JPS62703A - Evaporator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an evaporation device, and in particular is used as an evaporation device such as a fluidized bed boiler or a shell-and-tube heat exchanger that is expected to have high performance. It is something.

2. Description of the Related Art High-performance heat transfer tubes for internal boiling in a fluidized bed boiler, which is a conventional evaporator, include rifled tubes having a spiral groove on the inner surface of the tube and tubes having a torsion slope inserted therein.

, Problems to be Solved by the Invention The heat transfer tubes passing through the fluidized bed of the fluidized bed boiler (intrabed heat transfer tubes) and the furnace ceiling furnace wall tubes (ceiling heat transfer tubes) have shallow inclination angles close to horizontal. It is made up of. For this reason, as shown in FIGS. 8 and 9, for example, when the liquid to be evaporated flows in the heat transfer tube 21 as shown by the arrow 22, the evaporated gas phase coalesces and concentrates in the upper part of the tube flow path. , a cooling limit occurs on the upper wall side of the heat exchanger tube 21 due to the generation of slag bubbles 23 and complete covering of the inner wall surface of the tube with a gas phase. The heat transfer tubes 21 are designed under heat flux conditions that are below this cooling limit.Increasing this heat flux not only reduces the overall heat transfer area, but also eliminates other structural layout constraints. can also be alleviated. Note that FIG. 8 shows a case where the heating heat flux is large, and FIG. 9 shows a case where it is small.

The conventional rifle tube described above has high heat transfer performance due to the increased heat transfer area due to the spiral grooves, but the swirling effect of the flow due to the spiral grooves is small, and slag bubbles coalesce and concentrate in the upper cross section of the tube. The effect on flow is small. Therefore, there is a problem in that it is not possible to significantly change the heat flux conditions where the cooling limit occurs due to the growth and increase of slag bubbles. In addition, the above-mentioned pipe with the twisted slope inserted has high heat transfer performance by giving a small swirling effect to the flow inside the pipe, but since the flow resistance increases significantly, the circulation flow characteristics
There is a problem that the performance as an evaporator is deteriorated.

The present invention attempts to solve the above problems. That is, an object of the present invention is to provide a high-performance evaporator that can improve the cooling limit heat flux value of the upper part of the heat transfer tube body and suppress the increase in flow loss accompanying the improvement. The purpose is to

Means to solve problems The flow path of the heat transfer tube of the evaporator was divided into upper and lower sections.

In other words, in the configuration of the present invention, the internal flow path of the heat transfer tube body, which is oriented horizontally within the range of an inclination angle from horizontal to nearly horizontal, and in which the internal liquid boils due to an external source, has an upper flow path and a lower flow path. It is characterized by being divided into two roads.

The heat flux of an external heat source passing through a horizontal or nearly horizontal heat exchanger tube is not uniform in the circumferential direction.Especially in the case of a fluidized bed type, the lower wall side of the heat exchanger tube, which is the upstream side of the air, is higher. , the upper wall side is low. For this reason, the number of steam bubbles generated inside the heat transfer tube body is large on the lower wall side and small on the upper wall side. Therefore, if the internal flow path of the heat transfer tube body is not divided into upper and lower parts, the 5 steam bubbles will coalesce and concentrate in the upper part due to the gravitational effect, producing large slag bubbles.

However, in the present invention, the internal flow path of the heat transfer tube that is oriented sideways is divided into an upper flow path and a lower flow path by a partition plate, etc., so that the flow rate flowing into the heat transfer tube is increased. Steam bubbles distributed to the downstream channel and generated in the lower channel are prevented from flowing into the upper channel and do not coalesce with the vapor bubbles in the upper channel.

The size of slag bubbles in the upper flow path can be reduced, and the cooling limit heat flux value of the upper part of the heat transfer tube body can be improved.

Embodiment FIGS. 1 to 4 show a fluidized bed boiler as a first embodiment of the present invention, FIG. 5 similarly shows a second embodiment, and FIG.
The figure also shows the third embodiment, and FIG. 7 similarly shows the fourth embodiment.

In Fig. 1, l is a heat exchanger tube installed horizontally or at a near-horizontal inclination angle, and a partition plate 2 is inserted inside, so that the internal flow path of the heat exchanger tube is divided into an upper flow path 3 and a lower flow path. It is divided into a flow path 4. One end of the heat transfer tube body 1 communicates with the ladder 6 via one vertical tube 5 to the lower part, and the other end communicates with the drum 8 via the other vertical tube 7.

An arrow indicating the blowing of air, lO is a fluidized bed, 1
1 is an arrow indicating combustion gas. Note that the partition plate 2 is inserted only into the heat transfer tube body 1, and is not inserted into the non-heating part (not shown) at the inlet/outlet part or the vertical pipes 5 and 7.

