JPH09217993A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate type heat exchanger in which a pressure loss is decreased and a clogging is rarely generated. SOLUTION: A heat exchanging plate 10 of this plate type heat exchanger is provided with a heat transfer surface 14 on a substantially circular plate and fluid flow openings 15a and 15b opened for first fluid which heat exchange with each other and fluid flow openings 16a and 16b opened for second fluid which heat exchange with each other, with the heat transfer surface 14 provided therebetween. These openings are respectively opened in the vicinities of the peripheral edge part 11 of the plate. Thus, the fluid directed toward the peripheral edge part of the plate from the openings is guided circumferentially along the circular arc shaped peripheral edge part 11 of the plate. Accordingly, the retention phenomenon of the fluid is not generated, nor pressure loss or foreign materials appear on the heat transfer surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in plate heat exchangers.

[0002]

2. Description of the Related Art A plate heat exchanger has an advantage that it has a large heat transmission rate and can be made compact. In particular, the heat exchange plate 60 as shown in FIG.
In the plate heat exchanger of the type in which air- and liquid-tight contact is performed via 61a, and tightening bolts are bridged between the front frame plate and the end frame plate to tighten and fix, the capacity can be increased or decreased. Since the surface of the heat exchange plate 60 can be completely cleaned, a solution in which crystals are easily deposited on the surface of the plate, a fluid that must maintain a sterile state or a clean state, or a high-purity fluid, etc. Suitable for handling. 69
Is a notch through which the guide bar is inserted, and the gasket 61
a is a pair of openings 62 and 63 on one side and a pair 6 of openings on the other side.
This is a gasket for partitioning between 4, 65.

On the other hand, in the plate heat exchanger, the gap between the heat transfer surfaces through which the fluid passes is narrow, so that the pressure loss per unit flow is significantly larger than that of other types of heat exchangers. However, it is difficult to increase the size, and the heat resistance of the type using the above-mentioned gasket has drawbacks such as a limited operating temperature and a low operating pressure. In order to eliminate such a defect, instead of housing the heat exchange plate in a shell or sealing with a gasket, the heat exchange plates that are in contact with each other are brazed at the contact point. It is known that these are integrated. In particular, the latter type that is integrated by brazing has excellent pressure resistance, but unlike the gasket type, disassembly and cleaning is not possible, and it is difficult to remove the adhesion and deposition of substances on the heat transfer surface. However, depending on its use, it may become a fatal defect.

The present inventor has, for example, a conventional heat transfer surface having a herringbone projection 68 press-molded when trial and error are repeated in order to eliminate the drawbacks of these plate heat exchangers. For the purpose of enlarging the heat transfer surface without changing the length of the heat transfer surface from the opening 62 on one side to the opening 63 on the other side in the heat exchange plate 60 of
In the shape of the heat exchange plate 60 in FIG. 6, an attempt was made to expand a rectangle long in the vertical direction in the horizontal direction (in other words, to approximate a square).

Now, assuming that one fluid to be heat-exchanged flows from the opening 62 located at the bottom to the opening 63 located at the top, the shape of the heat-exchange plate 60 becomes closer to a square. The slope of the flow path 67 toward the side edge 66 farther from the opening 62 becomes closer to horizontal and becomes gentler, and the side edge 66 has an increased force for stopping the flow from the opening 62 to the side edge. Therefore, in the flow from the opening 62 to the side edge 66, the pressure loss becomes larger than that in the flow in the other directions, and the stagnation phenomenon of the flow occurs, and the components in the heat exchange fluid are deposited and adhered. Or
There has been a dilemma in which solid matters in the heat exchange fluid deposit and the clogging phenomenon easily occurs. In particular, it was found that the deposition of foreign matter and the phenomenon of precipitation were remarkable at the periphery of the opening serving as a fluid inlet / outlet, and were the largest cause of clogging (pressure loss), and the present invention was completed. .

[0006]

A first object of the present invention is to disclose a plate heat exchanger that has a small pressure loss and is relatively easy to be upsized. A second object of the present invention is to disclose a plate heat exchanger in which a substance does not adhere to or deposit on a heat transfer surface.

[0007]

A first aspect of the present invention is to provide a plurality of heat exchange plates in a gas-liquid tight contact with each other in a gas-tight manner so as to exchange heat between the heat exchange plates. In the plate heat exchanger in which the flow paths are alternately provided in a state of being adjacent to each other, the heat exchange plate is provided with a heat transfer surface on a substantially circular flat plate, and the heat transfer surface is sandwiched between the heat transfer plates. It comprises a pair of fluid passage openings for one fluid and a pair of fluid passage openings for the second fluid, each of the two pairs of passage openings opening near the periphery of the flat plate. By doing so, the fluid flowing from the opening toward the peripheral edge of the flat plate is configured to be guided in the circumferential direction along the peripheral edge of the flat plate having an arc, and the plate heat exchanger is characterized in that.

In the plate heat exchanger according to the first aspect, the heat transfer surface may simply be a flat plate, or an uneven surface provided for expanding the heat transfer area, for example, a herringbone. It may be an uneven surface composed of protrusions or corrugated protrusions. When flowing out from the fluid passage opening to the heat exchange passage formed between the heat transfer surfaces, there is substantially no side edge that collides with the flow in the outflow direction and kills the flow force, and one opening Even if the outflow direction is in the direction opposite to the other opening,
Since the fluid is smoothly guided along the arc-shaped peripheral edge, the flow does not stagnant, the pressure loss is small, and the deposition of foreign matter on the heat transfer surface, which is apt to occur in the past, is prevented.

According to a second aspect of the present invention, in the heat exchanger defined in the first aspect, the fluid passage opening has a substantially elliptical shape extending along the peripheral edge of the flat plate forming an arc, The plate heat exchanger is characterized in that the heavy contact portions of the heat exchange plates adjacent to each other are integrally joined by brazing.

In the plate heat exchanger according to the second aspect, when contacting with each other in a gas- and liquid-tight manner, one of the two fluid passage openings is separated from the other in a gas- and liquid-tight manner. Gasket (for the gasket 6 in FIG. 6
1a) is not necessary and the openings can be isolated from each other in a very small range, so that the factors that obstruct the flow force flowing along the arcuate peripheral portion are further reduced. Further, the fluid passage opening having a substantially elliptical shape can maintain a sufficient opening area without changing the opening area, and a sufficient distance can be secured between the opening and the arcuate peripheral edge portion. This has the effect of promoting the fluid guiding effect of the part. Therefore, it is highly effective in preventing dirt and clogging of the heat exchanger due to foreign matter, and by integrally combining the heat exchange plates, the disadvantages of disassembly and cleaning cannot be greatly mitigated, and applications requiring high purity, The applications can be expanded to applications in which breeding of miscellaneous bacteria is disliked or applications to high-pressure fluids.

[0011]

1 and 2 show one embodiment of the plate heat exchanger of the present invention, and FIG.
FIG. 6 is a partially omitted cross-sectional explanatory view as seen from the direction of the -A cross section. The plate heat exchanger 1 is configured by contacting the heat exchange plates 10 as shown in FIG. 2 and integrally connecting the contact portions by brazing. Brazing is appropriately performed according to the metal material of the heat exchange plate, such as a method of heating the heat exchange plate 10 itself by a brazing sheet and heating it in a furnace, or a method of heating it in a vacuum furnace with a brazing filler metal in sheet form. Applied.

The heat exchange plate 10 is made of a substantially circular metal plate, and a rising edge 12 is formed on a peripheral edge portion 11 of the heat exchange plate 10 so as to rise while slightly increasing the diameter. The edge of the rising edge 12 is bent in a diametrical direction (a direction substantially perpendicular to the rising direction of the rising edge) so as to be outside the substantially circumferential shape of the rising edge 12 by a constant width. A flange portion 12a extending in one direction is formed. In FIG. 2, the heat transfer surface 1 is formed by press-molding the herringbone protrusions 13 that are bent in a chevron shape, leaving some flat parts above and below the round metal plate.
4.

