JPH01171602A - Heat-transmitting plate element for plate type flowing liquid film evaporator - Google Patents

Abstract

PURPOSE:To obtain an improved evaporation efficiency by keeping a distance between heat-transmitting plates and strength of the heat transmitting plates against pressure with horizontal grooves and vertical projections and forming thin films by dispersing a liquid to be heated and introducing the dispersed liquid. CONSTITUTION:Plural numbers of long row of small corrugated grooves 2 are formed in the perpendicular direction to heat-transmitting plates 1 having corrugated horizontal sectional shape, and horizontal deeper grooves 3 than the small corrugated grooves 2 are formed at a heated fluid side along the vertical direction with an appropriate distance and orthogonally to the small corrugated grooves 2. Further, vertical projections 4 having high wave-height are formed parallel to the small corrugated grooves 2 in the horizontal direction with an appropriate distance. The heat- transmitting plates 1 are superposed by allowing to face each other alternately to form thus a heat-transmitting plate element. By this constitution, the strength against pressure of the heat-transmitting plate is kept, and redispersion and distribution of liquid film are permitted, and satisfactory thin liquid films are formed on over the whole surface of heat-transmitting plates. Thus, evaporation performance is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat transfer plate element for a falling film type evaporator, concentrator, multiple effect tank, seawater desalination device, etc. using a plate heat exchanger. Regarding the improvement of

[Conventional technology]

As shown in FIG. 7, the heat transfer plate element of a conventional plate-type falling film evaporator is a heat transfer plate having a vertical corrugation 12 and a plurality of rows of uncorrugated band-shaped portions 13 perpendicular to the corrugation 12. 11 are alternately stacked facing each other to form a tubular passage 14 through which the heated fluid passes and a gap-like passage 15 through which the heated fluid passes, and small wavy grooves 22 are formed as shown in FIG. There is a method in which the heat transfer plate 21 is provided with appropriate irregularities or spacers 23, 24 to maintain the interval between the heat transfer plates and allow the fluid to be heated and the heating fluid to flow alternately.

These heat transfer plates are sealed with welding or gaskets at the horizontal end on the side where the heated fluid flows, and at both upper and lower ends on the side where the heating fluid flows, to limit the passages through which each fluid flows. are doing. In order to increase the evaporation efficiency in such a heat transfer plate element, the heated fluid is dispersedly introduced from above to form a thin film, and heat is transferred by the heated fluid that flows in from the horizontal direction of adjacent passages through the heat transfer plate. Heat through a plate and evaporate. The generated steam and the unevaporated heated fluid flow out from below.

[Problem that the invention seeks to solve]

In a falling liquid film evaporator, it is necessary to form as thin a liquid film as possible over the entire heat transfer surface on the side of the heated fluid to increase the efficiency of evaporation. In addition, in the case of a plate type, unevenness and spacers are provided in order to maintain the pressure resistance of the heat transfer plate against the pressure difference between the fluids and the intervals between the fluids.

However, when the load is low, the heat transfer plate element shown in FIG. 7 is difficult for the fluid to be heated because the fluid collects at the bottom of the valleys of the waveform 12, the peaks do not dry easily, and a good thin film is formed over the entire surface. There was a problem in that it was difficult to obtain sufficient evaporation performance due to the formation of the groove, and there was also a problem in that pressure loss was large due to the fluid flowing in a wave shape on the heated fluid side forming the gap-shaped passage 15. .

In addition, the heat transfer plate element shown in FIG. 8 has better heat transfer performance than the above-mentioned one and has less pressure loss on the heated fluid side, but as the heated fluid moves downward, the small wavy grooves 2
The problem is that the top of the liquid dries out and the flow direction is disturbed by the protrusions 24, causing the liquid to flow unevenly, making it difficult to form a good thin film over the entire surface and resulting in insufficient evaporation performance. Ta.

The present invention has been made in view of the current situation, and it allows the heat transfer plate to maintain the strength against the pressure difference between two fluids and the distance between the fluids to flow, and to improve the flow of the heated fluid distributed over the entire heat transfer surface. The object of the present invention is to provide a heat transfer plate element that can form a thin film and has high evaporation efficiency.