In the fluidized bed boiler as an evaporator configured as shown in FIG. Similarly, since the heat transfer tube body 1 is divided into an upper passage 3 and a lower passage 4 by a partition plate 2, as shown in FIGS.
The steam bubbles generated in the upper flow path 3 are prevented from flowing into the upper flow path 3 by the partition plate 2, and only the steam bubbles generated in the upper flow path 3 are present in the upper flow path 3. Therefore, the lower flow path 4
Even if slag bubbles 12 are formed in the slag bubbles 12, these bubbles 12 do not flow into the upper channel 3, and the slag bubbles 13 in the upper channel 3 are replaced by the slag bubbles 23 explained in FIGS. 8 and 9.
It will be significantly smaller than that.

Moreover, the flow rate flowing into the heat transfer tube body 1 from one vertical tube 5 is as follows:
Since it is distributed into the upper flow path 3 and the lower flow path 4, the partition plate 2
The ratio of the cross-sectional area of the upstream and downstream passages due to the difference in the installation position of the heat exchanger tube 1 differs between the heat flux Q2 on the earth wall side and the heat flux Q on the lower wall side (Q+ > Q2 in Fig. 4). In consideration of,
The ratio of the flow rate U2 of the fluid distributed to the upper flow path 3 and the flow rate U1 of the fluid distributed to the lower flow path 4 (in FIG. 3, U+ < U2
) t-can be selected and designed.

The embodiment shown in Fig. 5 differs from the case in Fig. 2 in that the partition plate 2 is a bent plate, and the companion embodiment shown in Fig. 6 has the support plate 14: all added. The only difference from the case shown in FIG. 2 is that the other points are the same.

In the embodiment shown in FIG. 7, the heat exchanger tube body 1 is made of a parallel front type in which two heat exchanger tubes 15 and 16 are made close to each other or joined together, and connecting plates 17 with good heat conductivity are provided on both sides.
and 18 are provided. That is, the upper heat exchanger tube 15 constitutes the upper flow path 3, and the lower heat exchanger tube 16 constitutes the lower flow path 4. This embodiment of FIG. 7 has the advantage of increased heat transfer area.

In each of the above embodiments, the case where the evaporator is a fluidized bed boiler is described, but a shell-and-tube type boiler is used in which the liquid inside the heat exchanger tube body, which is horizontal or has an inclination angle close to horizontal, is boiled by an external heat source. Also suitable for evaporation devices such as heat exchangers.

It can be implemented in a similar manner.

Effects of the Invention In the evaporation device of the present invention, the internal flow path of the heat transfer tube body, which is oriented horizontally within the range of an inclination angle from horizontal to near-horizontal, and in which the internal liquid is boiled by an external heat source, has an upper flow path and a lower flow path. Since the steam bubbles generated in the lower flow path are divided into the upper flow path and the upper flow path, steam bubbles generated in the lower flow path are prevented from flowing into the upper flow path and do not combine with the steam bubbles in the upper flow path. , the size of slag bubbles in the passage can be reduced, and the flow rate flowing into the heat transfer tube is distributed to the upstream and downstream passages, so the ratio of the passage cross-sectional area of the upper passage and the lower passage can be adjusted appropriately. By selecting and optimizing their flow velocity ratio, the size of the slag bubbles in the upper channel can be made so small.
The cooling limit heat flux value of the upper part of the heat transfer tube body can be improved, and the increase in flow loss can be reduced by 1 by changing the hydraulic diameter alone.
, extremely small.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing the first embodiment of the present invention;
The figure is an enlarged perspective view of the heat exchanger tube shown in Figure 1 and partially shown in cross section, Figure 3 is a cross sectional side view showing the action of the heat exchanger tube, and Figure 4 is a cross sectional front view of Figure 3. , FIG. 5 is a perspective view of the second embodiment of the present invention corresponding to FIG. 2, FIG. 6 is a perspective view of the third embodiment, and FIG. 7 is a perspective view of the fourth embodiment. , FIG. 8 is an explanatory diagram of the function of a conventional heat exchanger tube, and FIG. 9 is an explanatory diagram of another function. DESCRIPTION OF SYMBOLS 1... Heat exchanger tube body, 2... Partition plate, 3... Upper channel, 4... Lower channel, 5... Vertical pipe, 6... Lower header, 7... Vertical tube, 8...Drum, 9...Arrow indicating air flow, 10...Fluidized bed, 11...
Arrows showing the flow of combustion gases. Figure 4

Claims (1)

[Claims] 1. The internal flow path of the heat transfer tube, which is oriented horizontally within a horizontal to near-horizontal inclination angle range and in which the internal liquid boils due to an external heat source, is divided into an upper flow path and a lower flow path. An evaporation device characterized by: