JP2581122B2 - Steam generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention uses various kinds of exhaust gas from boilers, gas turbines, diesel engines, etc. to generate steam. The present invention relates to a steam generator for evaporating CFC-based and other liquids.

<Prior Art> Generally, when steam is generated using exhaust gas having a relatively low temperature, the flow rate of the exhaust gas may be large, and a plate-fin type heat exchanger that is compact and has a large heat transfer area is suitable. FIGS. 3 and 4 show a steam generator utilizing such a plate fin heat exchanger (Japanese Patent Application No. 60-210479).

FIGS. 3 and 4 schematically show the entirety of such a steam generator, wherein a is an apparatus main body provided with a heat exchanger b and a downcomer section c.

The heat exchanger b has a primary side d on the high temperature side and a secondary side d on the evaporation side.
And the downcomer section c is provided with a heat exchanger b.
Are formed integrally with each other so as to communicate a secondary outlet f formed at the upper part and a secondary inlet g formed at the lower part.

A primary-side inlet h, which is an exhaust gas inlet, is provided at an upper portion of the heat exchanger b, and a primary-side outlet i, which is an exhaust gas outlet after heat exchange, is provided at a lower portion. The primary side of the heat exchanger b,
Fins are provided on each of the secondary sides. In the upper part of the downcomer portion c, a secondary side inlet j for supplying a secondary side fluid flowing in the secondary side e of the heat exchanger b, and steam generated by boiling through the secondary side e are supplied. A secondary outlet k, which is a steam outlet for taking out steam, is provided.

Here, m is a level detector for detecting the liquid level of the secondary fluid in the main body a.

In such a configuration, when a high-temperature exhaust gas is introduced into the primary side d of the heat exchanger b from the primary-side inlet h, and a low-temperature secondary-side fluid is supplied into the downcomer portion c from the secondary-side inlet j, 2
The secondary fluid flows from the secondary inlet g to the secondary e, and is guided to the secondary outlet f. At this time, heat exchange is performed between the primary d and the secondary e. Part of the secondary fluid becomes steam,
It flows out through the secondary outlet f and the secondary outlet k.

<Problems to be Solved by the Invention> The conventional steam generator described above has the following problems.

(1) The primary-side portion of the heat exchanger fins enters the secondary-side outlet f and the secondary-side inlet g, and in particular, the outlet where air / water is separated from the gas / water mixed flow. The fluid flow path of f is narrow,
In addition, since the flow of the secondary fluid changes its direction at a right angle, the flow resistance is large, and the separation of steam and water is difficult to be performed sufficiently.

(2) Since the secondary outlet f and the secondary inlet g do not have the secondary part of the fin portion of the heat exchanger and have only the primary part, the primary side and the secondary side are provided. There is no strength advantage peculiar to a plate fin heat exchanger in which pressure resistance is obtained by both fins, and the pressure resistance at the outlet f and the inlet g is low.

(3) Since the counterflow type is adopted, the flow path lengths of the primary side fluid and the secondary side fluid become equal, the degree of freedom in design is small, and the optimum design may not always be obtained.

Among the above problems (1) and (2), a cross flow plate fin heat exchanger in which the flow path of the primary fluid is horizontal and the flow path of the secondary fluid is vertical is used as the heat exchanger. It will be solved (Japanese Patent Application No. 61-283995). However, in the present invention, the flow path of the primary fluid in the heat exchanger is one-pass,
The temperature difference between the primary fluid and the secondary fluid is greatly different between the inlet side and the outlet side of the secondary fluid, and the temperature difference is small at the secondary fluid outlet side and the primary fluid flows out at a high temperature without sufficient heat exchange. And heat loss is large.

<Object of the Invention> The present invention has been devised in view of such problems of the prior art, and has a small flow resistance on the secondary side, a high pressure resistance, and a large degree of freedom in designing the length of the flow path. The purpose is to provide a vessel.

<Means for Solving the Problems> In order to achieve the above object, the generator of the present invention comprises a crossflow plate fin heat exchanger in which the flow path of the secondary fluid is vertical, and an upper end of the heat exchanger. A hollow cylindrical riser portion connected to the heat exchanger, a downcomer disposed substantially parallel to the heat exchanger, and communicating with the riser portion and the upper portion of the downcomer, having an evaporating liquid level therein, and An upper header having a steam outlet at an upper portion, and a lower communication portion communicating the lower portion of the downcomer with the lower portion of the heat exchanger, wherein at least one of both sides of the heat exchanger has a primary header. Is provided, the flow path of the primary fluid of the heat exchanger descends from the upper primary fluid inlet, across the heat exchanger, down the primary header, and again traverses the heat exchanger. Repeatedly, it is a sheep-intestinal flow path leading to the lower fluid outlet at 1 o'clock. It is a sign.

