damaging the system due to the generation of temperature between the tubes. This phenomenon is due to vapor and vapor/liquid multiphase flow. In order to prevent this, the present invention provides a flow rate adjustment device at the inlet of the heat transfer tube.

However, once resistance is added to the system, when the output of the boiler increases, the flow rate inevitably increases, resulting in an excessive pressure loss. Although the pressure loss itself does not directly harm the system, it increases the power consumption of the feed water pump in the boiler and requires an increase in the design pressure on the upstream side of the system.
It becomes uneconomical. For this reason, an extra-system bypass is provided, and the extra-system bypass adjusts the amount of bypass according to the output of the boiler, something that has never been seen before. In this way, the present invention measures the operation of the system by adding resistance within the system using a flow regulating device (in this case, an orifice is proposed) and a bypass line, and we hope for a synergistic effect. If you don't, it won't work.

Since the present invention is configured as explained in detail above, the flow in the pipe is stable in the boiler low load region,
Can prevent overheating. In addition, the temperature distribution in the direction of the tube array can be made uniform, preventing excessive stress from occurring, and
It reduces excessive pressure loss in a high flow rate region and has excellent effects such as being economical.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a flow rate control device in a heat exchanger showing an embodiment of the present invention, and FIG. 2 is an A of FIG. 1.
Arrow view, Figure 3 is a detailed view of the main parts in Figure 1,
FIG. 4 is a side sectional view of a flow rate regulating device showing an embodiment of the present invention different from FIG. 1, and FIG. 5 is B to B in FIG. 4.
An enlarged sectional view, FIG. 6 is a side sectional view of a flow rate regulating device different from that in FIG. 4, FIG. 7 is a piping diagram of a heat exchanger showing an embodiment of the present invention, and FIG. A front view of the heat exchanger, and FIG. 8B is a side view of the same. Explanation of the main parts of the figure, 7... Inlet connecting pipe, 8... Header (inlet header), 9... Flow rate adjustment device, 10...
Heater tube (heat transfer tube), 11... Outlet header, 12...
Bypass pipe, 13...valve.

Claims (1)

[Scope of utility model registration request] In a heat exchanger of a type in which fluid is distributed from an inlet header disposed at an upper part to a tube wall composed of a plurality of heat exchanger tubes and reaches an outlet header, a flow rate adjustment device is provided at the inlet portion of the heat exchanger tubes, and A heat exchanger for a boiler, characterized in that an inlet and an outlet of the heat exchanger are communicated through a bypass pipe equipped with a valve.