The heat transfer surface 14 is sandwiched between the flat portions,
A pair of first fluid passage openings 15a and 15b and a pair of second fluid passage openings 16a and 16b are provided at a slight distance from the peripheral portion 11. These passage openings 15a, b, 16a, b are the openings 15a and 15b and the openings 16a and 1 with respect to the horizontal virtual line segment of the two virtual line segments orthogonal to each other at the center of the heat exchange plate.
6b are line-symmetrical with each other, and the openings 15a and 16a and the openings 15b and 16b are respectively line-symmetrical with respect to a vertical virtual line segment. Each of the openings has a substantially elliptical shape extending along the direction in which the arc formed by the rising edge 12 (or the peripheral edge portion 11) extends, and a space through which a fluid flows is formed between the opening and the rising edge 12. It is kept.

The heat exchange plate 1 having such a structure
0 is made to contact each other so that the bending directions of the herringbone protrusions are opposite to each other, and the joining parts are integrally joined by brazing, so that the heat exchange passage of the first fluid and the second fluid are provided between the heat exchange plates. And the heat exchange flow paths are alternately formed. The opening peripheral edges 16c and 16d of the openings 16a and 16b are as shown in FIG.
Another heat exchange plate 10a in which the front side (front side of the paper surface) of the opening periphery overlaps the heat exchange plate 10 from above in FIG.
(See FIG. 3) is integrally joined to the peripheral edge of the opening. Similarly,
The peripheral edges of the openings 15a and 15b are integrally joined to the peripheral edges of the other heat exchange plates that come into contact with each other from the back side of the paper surface.

The front frame plate 2 and the end frame plate 3 are attached to the front side and the rear side of the heat exchange plate which is integrally contacted as described above, and the heat exchange fluid inlet / outlet port is provided in any frame plate. Then, the heat exchanger is completed. In FIG. 2, if the passage opening on the inlet side of the first fluid is 15a, the fluid entering from the first fluid inlet opening in the end frame plate 3 in FIG. Of the first fluid, which is provided in any of the frame plates so as to be divided into the heat exchange passages, flow between the heat transfer surfaces, merge at the outlet opening 15b, and communicate with the passage opening 15b. From outside (not shown) go out of the heat exchanger.

When the first fluid and the second fluid flow countercurrently, the passage opening 16b serves as an inlet passage for the second fluid, and the second fluid inlet is provided in the front frame plate facing the inlet passage. 6 is provided, and the lower passage opening 16a serves as an outlet passage. The first and second fluids flow adjacent to each other via the heat transfer surface of the heat exchange plate to exchange heat. At this time, the fluid that has entered the heat exchanger 1 flows into the heat exchange passage from the branch passage formed by the passage opening 15a (or 16b). At this time, the flow from the passage opening 15a (or 16b) flows out radially in all directions from the opening.

In particular, the flow in the direction opposite to the outlet opening (15b) is also guided by the rising edge 12 provided on the arcuate peripheral portion 11, so that it does not stay. FIG.
In the above, since the left half of the heat transfer surface 14 is farther from the outlet opening than the right half, it is more susceptible to pressure loss, but the opening 16a
Since the passage area 18 of the first fluid that extends in an arc shape is secured between and the rising edge 12 that faces the opening, the flow in this direction is made easier to flow and stays. There is no. Therefore, the heat exchange rate is improved, and the deposition and deposition of foreign substances can be prevented, and the heat transfer surface can be prevented from being stained or clogged. Although the above has exclusively described the function and effect of the present invention with respect to the outlet opening, it goes without saying that the effect of the heat exchange plate having the arcuate peripheral portion is similarly exhibited in the inlet opening. That is, the fluid that has passed through the heat transfer surface is guided to the inlet opening by the arc-shaped peripheral edge portion, flows into the opening peripheral edge from all directions, and does not stay in the flowing direction.

[0018]

[Experimental Example] The present inventor conducted the following experiment in order to compare the performances of the heat exchange plate having the circular contour and the rectangular heat exchange plate. Test pieces S and R formed by forming a heat exchange channel having a heat transfer surface composed of herringbone protrusions inside an aluminum flat plate were cast by the lost foam method, and the contour of the heat exchange channel of one test piece S was The square shape (square shape) was used, and the contour of the heat exchange flow path of the other test piece R was made into a circular shape (round shape), and a pair of circular fluid passage openings 21 and 22 having the same diameter were respectively formed to serve as liquid inlets and outlets. . The area of the heat transfer surface is the same in both test pieces.