<Embodiment> One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a steam generator according to the present invention, and a partial cross section is shown. FIG. 2 is a partial cross-sectional view taken along the line II-II of FIG. 1 and 2, reference numeral 1 denotes a cross-flow plate fin heat exchanger, in which secondary fins 11 are disposed vertically, and hot water as a secondary fluid flows vertically. I have. The primary fins 10 are disposed laterally so that the primary fluid flows laterally. Further, in this example, the flow path of the primary fluid is divided into three flow paths in the vertical direction. At the upper end of the heat exchanger 1, a duct-shaped riser portion 2 is provided continuously. Numeral 3 denotes a downcomer which is disposed substantially parallel to the heat exchanger 1 so that the secondary fluid flows from top to bottom. Reference numeral 4 denotes an upper header which surrounds the opening at the upper end of the riser portion 2 and the opening at the upper end of the downcomer 3 so as to communicate with each other.

The liquid level 13 of the secondary fluid is located at a substantially intermediate height in the upper header 4 and serves as a boundary between the vapor and the unevaporated liquid. At the top of the upper header 4, a steam outlet 6 is provided. Reference numeral 5 denotes a lower communication part, which is an opening at the lower end of the downcomer 3 and the heat exchanger 1.
Of the secondary side flow path. 9a,
9b is a primary side header provided on both sides of the heat exchanger 1 and communicating with the primary side flow path of the heat exchanger 1. A primary fluid inlet 7 is provided above one of the headers 9a of the primary header 9.
However, a primary fluid outlet 8 is provided below the other header 9b, and partition plates 14 and 14 are provided below the fluid inlet 7 and above the fluid outlet 8 of each header 9, respectively. The next fluid channel is a sheep-intestinal channel. Reference numeral 12 denotes a liquid level gauge, which is connected to a controller (not shown).

Reference numeral 15 denotes a water supply inlet which is mounted above the downcomer opening of the upper header.

The shape of the fins may be any shape, such as corrugated or short, and various fins may be used to improve the heat transmission coefficient, such as inserting a twisted plate on the primary side or matting the surface of the secondary fins. You may take ingenuity. Next, the operation will be described.

A primary fluid such as a high-temperature exhaust gas flows in through a primary fluid inlet 7 provided above a primary header 9 a on a side surface of the heat exchanger 1, and is formed by a primary fin 10 of the heat exchanger 1. It flows in the primary fluid flow path 10a in the horizontal direction, and the other primary header 9b
Flows into. The primary fluid descends in the primary header 9b, flows through the middle fluid flow path 10b immediately below the upper primary fluid flow path 10a in the opposite horizontal direction, and flows again into the primary header 9a. I do. Similarly, the lower primary fluid path 10 descends in the header.
The fluid flows out through the primary fluid outlet 8 below the primary header 9b through c, during which heat exchange with the secondary fluid takes place.
As described above, the flow path of the primary fluid is a sheep-intestinal flow path that flows downward from above, and includes a high-temperature primary fluid and a high-temperature secondary fluid, a medium-temperature primary fluid and a medium-temperature secondary fluid, Since the low-temperature primary fluid and the low-temperature secondary fluid exchange heat with each other, it also has the advantage of a countercurrent heat exchanger. On the other hand, the secondary fluid is heated in the secondary side flow path 11a having the secondary fins 11 of the heat exchanger, and a part of the secondary fluid evaporates. Natural circulation which rises in the secondary side flow path 11a and flows into the upper header 4 through the riser portion 2 occurs. The vapor is separated into liquid and vapor in the upper header 4, the vapor flows out from the vapor outlet 6 to the outside, the liquid descends in the downcomer 3, and the lower communicating portion 5
Through the heat exchanger 1 again. The liquid level 13 in the upper head 4 is detected by the liquid level gauge 12, and the flow rate of the secondary fluid flowing from the water supply inlet 15 is adjusted.

<Modifications> The present invention is not limited to the above-described embodiment, and the following modifications are included in the scope of the claims.

5 and 6 show a first modification. FIG. 6 is a view taken along the line VI-VI in FIG. As shown in FIGS. 5 and 6, in the present example, the entirety is integrally formed in a square shape. FIG. 7 shows a second modification, which is a modification of the one shown in FIG. That is, two evaporators of the first modified example of FIG. 5 are arranged facing each other with the downcomer 3 in common.

