JPH0833286B2 - Plate type heat exchanger - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate heat exchanger having two fluid passages, and particularly, it can be used without trouble even when it is necessary to avoid mixing fluids. Plate type heat exchanger.

2. Description of the Related Art As shown in FIG. 3, a conventional plate heat exchanger has two fluid passages (A) and (B) via heat transfer elements (p) and (p ') each including one heat transfer plate. ) Are adjacent to each other, and heat exchange between fluids is indirectly performed via the heat transfer element, as is well known. As an example of the plate heat exchanger, the one described in JP-A-61-212493 can be mentioned.

Problems to be Solved by the Invention Since the plate heat exchanger has a structure in which a large number of heat transfer elements are layered, even if a hole is opened in the heat transfer wall due to corrosion or the like, it cannot be easily found. However, there arises a disadvantage that the heat medium is mixed into the drinking water to be treated.

Therefore, in order to guarantee the liquid quality, it is required to detect such abnormalities in advance and prevent the mixing of different fluids. However, in the tube type heat exchanger, the heat transfer tubes are doubled and a gap is provided between the double partition walls so as to confirm water leakage (actual exploitation 57- 120874 publication).

However, the efficiency of heat transfer through the double partition walls and in the presence of air between both partition walls is very poor, and the heat transfer performance is sacrificed, which impedes practical application. It is a thing.

Therefore, the present invention is intended to solve the problems as described above, that is, while ensuring the desired heat transfer performance, even if a hole is opened in the heat transfer wall due to corrosion or the like, the fluid will not flow. It is an object of the present invention to provide a plate heat exchanger that does not mix with each other.

Means for Solving the Problems The present invention relates to a method in which heat is exchanged between fluids in two adjacent fluid passages via a heat transfer element, and the heat transfer element is provided between a pair of heat transfer elements. In the one in which heat exchange is performed in, the heat transfer element is composed of a pair of heat transfer plates, and the heat transfer plates are brought into contact with each other leaving a gap that is not watertight, and at the outer periphery, the gap is opened to the outside. By water-tightly joining around the through-hole serving as the entrance and exit of the above, providing a water injection port and a drain receiver in communication with the gap, and partially brazing the heat transfer parts of the pair of heat transfer plates to each other. This is a solution to the above problem.

Using the open gap left between the heat transfer plates,
If necessary, it is possible to confirm the presence or absence of leakage by passing water or the like.

Heat exchange between fluids is indirectly performed via the heat transfer element, but the gap between the heat transfer plates that make up the heat transfer element is not watertight, so heat transfer performance is not significantly impaired. . Further, the heat conductivity of the heat transfer plate is improved by brazing, and the heat transfer performance is positively secured.

EXAMPLE An example shown in the drawings will be described with reference to FIGS.
3A and 3B are front views of the heat transfer elements P, P ', respectively. As shown in FIG. 1, these heat transfer elements P, P'are alternately laminated in a predetermined number according to the specifications. A plate heat exchanger is constructed.

Each heat transfer element (P) (P ') is composed of a pair of heat transfer plates (12) (14) of the same shape, and the heat transfer plates (12) (14) are in contact with each other but are not watertight to each other. Gap (1
6) is left, and this gap (16) is open to the outside. The drawing shows the gap (16) in an exaggerated manner. The heat transfer element (P) (P ') has fluid inlets / outlets (18) (20) (22) (24) at four corners, and a heat transfer plate ( 12) (1
4) is watertightly joined by brazing or other suitable means so that the heat exchange fluid does not flow into the gap (16).

Further, in order to positively secure the heat transfer performance by increasing the thermal conductivity of the heat transfer element (P) (P '), the reference numeral (32)
Heat transfer plates (12) and (14) are brazed to each other at points indicated by. FIG. 2A shows an example of brazing in the corrugated direction of the heat transfer section, and FIG. 2B shows an example of brazing in the vertical direction.
In addition to this, various patterns such as brazing at scattered points can be adopted. In either case, instead of joining the heat transfer parts over the entire surface, the gap (16)
Is partially brazed to allow the fluid to flow down.
It goes without saying that a brazing material with high thermal conductivity should be selected. This brazing increases the rigidity of the heat transfer element, which is advantageous in terms of strength.

