JPS5934272B2 - Plate heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plate heat exchanger, and its purpose is to combine at least two types of plates of the same shape having heat transfer surfaces with different characteristics, and to achieve a heat exchanger with a minimum number of plates. In addition to the desired heat transfer characteristics, the configuration allows optimal selection of specification conditions such as the setting of the inlet or outlet temperature of the liquid to be treated and the medium, the size of the average temperature difference, the amount of heat exchange, or the size of the pressure loss. This is what we are trying to provide.

Conventional plate heat exchangers have a structure in which many heat transfer plates of one type are stacked one on top of the other, but among their characteristics, the correlation among flow velocity, pressure loss, and heat transfer rate is fixed. However, in order to obtain various delicate heat transfer characteristics and specification conditions, the number of plates has to be increased, resulting in an economical burden.

Generally, plate heat exchangers must satisfy flow conditions as well as heat transfer conditions.

Depending on the specifications, there are cases where it is necessary to lower the flow rate and sacrifice the overall heat transfer coefficient in order to satisfy the pressure loss.

At this time, the heat transfer area (ie, the number of plates) increases.

The following methods are generally used to reduce the heat transfer area.

Rearranging equations (1) and (2), in the above equation, q: heat transfer equation U: overall heat transfer coefficient W: flow rate
A: Heat transfer area C: Specific heat NTU: Number of transfer units T1-T2
Two temperature changes Δt: Average temperature difference Equation (3) is called the number of transfer units and is used to judge heat transfer performance.

The right side shows the conditions of the heat exchange process. The left side shows the performance characteristics of the heat exchanger.

1 represents the entire device, but this is one flow path, IC It can be broken down into performance per pass.

That is, if the number of parallel plates is R for both the high-temperature side and low-temperature side channels, the total number of plates is 2R+1, so if the heat transfer area per plate is a, the heat transfer area is (2R-
1) Become Xa.

(Since both end plates are not involved in heat transfer, 2R+1-2
becomes a heat transfer plate.

) The flow rate of one channel is π, and if this is W, then (NT
In Up, P is the NTU -T value per plate) -'-" - When the process condition of -NTU = 2.0 is given, a plate with a heat transfer performance of NTUp = 2.0 If there is, it will be a one-pass configuration and the number of sheets will be the minimum.

If the plate has NTUp=1.0, it will have a two-pass configuration and the number of plates will increase.

Also, when the process condition is NTU=1.0, NTUp
If you apply a plate with '= 1.0, the minimum number will be in ■pass, but if you apply one with NTUP = 2.0,
Due to pressure loss, the number of plates increases and there is too much margin, resulting in a larger heat transfer area than in the case where NTUp=1.0.

In the end, the minimum number of plates is NTUp, which matches NTU.

However, all NTUs differ in process conditions, and it is economically undesirable to prepare all NTUP plates that meet these conditions.

NTUp can be easily changed by changing the shape, arrangement method, number of arrangement, etc. of the heat transfer portion protrusions.

It goes without saying that it is economical to change the shape of the heat transfer surface while keeping the dimensions of the plate and gasket constant.

Figure 3 shows the flow rate and heat transfer performance characteristics per plate passage.
This indicates UP.

At the flow rate X point, plate A shows NTUp=2.0, and plate B shows 1.0.

By combining A and B, intermediate performance can be achieved.

By changing the ratio of group A and group B, NTUP=1 to 2 can be arbitrarily selected.

It is possible to always use the minimum number of heat exchangers depending on the process conditions.

The present invention addresses the above-mentioned problems, and uses two or more types of plates that are combined and organized to form one plate heat exchanger. Its configuration will be explained.

A and B indicate different types of plate groups, in which at least two types of identical plates 1 and 2 having different heat transfer characteristics are used, and a plurality of plates of each type are stacked together via a gasket.

The term "same-shaped plates" as used herein refers to plates that have the same outer shape, gasket shape, and the positions and dimensions of the four corner holes.

Reference numeral 3 denotes a play plate, which is composed of at least one plate in which different types of plate groups A and B face each other.

One plate or two plates from a group of different types of plates facing each other, or one plate or two plates from both groups of different types of plates are selected as play plates.

