JPH073164Y2 - Plate fin type heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to an improvement of a plate fin type heat exchanger for recovering high-temperature exhaust heat. The outermost layer passage has no dummy passage for flowing a small amount of fluid. The present invention relates to a plate fin type heat exchanger in which thermal stress generated in a tube plate is relaxed.

2. Description of the Related Art A plate fin type heat exchanger has a large heat transfer area per unit volume and a high heat transfer coefficient, and thus has an advantage that it can be easily made compact as compared with other types, particularly a tube type heat exchanger.

In addition, the plate fin type heat exchanger has a wide selection range in design, such as the fin pitch, fin height, and fin shape that are suitable for the properties of the fluid flowing down each passage and the purpose, and so on. Is also used in a wide variety of applications because it can be arbitrarily selected and can be efficiently designed.

Problems to be Solved by the Invention As shown in FIG. 6, fins (2) are interposed between tube plates (1) and (1) to close a required portion with a spacer bar (3) to form a fluid passage in a required direction. In a plate fin type heat exchanger in which a required number of these fluid passages are stacked and the side plate (4) is placed in the outermost layer and integrated by brazing, a high temperature side fluid passage and a low temperature side fluid passage in countercurrent arrangement are provided. No heat exchange between gas / gas, liquid / gas, liquid /
When used as a heat exchanger for recovering waste heat of liquids, for example,
When the passage on the side of the outermost side plate (4) is the high temperature side fluid passage (H) and the low temperature side fluid passage (C) is arranged via the tube plate (1), the high temperature side fluid temperature is particularly 350. When the temperature is as high as ~ 800 ° C, there is a temperature difference between the side plate (4) and the tube plate (1) as shown in Fig. 2b.
Due to the difference in thermal expansion, as shown in FIG. 2a, the tube plate (1) having a relatively low temperature works to pull back the expansion of the side plate (4) having a relatively high temperature in the width direction of the channel, and the tube between the both channels is returned. It was found that high stress is generated near the spacer bar (3) of the plate (1).

In addition, as shown in FIG. 3b, when the outermost passage is configured as a dummy passage (D) in which no fluid flows, there is a temperature difference between the uppermost tube plate (1) and the tube plate (1 '), Adjacent low temperature side fluid passage (C) as shown in Fig. 3a
A high stress is generated near the spacer bar (3) of the tube plate (1 ').

In view of the above problems of a plate fin type heat exchanger that recovers high temperature exhaust heat, the present invention is a plate fin type heat exchanger having a configuration capable of relieving high stress generated in a tube plate due to a large temperature difference between fluid passages. The purpose is to provide an exchange.

Means for Solving the Problems The present invention is directed to forming fins between tube plates to form fluid passages in a desired direction with a spacer bar and stacking the fluid passages so that heat is generated between adjacent high temperature fluid passages and low temperature fluid passages. In the plate fin type heat exchanger to be exchanged, the outermost layer passage is different from the fluid flowing in the adjacent passage, that is, a small amount of high temperature side or low temperature side fluid which should originally flow for heat exchange flows down depending on the fluid temperature in the adjacent passage. If the dummy passage, for example, the passage adjacent to the outermost layer passage is the low temperature side fluid passage, the high temperature side fluid that should originally flow for heat exchange, and if it is the high temperature side fluid passage, the low temperature side fluid flows down a small amount. It is a plate fin type heat exchanger characterized in that it is a dummy passage.

Function When the outermost layer of the plate fin type heat exchanger is originally a high temperature side fluid passage, the present invention does not constitute a structure in which the fluid does not flow at all like a complete dummy passage, but a normal high temperature side passage. By adopting a dummy passage structure in which the flow rate is smaller than that of the fluid passage, the temperature change between the side plate and the tube plate can be reduced, the deformation of the tube plate becomes gentle, and the thermal stress is relieved.

The amount of fluid flowing through the dummy passage according to the present invention is appropriately selected in consideration of the conditions of the heat exchanger core, the fluid temperature difference, etc. so as not to impair the effect of reducing the temperature change between the side plate and the tube plate. It is necessary to restrict the inlet and outlet of the dummy passage for adjusting the flow rate as in the embodiment, and also to make the fins in the passage high pressure loss.

In addition, as for the effect, the higher the fluid temperature on the high temperature side, the more remarkable the stress relaxation effect is.
Therefore, it is extremely effective at high temperatures and is most suitable as a heat exchanger for gas turbine regenerators and a heat exchanger for exhaust heat recovery of high-temperature exhaust gas.

This invention can be applied to any plate fin type heat exchanger, such as different materials for plates, different fin shapes, number of stacked stages, parallel flow arrangement, cross flow arrangement, countercurrent arrangement, stacking several dummy passages, etc. It can also be applied to the case of the configuration and has the same effect.