The heat transfer plates (12) and (14) are formed by corrugating a central heat transfer portion that substantially participates in heat transfer. This is because the corrugations of the adjacent heat transfer elements (P) and (P ') are cross-butted to each other to maintain the space between the heat transfer elements and to promote the turbulent flow of the fluid to improve the heat transfer efficiency. However, it is not essential to the present invention, and it is of course possible to adopt various other shapes.

Adjacent heat transfer elements (P) and (P ') are joined by brazing or other suitable means around the heat transfer section and around the fluid inlet and outlet, as indicated by reference numerals (28) and (30), respectively. Or a gasket is provided to prevent fluid from leaking out of the vessel and mixing with each other. Incidentally, as described in the above-mentioned JP-A-61-212493, the outer peripheral edge of the heat transfer element may be bent so as to polymerize in a so-called nested manner.

Next, referring to FIG. 1, to describe the flow of each fluid when heating the liquid to be treated with the heat medium, the heat medium is introduced from the heat medium inlet (18) of the heat transfer element (P) (P '). It flows into the passage (A) between the heat transfer elements (P) and (P ') and then flows out through the heat medium outlet (20). The liquid to be treated is the liquid to be treated inlet (22) of the heat transfer element (P) (P ').
Flow into the passage (B) between the heat transfer elements (P) and (P ′), and then flow out from the liquid outlet (24) to be treated. Then, the liquid to be treated receives heat from the heat medium via the heat transfer elements (P) and (P ') while flowing through the adjacent passages (A) and (B), and the temperature thereof rises. At that time, the heat transfer plates (12) (14) constituting the heat transfer elements (P) (P ')
Since they are not in close contact with each other, their heat transfer coefficient is slightly inferior to that of a single sheet, but they do not significantly impair heat transfer performance as compared with a double partition wall in which a complete air layer is interposed. In addition, since the brazing (32) portion effectively acts on heat conduction, it is possible to secure a predetermined heat transfer performance.

When conducting a leak test, the heat transfer plate (12)
It is sufficient to pour a constant flow rate of water into the gap (16) between the (14) without pressure and check whether all the water escapes. For that purpose, it is preferable to provide a water inlet, a header, and a drainage receiver (none of which are shown).

EFFECTS OF THE INVENTION According to the present invention, a plate-type heat exchange having a structure capable of confirming perforation due to corrosion of a heat transfer plate and preventing fluid leakage or mixture while ensuring a predetermined heat transfer performance. You can get a vessel. Therefore, from the viewpoint of liquid quality assurance, a significant effect is recognized in enabling the practical application of the plate heat exchanger in the field where such measures are required.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a plate heat exchanger schematically showing an embodiment of the present invention, and FIGS. 2A and 2B are schematic front views of heat transfer elements of the plate heat exchanger of FIG. 2A is a view as seen from a passage A, FIG. 2B is a view as seen from a passage B, and FIG. 3 is a schematic diagram for explaining a conventional plate heat exchanger. P, P ': Heat transfer element A, B: Fluid passage, 12, 14: Heat transfer plate, 16: Gap 32: Brazing part.

Claims (1)

[Claims] 1. A heat transfer element comprising a pair of heat transfer plates, wherein heat is exchanged between fluids in two fluid passages adjacent to each other via the heat transfer element. The gaps that are not watertight are left in contact with each other, and the gaps are opened to the outside at the outer periphery, and the gaps are watertightly joined around the through holes that serve as fluid inlets and outlets, and a water inlet and a drain receiver are provided in communication with the gaps. And a plate type heat exchanger in which the heat transfer portions of the pair of heat transfer plates are partially brazed to each other.