Heat exchanger

Abstract

A heat exchanger is provided in which steam locking is prevent and which allows steam condensate generated in heat transfer tubes to quickly flow down into a condensate outlet chamber. The heat exchanger includes a shell (1) in which a plurality of heat transfer tubes (5) are disposed. The shell (1) has an inlet (2) for fluid to be heated through which fluid to be heated flows in and an outlet (3) for heated fluid through which heated fluid flows out. The heat transfer tubes (5) are penetratingly fixed, at their ends, to a tube plate (7). The tube plate (7) has an end face covered by partition chamber cases (8) and (9) provided with a top steam inlet (10) through which steam flows in and a bottom condensate outlet (11) through which condensate flows out. The tube plate (7) and the partition chamber cases (8) and (9) form, between them, a partition chamber having a partition plate (14) partitioning the partition chamber into a steam inlet chamber (12) having the steam inlet (10) and a condensate outlet chamber (13) having the condensate outlet (11). The partition plate (14) has an opening (15) through which the steam inlet chamber (12) and the condensate outlet chamber (13) are communicated with each other, and a steam trap (16) for draining steam condensate from the steam inlet chamber (12) into the condensate outlet chamber (13) is connected to the opening (15) of the partition plate (14).

Description

FIELD OF THE INVENTION

The present invention relates to a heat exchanger for exchanging heat between steam flowing as a heating fluid through plural heat transfer tubes installed in the shell of the heat exchanger and a fluid to be heated flowing outside the heat transfer tubes in the shell.

BACKGROUND OF THE INVENTION

A known heat exchanger is described in JP-A No. H05-34084. The heat exchanger has a shell which is provided with an inlet for fluid to be heated and an outlet for heated fluid and which includes plural heat transfer tubes installed therein. In the shell, the heat transfer tubes are, at their ends, penetratingly fixed to a tube plate. The tube plate has an outer face covered by a partition chamber case having, in an upper part thereof, a steam inlet through which steam flows in and, in a lower part thereof, a condensate outlet through which condensate flows out. Thus, a partition chamber is formed between the tube plate and the partition chamber case. The partition chamber is partitioned by a partition plate into a steam inlet chamber having the steam inlet and a condensate outlet chamber having the condensate outlet. Though not described in JP-A No. H05-34084, the partition plate has a weep hole to allow steam condensate to flow down from the steam inlet chamber into the condensate outlet chamber.

SUMMARY OF THE INVENTION

The known heat exchanger described above has a problem that, when the amount of steam condensate in the steam inlet chamber is small, steam leaks into the condensate outlet chamber via the weep hole thereby causing steam locking to prevent the steam condensate generated in the heat transfer tubes from flowing down into the condensate outlet chamber.

It is an object of the present invention to provide a heat exchanger which can prevent steam locking and allow condensate generated in heat transfer tubes to flow down quickly into a condensate outlet chamber.

To achieve the above object, the present invention provides a heat exchanger including a shell in which a plurality of heat transfer tubes are disposed. The shell has an inlet for fluid to be heated through which fluid to be heated flows in and an outlet for heated fluid through which heated fluid flows out. The heat transfer tubes are penetratingly fixed at their ends to a tube plate. The tube plate has an end face covered by a partition chamber case provided, in an upper part thereof, with a steam inlet through which steam flows in and, in a lower part thereof, with a condensate outlet through which condensate flows out. The tube plate and the partition chamber case form, between them, a partition chamber having a partition plate partitioning the partition chamber into a steam inlet chamber having the steam inlet and a condensate outlet chamber having the condensate outlet. The partition plate has an opening through which the steam inlet chamber and the condensate outlet chamber are communicated with each other, and a steam trap for draining steam condensate from the steam inlet chamber into the condensate outlet chamber is connected to the opening of the partition plate.

According to the present invention, a partition plate is provided with an opening through which a steam inlet chamber and a condensate outlet chamber are communication with each other, and a steam trap for draining steam condensate from the steam inlet chamber into the condensate outlet chamber is connected to the opening of the partition plate, so that, when steam condensate flows from the steam inlet chamber into the steam trap, the steam trap opens its valve to allow the steam condensate to be discharged into the condensate outlet chamber and so that, when steam flows from the steam inlet chamber into the steam trap, the steam trap closes its valve to prevent the steam from leaking out into the condensate outlet chamber. Thus, steam locking is prevented, and the steam condensate generated in heat transfer tubes is allowed to quickly flow down into the condensate outlet chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a kettle-type reboiler representing an embodiment of a heat exchanger according to the present invention.

FIG. 2 is a section view of the steam trap shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. An approximately cylindrical shell 1 is provided: in a lower right part thereof as seen in FIG. 1, with an inlet 2 for fluid to be heated through which fluid to be heated flows in; in an upper middle part thereof as seen in FIG. 1, with an outlet 3 for heated/vaporized fluid through which heated/vaporized fluid flows out; and, in a lower left part thereof as seen in FIG. 1, with a blow port 4 through which heated/nonvaporized fluid flows out. Plural heat transfer tubes 5 are installed in the shell 1 to extend along the longitudinal direction of the shell 1. The heat transfer tubes 5 are U-shaped, being curved in front of a weir 6. The ends opposite to the curved portion of the heat transfer tubes 5 are penetratingly fixed to a circular tube plate 7. The outer face of the tube plate 7 is covered by partition chamber cases 8 and 9. The partition chamber case 8 is provided, in an upper middle part thereof as seen in FIG. 1, with a steam inlet 10 through which steam flows in and, in a lower middle part thereof as seen in FIG. 1, with a condensate outlet 11 through which condensate flows out. The tube plate 7 and the partition chamber cases 8 and 9 thus form a partition chamber which is divided by a flat partition plate 14 into a steam inlet chamber 12 having the steam inlet 10 and a condensate outlet chamber 13 having the condensate outlet 11.