FIGS. 8 and 9 show a third modification. FIG. 9 is a view taken in the direction of arrows IX-IX in FIG. In this embodiment, three steam generators of the embodiment shown in FIG. 1 are arranged side by side, and the upper header 4 and the lower communication part 5 are common, and the downcomer 3 is a heat exchanger 1
Is three, but two.

FIG. 10 shows a fourth modification in which the heat exchangers 1 are arranged radially around a common downcomer 3.

It should be noted that the present invention is not limited to the above-described embodiment and modifications, and the primary fluid may have two or more horizontal flow paths.
The secondary header can be variously modified within the scope of the claims, for example, when the horizontal flow path has two stages, only one side may be used.

<Effects of the Invention> With the configuration described above, the steam generator of the present invention has the following effects.

(1) Since a crossflow plate fin heat exchanger is adopted and the primary fluid flow path is a sheep-intestinal flow path, the steam generator (Japanese Patent Application No. 60-210479) described as a conventional example is used. There is no portion corresponding to the secondary outlet f, and the flow of the secondary fluid is smooth and the separation of steam and water is sufficiently performed.

(2) For the same reason as above, the area where the primary fins and the secondary fins are present in the heat exchanger is the same, and the secondary side inlet g of the conventional heat exchanger having only the primary side is present. Since there is no portion corresponding to the secondary side outlet f, the strength advantage of the plate fin heat exchanger can be sufficiently obtained.

(3) The primary fluid flow path length can be freely selected by changing the number of paths in the sheep-intestinal flow path of the primary fluid and the width of the heat exchanger. Since the length ratio of the side flow path can be freely changed, it becomes easy to design an optimal heat exchanger for a given temperature and flow rate condition.

(4) The primary fluid flows along the sheep-intestinal flow path from top to bottom, and the secondary fluid flows in a substantially vertical direction from bottom to top, so that the advantages of the countercurrent heat exchanger are almost enjoyed. The heat loss is smaller than that of a single-stage cross-flow heat exchanger.

(5) Since the riser section is provided immediately above the heat exchanger, the length of the flow path in the gas-water mixed state of the secondary fluid is increased, so that the buoyancy effect of the generated steam is further increased and natural circulation is activated. Therefore, even if the heat load per unit volume of the heat exchanger increases, a phenomenon similar to the vapor lock in the heat exchanger (when this phenomenon occurs, the amount of evaporation rapidly decreases) is less likely to occur. Therefore, the heat exchanger can be made compact.

[Brief description of the drawings]

FIG. 1 is a side view of a steam generator according to the present invention, which is partially sectioned. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a side view of a conventional steam generator, which is partially cross-sectional. FIG. 4 is a perspective view of the steam generator of FIG. 5 and 6 are views showing a first modification of the steam generator of the present invention. FIG. 5 is a front view, and FIG. 6 is a view taken along the line VI-VI of FIG. FIG. 7 is a perspective view of a second modification of the steam generator of the present invention. 8th
FIG. 9 is a drawing showing a third modification of the steam generator of the present invention. FIG. 8 is a front view, and FIG. 9 is a view taken in the direction of arrows IX-IX in FIG. FIG. 10 is a perspective view of a fourth modification of the present invention. 1 ... heat exchanger, 7 ... primary fluid inlet 2 ... riser section, 8 ... primary fluid outlet 3 ... downcomer, 9 ... primary side header 4 ... upper header 5 ... lower communication Part 6: Steam outlet

Claims (1)

(57) [Claims] 1. A cross flow plate fin heat exchanger in which a flow path of a secondary fluid is in a rigid direction, a hollow cylindrical riser portion connected to an upper end of the heat exchanger, and a heat exchanger. A downcomer disposed substantially in parallel, the riser section communicates with the upper portion of the downcomer, the upper header has an evaporating liquid level inside, and has a vapor outlet at the upper portion, and the heat exchange between the downcomer lower portion and the lower header. And a lower communication portion that communicates with the lower part of the heat exchanger. A primary header is provided on at least one of both sides of the heat exchanger, and a flow path of a primary fluid of the heat exchanger is Crossing the inside of the heat exchanger from the upper primary fluid inlet, descending the primary header, traversing again the heat exchanger, repeating this, and a sheep-intestinal flow path leading to the lower primary fluid outlet. A steam generator characterized in that: