JP2511149B2 - Water heater - Google Patents

Description

The present invention relates to improvements in feed water heaters used in turbine power plants and the like, and various steam condensers for general plants.

[Conventional technology]

FIG. 5 is a vertical sectional side view showing an example of a conventional feed water heater,
6 is a transverse sectional view taken along the line VI-VI in FIG. 5, and FIG. 7 is a detailed view of the central portion of FIG.

In these drawings, a heat transfer tube group (2) of two bending flows by a U-bend tube is arranged in a tubular body (1) whose axis is substantially horizontal, and the heat transfer tube group (2) is a tube plate (3). ) And a plurality of tube support plates (4). As shown in FIG. 7, the central portion of the heat transfer tube group (2) has a tube support plate (4) notched, and an inverted bottom plate composed of a top plate (5a) and both side plates (5b) (5b). Groove-shaped air box (5), body (1)
The air extraction passageway (5c) is formed in the inside of the air extraction passageway (5c). This air box (5) has an air extraction duct (7)
Is provided. Further, a steam inlet nozzle (8) is provided on the upper part of the body (1) and a drain outlet nozzle (9) is provided on the lower part thereof. Further, an inlet side water chamber (10) and an outlet side water chamber (11) are provided on one side of the tube sheet (3).

In the feed water heater having such a structure, the feed water W that has entered the feed water inlet side water chamber (10) cools and condenses the steam S outside the pipe while passing through the tubes of the heat transfer tube group (2), The temperature rises and goes out of the water chamber (11) on the water supply outlet side. On the other hand, the steam S on the heating side enters the shell (1) through the steam inlet nozzle (8) and flows from the periphery of the heat transfer tube group (2) toward the center of the tube group as shown in FIG. . And most of the steam S
Is condensed by heat exchange with the feed water W, but the remaining uncondensed vapor and non-condensed gas are introduced into the air extraction passageway (5c) from the bottom side of the air box (5) and from the air extraction duct (7). It is discharged to the outside of the device. On the other hand, the condensed drain D is discharged from the drain outlet nozzle (9) provided in the lower part of the body (1).

[Problems to be Solved by the Invention]

In order to fully exhibit the performance of the feed water heater, it is important to eliminate the retention area in the heat transfer tube group and to perform heat exchange in all tube groups.

By the way, since the temperature difference between the feed water in the heat transfer pipe and the steam outside the pipe is maximum at the feed water inlet and minimum at the feed water outlet, the ability to condense the steam outside the pipe (heat exchange capacity) is also maximum at the feed water inlet, The minimum at the water supply outlet. In the portion of the heat transfer tube group having a high condensation capacity, the volume is reduced and the pressure becomes low due to the condensation, so that a large amount of steam flows in and the pressure loss in the heat transfer tube group increases. Therefore, the pressure loss in the heat transfer tube group differs in the longitudinal direction.

However, since the actual heat transfer tube group communicates in the longitudinal direction through the air box installed in the center of the tube group, if the flow velocity of the air extraction passage in the air box is relatively low, the static pressure in the air extraction passage will be reduced. Becomes almost uniform in the longitudinal direction. Then,
The heat transfer tube group near the feedwater inlet, which originally has a high condensation capacity, balances with a small pressure loss, so the amount of steam inflow decreases, creating a retention area in the tube group, and lowering the heat transfer function Depending on the material of the heat tube, there is a possibility that ammonia attack (corrosion of the tube due to a small amount of ammonia contained in the steam) may occur. That is, when the condensing capacity is fully exerted, a large amount of steam flows into the heat transfer tube group, so the pressure loss of the heat transfer tube group should be large, but the static pressure in the air box is uniform in the longitudinal direction. In this case, since the pressure around the heat transfer tube group is uniform in the longitudinal direction, even a heat transfer tube group side having a large condensation capacity can tolerate as little pressure loss as the U bend side having a small condensation capacity. Therefore, the amount of inflowing steam is reduced and the pressure loss is reduced.

[Means for solving the problem]

In order to solve the above-mentioned conventional problems, the present invention provides a tubular cylinder whose axis is substantially horizontal, a two-fold flow heat transfer tube group by a U-bend tube arranged in the cylinder, and the heat transfer tube group. A plurality of tube support plates to support, a reverse groove type air box arranged along the axis to form an air extraction passage therein, and a throttle ratio sequentially different in the longitudinal direction in the air extraction passage. A water heater provided with a plurality of weirs is proposed.

[Action]

In the present invention, due to the throttling effect of the weir provided in the air box, the static pressure in the air extraction passage is high on the U bend side and low on the tube sheet side. On the other hand, since the static pressure around the heat transfer tube group is uniform over the entire area, the pressure loss in the heat transfer tube group is small on the U bend side and large on the tube sheet side. Therefore, by appropriately selecting the height of the weir (throttle strength), it is possible to generate a static pressure distribution such that the amount of inflow steam matches the distribution of the condensation capacity in the longitudinal direction of the tube group. It is possible to eliminate the retention area of the steam flow in the heat pipe group.