The partition plate 14 has an opening 15 through which the steam inlet chamber 12 and the condensate outlet chamber 13 are communicated with each other. A steam trap 16 for draining steam condensate from the steam inlet chamber 12 into the condensate outlet chamber 13 is fixedly welded to the partition plate 14 such that the steam trap 16 is connected to the opening 15. Reference numeral 17 in FIG. 1 represents plural baffle plates partitioning the interior of the shell 1, across the longitudinal direction of the shell 1, so as to regulate the flow of fluid to be heated. Steam coming in the steam inlet chamber 12 through the steam inlet 10 is distributed to the heat transfer tubes 5 via the tube plate 7 and, while flowing through the heat transfer tubes 5, exchanges heat with the fluid to be heated flowing, after coming in the shell 1 through the inlet 2 for fluid to be heated, outside the heat transfer tubes 5. The steam condensate generated, as a result of heat exchange, in the heat transfer tubes 5 flows down into the condensate outlet chamber 13 to then flow out through the condensate outlet 11. The fluid heated through heat exchange and vaporized outside the heat transfer tubes 5 in the shell 1 flows out through the outlet 3 for heated/vaporized fluid. The fluid heated through heat exchange without being vaporized outside the heat transfer tubes 5 in the shell 1 flows over the weir 6 and then flows out through the blow port 4. The steam condensate is drained from the steam inlet chamber 12 via the steam trap 16 into the condensate outlet chamber 13 to then flow out through the condensate outlet 11.

Even though the steam trap 16 connected to the opening 15 of the partition plate 14 is a free-float steam trap as shown in FIG. 2, the present invention allows it to be of any other type, for example, a lever float type, bucket type, bimetal type, expansion/contraction type, or disc type. Referring to FIG. 2, the free float steam trap 16 has a casing including a body 21 and a cover 22 bolted to the body 21. A valve chamber 23 is formed in the casing. The body 21 has, in an upper part thereof, an inlet 24 and, in a lower part thereof, an outlet passage 25 and an outlet 26. The inlet 24 is communicated with an upper part of the valve chamber 23. The inlet 24 is also communicated with the opening 15 of the partition plate 14. A valve seat 29 having a valve orifice 27 is screwed to a portion, making up a lower side wall of the valve chamber 23, of the cover 22. The valve orifice 27 faces diagonally downward. The cover 22 has an outlet passage 30. A lower part of the valve chamber 23 is communicated with the outlet 26 via the valve orifice 27 and the outlet passages 30 and 25.

In the valve chamber 23, a hollow spherical float 31 for opening and closing the valve orifice 27 is disposed in a free state. A fork-shaped float seat 32 against which the float 31 abuts when positioned to close the valve orifice 27 is disposed below the float 31. A bimetal 33 is disposed as a temperature-responsive member in the valve chamber 23. The bimetal 33 has an approximately U-shaped section and is fixed, at an end thereof, to the cover 22 with a screw 34. When subjected to a high temperature, the bimetal 33 is deformed to squeeze its sectional U-shape, so that it does not interfere with the float 31. When subjected to a low temperature, the bimetal 33 is deformed to widen its sectional U-shape, so that it pushes the float 31 rightward, as seen in FIG. 2, to open the valve orifice 27. A cap-shaped filter 35 for capturing foreign matter is fixed to the body 21 with a screw 36 such that the filter 35 is positioned upstream of the float 31 in the valve chamber 23.

In the steam trap 16, when the temperature in the valve chamber 23 is low, the bimetal 33 is deformed to widen its sectional U-shape, thereby pushing the float 31 away and opening the valve orifice 27. This causes the low-temperature air and condensate flowing into the valve chamber 23 to be discharged through the valve orifice 27 and the outlet 26 into the condensate outlet chamber 13. When the low-temperature air and condensate is discharged from the valve chamber 23 and the temperature of condensate flowing into the valve chamber 23 rises, the bimetal 33 is deformed to squeeze its sectional U-shape not to interfere with the float 31. When condensate flows into the valve chamber 23 causing the float 31 to be floated up and the valve orifice 27 to be opened, the condensate is discharged through the valve orifice 27 and the outlet 26 into the condensate outlet chamber 13. When steam flows into the valve chamber 23 causing the float 31 to descend and the valve orifice 27 to be closed, the steam is prevented from leaking out. In this way, steam locking is prevented, and the condensate generated in the heat transfer tubes 5 is allowed to quickly flow down into the condensate outlet chamber 13.

The heat exchanger according to the present invention can be applied to, for example, kettle-type reboilers, feed-water heaters, evaporators, and air-conditioners.

Claims

1. A heat exchanger including a shell in which a plurality of heat transfer tubes are disposed, the shell having an inlet for fluid to be heated through which fluid to be heated flows in and an outlet for heated fluid through which heated fluid flows out, the heat transfer tubes being penetratingly fixed at their ends to a tube plate, the tube plate having an end face covered by a partition chamber case provided, in an upper part thereof, with a steam inlet through which steam flows in and, in a lower part thereof, with a condensate outlet through which condensate flows out, the tube plate and the partition chamber case forming, between them, a partition chamber having a partition plate partitioning the partition chamber into a steam inlet chamber having the steam inlet and a condensate outlet chamber having the condensate outlet, wherein the partition plate has an opening through which the steam inlet chamber and the condensate outlet chamber are communicated with each other and wherein a steam trap for draining steam condensate from the steam inlet chamber into the condensate outlet chamber is connected to the opening of the partition plate.