[Means for solving problems]

The present invention is formed by stacking a plurality of heat transfer plates, and allows a fluid to be heated to flow in a thin film from above to below in vertical passages of passages that are adjacent to each other and substantially perpendicular to each other through the heat transfer plates, while horizontally In a heat transfer plate element of a plate-type falling film evaporator that evaporates a heated fluid by flowing a heating fluid through a directional passage, the cross-sectional shape in the horizontal direction is wavy and has a plurality of rows of small wavy grooves that are long in the vertical direction. horizontal grooves that are deeper than the small wavy grooves orthogonal to the plurality of rows of small wavy grooves at appropriate intervals along the vertical direction on the heated fluid side, and horizontal grooves between the plurality of rows of small wavy grooves; A plurality of heat transfer plates having vertical protrusions that are longer in the vertical direction and have a higher wave height than the plurality of rows of small wavy grooves provided at appropriate intervals along the wafer are formed by alternately stacking each other facing each other. The present invention proposes a heat transfer plate element for a plate-type falling film evaporator, which is characterized by the following.

[Effect]

The fluid to be heated that disperses and flows in from above forms a thin film on the surface of the small wavy grooves between the vertical protrusions and flows down while evaporating. It disperses, forms a thin film over the entire surface of the small wavy grooves, and flows down.
Repeat this. The small wavy groove increases the heat transfer coefficient, and the horizontal groove plays the role of redistributing the heated fluid, maintains the distance between the heat transfer plates on the heating fluid side, and the heat transfer plate in the small wavy groove part Provides compressive strength. In addition, the vertical protrusions maintain the spacing between the heat transfer plates on the heated fluid side, support the pressure resistance of the horizontal grooves, and limit the flow path of the heated fluid that first disperses and flows in, allowing the fluid to flow diagonally. Prevent it from shifting to one side.

〔Example〕

FIG. 1 is a partial front view of a heat transfer plate element according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line a-a in FIG. 1,
FIG. 3 is a sectional view taken along line bb in FIG. 1, and FIG. 4 is a partial perspective view of the heat transfer plate element of this embodiment. In Figs. 1 to 4, reference numeral 1 denotes a heat transfer plate having a wavy cross-sectional shape in the horizontal direction, and the heat transfer plate IK is provided with a plurality of rows of small wavy grooves 2 that are long in the vertical direction, and on the side of the heated fluid, Horizontal grooves 3 deeper than the plurality of rows of small wavy grooves 2 are provided at appropriate intervals along the vertical direction in a direction perpendicular to the small wavy grooves 2, and the wave height is higher than the plurality of rows of small wavy grooves 2. Vertical protrusions 4 are provided parallel to the small wavy grooves 2 at appropriate intervals in the horizontal direction.

These horizontal grooves 3 and vertical protrusions 4 are arranged so that when the heat transfer plates 1 are alternately stacked facing each other, the vertical protrusions 4 are in a respectful υ relationship with each other on the heated fluid side, and the horizontal grooves 3 are on the heated fluid side.
The back surfaces of the heat transfer plates 1 are arranged so that they overlap each other υ, and between the heat transfer plates 1 alternately, there are a plurality of vertical passages 5 having a rectangular cross-sectional shape, and a plurality of horizontal passages 6 having a rectangular cross-sectional shape. are formed and are adjacent to each other with the heat transfer plate 1 interposed therebetween and are perpendicular to each other. Both horizontal ends of the heat transfer plate 1 are connected to the vertical passage 5 side, and the heat transfer plate 1 is connected to the horizontal direction passage 6 side.
The upper and lower ends of the tube are sealed by welding or gaskets, respectively, to limit the flow direction of the heated fluid and the heating fluid. 5 and 6 are partial perspective views of other embodiments of the heat transfer plate element of the present invention.
In order to prevent the comrades and the vertical protrusions 4 from overlapping each other, FIG. 3 and a vertical protrusion 4 are arranged. In such a heat transfer plate element, the heated fluid flows into the vertical passage 5 in a distributed manner along the wall surface of the heat transfer plate 1, forms a thin film on the surface of the small wavy grooves 2, and flows down the heat transfer plate 1. The heating fluid flowing into the adjacent horizontal passage 6 is heated through the heat transfer plate 1 and evaporated. The small wavy grooves 2 increase the heat transfer area, and the liquid is drawn to the valleys by surface tension, making the liquid film at the top thinner, thereby increasing the heat transfer coefficient and promoting effective flow of the liquid film. . However, the liquid film goes to the bottom and collects in the valleys of the small wavy grooves 2, causing the top to dry.
The effect of increasing the heat transfer coefficient by the top thin film will be diminished. It also flows in a diagonal direction and flows downward. Here, the horizontal groove 3 serves to redistribute the liquid film at the top of the small wavy groove 2 before it dries, and the vertical protrusion 4 serves to close both ends of the vertical passage 5 in the horizontal direction, allowing the liquid to flow in and disperse initially. It limits the flow path of the heated fluid, prevents the liquid film from running diagonally, improves the rectifying effect and the pressure resistance of the heat transfer plate. Therefore, the horizontal grooves 3 are designed so that the liquid film at the top of the small wavy grooves 2 can be redispersed before it dries, and a thin film can be constantly formed on the entire surface, and the pressure resistance of the heat transfer plate in the small wavy groove portions is taken into account. The distance between the vertical projections 4 is determined by taking into consideration the pressure resistance of the horizontal groove 3 and the initial degree of dispersion of the fluid to be heated. Furthermore, since the heating fluid can flow approximately straight through the horizontal passage 6, the pressure loss is also small.