〔Example〕

FIG. 1 is a longitudinal side view showing an embodiment of the present invention, and FIGS. 2 and 3 are II-II chain lines and III of FIG. 1, respectively.
It is a transverse cross-sectional view taken along the line III-III. In these figures, the portions similar to the conventional one described with reference to FIG. 5 to FIG.
The same symbols are attached and detailed explanations are omitted.

In the present embodiment, a plurality of pipe support plate (4) portions below the air extraction passageway (5c) formed by the air box (5) are extended upward, that is, into the air extraction passageway (5c) to form a weir. (6) is formed. The amount of extension, that is, the height of the weir (6) is higher on the U bend side of the heat transfer tube group (2),
The tube plate (3) side is gradually lowered. Therefore, the drawing ratio of the weir (6) gradually decreases from the U-bend side toward the tube sheet side.

As described above, in the present embodiment, a plurality of weirs (6) having different drawing ratios in the longitudinal direction are formed on the tube support plate (4) in the air box (5), and the tube plate (from the U bend side is formed). 3) By narrowing the flow of extracted air flowing to the side (to the side with high condensation capacity), a static pressure distribution corresponding to the condensation capacity in the longitudinal direction of the heat transfer tube group is generated, and a retention area is created in the steam flow in the heat transfer tube group. Without it, all heat transfer tube groups can work effectively. FIG. 4 is an explanatory diagram showing the longitudinal distribution of the pressure around the heat transfer tube group and the pressure in the air box, comparing the conventional case and the case of the present embodiment.

In order to fully exhibit the performance of the feed water heater, it is necessary to generate a static pressure distribution in the air box at the center of the tube group in proportion to the condensation capacity in the longitudinal direction of the tube group.
The purpose cannot be achieved only by making the bend side high pressure and the tube sheet side low pressure. The flow in the air box has a larger flow rate toward the downstream side (tube plate side) due to the inflow of extracted air from the heat transfer tube group.Therefore, it is necessary to gradually enlarge the extraction air passage so that it does not become too narrow. is there.

〔The invention's effect〕

According to the present invention, since it is possible to prevent a stagnation region from occurring in the heat transfer tube group under the air box on the tube plate side, which originally has a high condensing capacity, the entire heat transfer tube group works effectively, and heat transfer can be performed as compared with the conventional case. Performance is improved.

Further, when a retention area occurs in the heat transfer tube group in the conventional feed water heater, there is a possibility that ammonia attack may occur depending on the material of the heat transfer tube, but the present invention exerts a sufficient effect also in preventing the occurrence of ammonia attack. it can.

[Brief description of drawings]

FIG. 1 is a longitudinal side view showing an embodiment of the present invention, and FIGS. 2 and 3 are II-II chain lines and III-I of FIG. 1, respectively.
It is a cross-sectional view taken along the II chain line. FIG. 4 is an explanatory diagram showing the longitudinal distribution of the pressure around the heat transfer tube group and the pressure in the air box in comparison with the conventional case and the case of the present embodiment. Fifth
FIG. 6 is a vertical sectional side view showing an example of a conventional feed water heater, FIG. 6 is a horizontal sectional view taken along line VI-VI of FIG. 5, and FIG. 7 is a detailed view of a central portion of FIG. (1) …… Body, (2) …… Heat transfer tube group, (3) …… Tube plate, (4) …… Tube support plate, (5) …… Air box, (5a) …… Top plate, ( 5b) ... side plate, (5c) ... air extraction passage, (6) ... weir, (7) ... air extraction duct, (8) ... steam inlet nozzle, (9) ... drain outlet nozzle , (10) …… Inlet side water chamber, (11) …… Outlet side water chamber, W …… Water supply, S …… Steam, D …… Drain.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshio Shimada, 2-1-1 Nihama, Arai-cho, Takasago-shi, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Plant (72) Naoki Hasegawa 2-1-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture No. 1 Mitsubishi Heavy Industries, Ltd. Takasago Plant (56) Reference JP-A-58-86302 (JP, A)

Claims (1)

(57) [Claims] 1. A tubular cylinder whose axis is substantially horizontal, and a two-fold flow heat transfer tube group formed by a U-bend tube arranged in the cylinder.
A plurality of tube support plates that support the heat transfer tube group, a reverse groove type air box that is arranged along the axis to form an air extraction passage therein, and a draw ratio along the longitudinal direction in the air extraction passage. A plurality of weirs are arranged so that the water supply heaters are sequentially different from each other.