Different types of plate groups AB, A, and BC are respectively joined and integrated via play plates 3 to constitute one plate heat exchanger.

Figure 1 shows the case where two or three different types of plate groups are combined in different proportions depending on the desired heat transfer characteristics and specification characteristics. A
It exhibits intermediate characteristics of the B dissimilar plate, with the ratio of 70:30 being approximately 70:30, and the characteristics of 8 and B being dominant, respectively.

In the second case, three different types of plate groups L2 and L4 are used.

2A and 2C show an example of a flow path configuration, in which a common section 5 or an independent section 6 is formed with the play plate 3 in the center as a boundary.

In Figures 4 to 9, plates 1 and 2 of the same shape each having a heat transfer surface with different characteristics are provided with one or two play plates 3, and a large number of plates 1 and 2 are stacked alternately through gaskets, each having a different flow rate. This shows an example of a road configuration.

In Figure 4, liquid a flows through plates 1°2 in series, and liquid b
Liquids C and C were provided so as to independently exchange heat with liquid A via the play plate 3 (see the opening in Figure 2).

The play plate 3 was made into a space 7, and the periphery of the opening through which liquid a penetrated was sealed with a gasket.

In FIG. 5, both a and liquid are introduced in series from the left and right, and heat is exchanged in a common section (see the opening in FIG. 2).

The play plate 3 is a space 7, and the plate 1 is separated from this space.
, 2 have different heat transfer characteristics.

FIG. 6 shows an example of heat exchange between the AB liquid and the CD liquid using the play plate 3 as a boundary.

Liquid A is introduced into the play plate to form a filling part 8, but it is not allowed to flow (see the opening in Figure 2).

The reason why liquid A is filled in this way is that when there is a pressure difference across the play plate, the filling part 8 is filled with liquid A, so there is no risk of plate distortion, etc., and the tightening and sealing effects are ensured. This effect is observed.

FIG. 7 shows a case where two play plates 3 are interposed, each of which is filled with a liquid.

FIG. 8 shows a case where the play plate 3 in the case of FIG. 5 is filled with liquid a.

FIG. 9 shows a case where independent heat exchange is performed via play plates 3.

Since the plate heat exchanger of the present invention has the above-mentioned configuration, all plates of the same shape can be combined and fixed together as one heat exchanger through gaskets, and different types with different NTUp can be connected through play plates. Plate group AB or BC
etc. are formed, so that the heat medium and other fluids passing through these plates can obtain the desired heat transfer characteristics, and can also be configured as a common section through play plates or as independent sections. Depending on various conditions, the maximum
It also has the effect of providing an economical heat exchanger.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a plate heat exchanger showing an example of a combination of different types of plates, Figure 2 is an explanatory diagram of the flow path configuration, and Figure 3 is a diagram showing flow rates and heat transfer performance characteristics. The graphs and FIGS. 4 to 9 are explanatory diagrams of the stacked state of plates and the flow path configuration. L2, 4... Same-shaped plate, 3... Play plate, 5... Common section, 6...
Independent section; 7... Spatial section, 8...
...Filling section.

Claims (1)

[Claims] 1. At least two types of identical plates having heat transfer surfaces with different characteristics are used, and a plurality of plates of each type are stacked together via a gasket to form a group of different types of plates. A plate heat exchanger in which at least one facing plate is used as a play plate, and the two plates are joined and integrated, and the play plate is used as a boundary to configure independent sections or a common section with different heat transfer characteristics. 2. The plate heat exchanger according to claim 1, wherein a space is formed between a plate serving as a play plate for joining a group of dissimilar plates and a plate facing the plate without introducing a fluid. 3. A heating medium fluid is introduced between a plate serving as a play plate for joining a group of dissimilar plates and a plate facing the same to form a filling portion, but does not flow. Plate heat exchanger. 4 With the play plate that joins the different types of plates as a boundary, 2
A group of plates having different heat transfer characteristics are configured, one fluid is connected in series so as to form a common section, and the other fluid is configured to form an independent flow path through a play plate. The plate heat exchanger according to item 1. 5. A claim in which a group of different types of plates are joined together via a play plate to form two types of plate groups with different heat transfer characteristics, and both fluids undergoing heat exchange are connected in series via the play plate. The plate heat exchanger according to item 1.