Both of these test pieces S and R are immersed in a constant temperature bath 23 kept at 5 ° C. by a liquid cooling device 24, and a pipe equipped with a pump 25, a flow passage opening / closing cock 27, a pressure gauge 26 and a flowmeter 30. Thus, the inlets of the test pieces S and R are connected to the storage tank 29 for storing the saturated alum aqueous solution kept at 60 ° C. by the heater 33, and the outlets of both test pieces are connected to the pressure gauge 28. The storage pipe was similarly connected to the storage pipe.
When the flow rate of the alum aqueous solution flowing through the test piece was 1.5 liters per minute, 2.5 liters per minute, and 3.5 liters per minute, the pressure loss with the passage of time (every 10 to 20 minutes) ( The differential pressure between the pressure gauges 26 and 28) was measured. Results are shown in FIG.

As is apparent from FIG. 5, the pressure loss of the round heat exchange plate is smaller than that of the square heat exchange plate, and in particular, when the flow rate exceeds a certain limit, the pressure loss is almost zero. Does not change over time.

Table 1 shows the calculated time constant T (T = 1 / b) from the curve obtained in FIG. 5 using the pressure loss P as an exponential function of the time t (see FIG. 5). Time constant T
Shows quantitatively the difficulty of clogging of the heat exchanger, and Table 1 clearly shows the superiority of the round plate heat exchanger.

Table 1 Time constant (min) ―――――――――――――――――――――――――――――――― 1.5 liters per minute 1.5 liters per minute 2.5 liters 3.5 liters per minute ―――――――――――――――――――――――――――――――― Square 37 74 74 Round 79 94 ∞ ――――――――――――――――――――――――――――――――

[Brief description of drawings]

FIG. 1 is a partially omitted sectional explanatory view showing an example of a heat exchanger according to the present invention.

FIG. 2 is an explanatory view showing an example of a heat exchange plate of the heat exchanger of the present application.

3 is a cross-sectional view taken along line BB in FIG.

FIG. 4 is an explanatory diagram showing an outline of an effect verification device for a heat exchange plate according to the present invention.

FIG. 5 is a graph showing changes over time in pressure loss between the heat exchange plate according to the present invention and the conventional heat exchange plate.

FIG. 6 is an explanatory view showing an example of a conventional heat exchange plate.

[Explanation of symbols]

 1 Plate Heat Exchanger 2 Front Frame Plate 3 End Frame Plate 5 First Fluid Inlet 6 Second Fluid Inlet 10 Heat Exchange Plate 11 Peripheral Edge 12 Rising Edge 13 Herringbone Protrusion 14 Heat Transfer Surface 15a First Fluid Inlet 15b First Fluid outlet 16a Second fluid outlet 16b Second fluid inlet 18 Passage area

Claims (2)

[Claims] 1. A plurality of heat exchange plates are contacted in a gas- and liquid-tight manner in a gas-tight manner, and the flow paths of a first fluid and a second fluid to be heat-exchanged between the heat exchange plates are adjacent to each other. In the plate heat exchanger provided alternately, the heat exchange plates are provided with heat transfer surfaces on a substantially circular flat plate, and a pair of fluid passages for the first fluid are sandwiched between the heat transfer surfaces. An opening and a pair of fluid passage openings for the second fluid, wherein each of the two pairs of passage openings opens in the vicinity of the peripheral edge of the flat plate so that the peripheral edge of the flat plate extends from the opening. A plate-type heat exchanger, characterized in that a fluid directed toward is guided in a circumferential direction along a peripheral edge of a flat plate forming an arc. 2. The fluid passage opening has a substantially elliptical shape extending along the peripheral edge of a flat plate having an arc, and the heavy contact portions of the heat exchange plates adjacent to each other are integrally joined by brazing. The plate heat exchanger according to item 1.