EXAMPLE The heat exchanger core (10) shown in FIG. 1 has the same structure as the plate fin type heat exchanger having the countercurrent arrangement shown in FIG. 6 and is for recovering heat from the high temperature side fluid at 600 ° C. It has a multi-layer structure made of stainless steel (SUS304).

More specifically, in the configuration in which the passage on the side plate (4) side of the outermost layer is originally the high temperature side fluid passage (H), as shown in FIG. 5a, an opening is formed on the outlet side of the outermost layer passage in the center of the passage width. The spacer bar (5) provided is provided, or is provided at the inlet side as shown in FIG. 7B, or is provided at both the inlet and outlet of the passage as shown in FIG. 3C so that a small amount of high temperature side fluid flows through the outermost layer. It is configured in a high temperature dummy passage (HD). Further, as shown in FIG. 5, the opening of the passage is provided at the center of the passage width because only the corrugated fins (2) are present in the central portion through which the high temperature fluid passes, and the spacer bar (5) having a large heat mass is provided. ) Exists only at a part of the outlet or inlet of the passage, the temperature difference between the high temperature fluid passage opening and its surroundings becomes small, and the thermal stress generated in the tube plate (1) can be made small.

However, when the openings of the passages are provided on both sides of the passage width, one of the high temperature fluids passes where it contacts the spacer bar (3), so that the difference in heat mass between the corrugated fins (2) and the spacer bar (3) is increased. Since it is large, the temperature difference becomes large and the thermal stress generated in the tube plate (1) becomes large.

In the high temperature dummy passage (HD), the opening width of the spacer bar (5) is selected as a required width, and the passing fluid amount is set to a required amount according to the heat balance with the fluid in the adjacent passage. In addition, when the outermost layer is originally the low temperature side fluid passage (C),
A low temperature dummy passage is provided with the same configuration.

This high temperature dummy passage (HD) is a tube plate (1)
Although the low temperature side fluid passage (C) is disposed adjacent to the low temperature side fluid passage through the passage, a small temperature change between the side plate (4) and the tube plate (1) due to a small amount of high temperature side fluid flowing in the passage. Therefore, thermal stress can be relaxed.

In the outermost tube plate (1) of the high temperature dummy passage (HD), even if the temperature change becomes large, the temperature between the side plate (4) and the tube plate (1) is the same as the one-dot chain line in FIG. As shown in FIG. 2 and FIG. 3, the temperature becomes almost the intermediate temperature, and the stress of pushing down as shown in FIG. 2a and the stress of pushing up as shown in FIG. Has the effect of relieving stress.

That is, the temperature distribution diagram of the side plate (4) and the tube plate (1) between both passages of the heat exchanger core (10) shows the high temperature dummy passage (HD) according to the present invention as shown in FIG. By providing the tube, the temperature difference can be reduced as shown by the broken line as compared with the case of the prior art in FIG. 2 (solid line) and the case of FIG. 3 in which the complete dummy passage (D) is provided (solid line). The deformation generated by the high stress near the spacer bar (3) of the plate (1) becomes gentle, and the stress is relieved.

Effect of the Invention This device reduces the temperature change between the side plate and the tube plate by using a dummy passage for passing a small amount of fluid in the outermost layer passage, and reduces the temperature change between the side plate and the tube plate, as shown in FIG. The deformation that was caused by the extremely high stress becomes gentle, and the stress is relieved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a passage structure and a temperature distribution of a plate fin type heat exchanger core according to the present invention. 2A and 2B, and FIGS. 3A and 3B are explanatory views showing the passage configuration and temperature distribution of the conventional plate fin type heat exchanger core. FIG. 4 is an explanatory view showing a passage structure and a temperature distribution of the plate fin type heat exchanger core according to the present invention. FIGS. 5a, 5b and 5c are explanatory views showing the structure of the dummy passage according to the present invention. FIG. 6 is a perspective explanatory view showing an example of a conventional plate fin type heat exchanger. 1,1 '... Tube plate, 2 ... Fins, 3 ... Spacer bar, 4 ... Side plate, 5 ... Spacer bar, H ... High temperature side fluid passage, C ... Low temperature side fluid passage, D ... … Dummy passage, HD …… High temperature dummy passage.

Claims (2)

[Scope of utility model registration request] 1. A plate fin type heat exchanger in which fins are interposed between tube plates to form fluid passages in a desired direction by spacer bars, and the fluid passages are stacked and heat is exchanged between adjacent high temperature side fluid passages and low temperature side fluid passages. In the exchanger, the plate fin type heat exchanger is characterized in that the outermost layer passage is a dummy passage for allowing a small amount of a high temperature side or low temperature side fluid different from the fluid flowing in the adjacent passage to flow down. 2. The plate fin type heat exchanger according to claim 1, wherein the dummy passage of the outermost layer is a high pressure loss passage.