In addition, in the above embodiment, the horizontal groove 3 and the vertical protrusion 4
Both are intermittent, but either one may be continuous.

As described above, according to the heat transfer plate element of the above embodiment, a thin film with a large heat transfer coefficient and suitable for evaporation is formed over the entire surface of the heat transfer plate, improving evaporation performance and reducing pressure loss of the heated fluid. .

〔Effect of the invention〕

According to the heat transfer plate element of the present invention, the horizontal grooves and vertical protrusions maintain the heat transfer plate spacing and the pressure resistance of the heat transfer plates, and also serve to redistribute and rectify the liquid film, so that the entire surface of the heat transfer plate is A unique effect is that it can create a good thin film suitable for evaporation over a wide range of conditions, and that the effect of increasing the heat transfer coefficient due to the small wavy grooves can be maintained stably from low to high loads, improving evaporation performance. play.

[Brief explanation of the drawing]

FIG. 1 is a partial front view of an embodiment of the heat transfer plate element of the present invention, FIG. 2 is a sectional view taken along line a-a in FIG. 1,
FIG. 3 is a sectional view taken along line bb in FIG. 1, and FIG. 4 is a partial perspective view of this embodiment. 5 and 6 are partial perspective views of other embodiments of the heat transfer plate element of the present invention, and FIGS. 7 and 8 are partial perspective views of a conventional heat transfer plate element. DESCRIPTION OF SYMBOLS 1...Heat transfer plate, 2...Small wavy groove, 3...Horizontal groove, 4...Vertical direction protrusion, 5...Vertical direction passage,
6...Horizontal passage, 11...Heat transfer plate, 12
...Waveform, 13...Striped portion without waveform, 14...
- Tubular passage, 15...Gap-like passage, 21...Heat transfer plate, 22...Small wavy groove, 23.24...Irregularities or spacer. Agent: Patent attorney Akira Sakama (2 persons)
Two bad guys

Claims (1)

[Claims] A plurality of heat transfer plates are formed by stacking each other, and a fluid to be heated is caused to flow in a thin film from above to below in the vertical passages of the passages adjacent to each other and substantially orthogonal to each other through the heat transfer plates, while flowing in the horizontal passages. In a heat transfer plate element of a plate-type falling film evaporator that evaporates a heated fluid by flowing a heating fluid, its horizontal cross-sectional shape is wavy and has multiple rows of small wavy grooves that are long in the vertical direction. The fluid side has horizontal grooves that are deeper than the small wavy grooves and are perpendicular to the plurality of rows of small wavy grooves at appropriate intervals along the vertical direction, and horizontal grooves are formed between the plurality of rows of small wavy grooves. It is characterized in that a plurality of heat transfer plates are formed by alternately facing each other and overlapping each other, each having a vertically long protrusion having a higher wave height than the plurality of rows of small wavy grooves provided at appropriate intervals. Heat transfer plate element for plate type falling film evaporator.