JPS6210355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a direct-fired high-temperature regenerator, and more particularly to a direct-fired high-temperature regenerator (hereinafter sometimes simply referred to as a regenerator) used in an absorption refrigerator cycle.

The regenerator is a device that heats and concentrates a dilute lithium bromide (hereinafter referred to as LiBr) solution that has absorbed refrigerant vapor generated in the evaporator in an absorption refrigerator cycle to obtain a concentrated LiBr solution and refrigerant vapor. In the regenerator of an absorption refrigerator cycle that uses LiBr solution as the absorption liquid, the liquid temperature is 160°C or higher, and the LiBr concentration of the liquid is 60°C or higher.
It is concentrated to 65%, but as shown in Figure 1, LiBr
When the LiBr concentration of the solution is at the above concentration level (examples with LiBr concentrations of 62% and 65% are shown in the figure).
It has been confirmed that when the temperature exceeds 175°C, the rate of corrosion of metal increases rapidly.

In a general heat exchanger, in order to increase the heat exchange amount Q, the heat transfer area A, the heat transmission coefficient K, and the temperature difference ΔT are increased as shown in the following equation.

Q = K T
Efforts have been made to increase the amount of heat exchange while keeping the temperature below 15℃ (liquid temperature below 175℃), but in direct-fired regenerators that use high-temperature combustion gas, it is necessary to keep the temperature difference uniform throughout the entire chamber. It is difficult to Improvements such as miniaturization of regenerators have been progressing with the aim of improving performance and reducing production costs, but accidents due to local corrosion have been occurring one after another. There are drawbacks.

Figures 2 and 3 show conventionally used high-temperature regenerators. In these figures, fuel such as gas or kerosene is combusted in a burner 10, and high-temperature combustion gas 20 is passed through a furnace tube. 11, and after exchanging heat with the LiBr solution 21 in the smooth solution pipe 12 and the finned solution pipe 13, the chimney 15
is discharged outside the regenerator 1.

On the other hand, the LiBr solution 21 exchanges heat with the combustion gas in the furnace tube section and solution tube group section of the regenerator 1, and is boiled and concentrated.

The smooth solution tube 12 with a small heat transfer area is placed at the front of the solution tube group (near the furnace tube 11), and the finned solution tube 12 with a large heat transfer area is placed at the rear to make the amount of heat exchange as uniform as possible. It's for a reason. In addition, the rectifying plates 14a, 14
b and 14c are provided in order to prevent heat loss caused by the combustion gas 20 passing through the end portion 30 of the tube group.

However, in the conventionally known regenerator described above, it has been confirmed that local corrosion occurs due to the attack of high temperature gas on the solution tubes near the ends of the tube group.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a direct-fired high-temperature regenerator that is free from local corrosion.

The present inventors have discovered that one of the main causes of local corrosion is the non-uniformity of the amount of heat exchange in the cross-sectional direction within the regenerator, and in particular the local attack of high-temperature gas on the solution tubes near the ends of the tube group. The above object of the present invention has been achieved by confirming this through experiments and appropriately arranging a solution tube and a rectifying plate as a means for solving the problem.

The gist of the present invention is to provide reduced gas that is formed between the solution tubes and a rectifier plate provided at the end of the solution tube group in a direct-fired high-temperature regenerator consisting of a furnace cylinder section and a solution tube group section. A direct-fired high-temperature regenerator is characterized in that a space is provided immediately after a flow path.

The circumstances leading to the completion of the present invention will be explained below based on experimental results.

FIG. 4 shows the flow state of the combustion gas in the solution tube group. In this figure, most of the combustion gas flows through the center section 31 of the tube group, and a portion flows through the end portion 30 of the tube group. . The gas flowing through the end portion 30 of the tube group is not cooled due to little contact with the solution tube 12 and passes through as the high-temperature gas 22, while the gas flowing through the center portion 31 of the tube group is in contact with the solution tube 12. It is gradually cooled down and becomes a low-temperature gas 23.

By the way, the high temperature gas 22 flowing through the tube group end 30
is throttled and accelerated by the reduced gas flow path formed between the rectifier plate 14b and the solution tube 12, and the finned solution tube 13a with a large heat transfer area placed immediately after it is
, and only the finned solution tube 13a receives a heat load several times higher than the others. For this reason, the wall temperature of the finned solution tube 13a far exceeds 175° C., and local corrosion portions 24 occur in this portion. This high-temperature gas attack occurs not only in the solution tube 13a near the rectifier plate 14b but also in the solution tubes 12 and 13 near the rectifier plates 14a and 14c, but the extent of the attack is as follows.
The solution tube 13a is about twice as large as the others. This is because at the boundary where the smooth solution tube with low resistance changes to the finned solution tube with high resistance, the gas 23 exiting the smooth solution tube group suddenly experiences a large flow resistance when entering the finned solution tube group. The high-temperature gas 22 tries to flow more in the direction of the solid arrow A, which has less resistance than the dotted arrow B, and further flows along the end portion 30 of the tube group.
The liquid is also accelerated by the rectifying plate 14b, directly hits the finned solution tube 13a immediately after it, and attempts to flow in the direction of the tube group end 30, indicated by the solid line arrow C, where the resistance is lower than in the direction of the tube group center 31, indicated by the dotted line arrow D. Because it does.
Therefore, the local portion 24 of the finned solution tube 13a is attacked by the high temperature gas, causing corrosion.

In order to prevent such local corrosion, the present invention appropriately arranges the solution tubes and the rectifying plate, and
The high-temperature gas 22 is diluted with low-temperature gas from the central part 31 of the tube group to lower the temperature.

FIG. 5 shows a partial diagram of the solution tube group of the regenerator of the present invention. According to this figure, the last row of smooth solution tubes and the front row of finned solution tubes have a retractable structure. A space 40 is formed therein. With this configuration, the high temperature gas 22 throttled and accelerated by the current plate 14b is
Not only does it not directly hit the finned solution tube 13a immediately after, but also because there is a space 40, its flow resistance is rapidly reduced, and the low-temperature gas 23 from the center part 31 of the tube group is
It also promotes the flow to zero, where it is diluted and lowered in temperature. Microscopically, the low-temperature gas 23 that has flowed into the space 40 flows under the high-temperature gas 22 along the finned solution tube 13a and the finned solution tube 13 at the tube group end 30 that follows. This makes it difficult for the solution tube to come into contact with high-temperature gas. Therefore, space 4
By forming 0, it is possible not only to prevent high-temperature gas from attacking the finned solution tube 13a immediately after the rectifying plate 14b, but also to prevent high-temperature gas from coming into contact with the subsequent finned solution tube 13. has.

FIG. 6 shows a partial view of the solution tube group section of another regenerator of the present invention, in which the finned solution tubes 13a in the front row of the finned solution tube group arranged in a staggered pattern are shown.
was removed, and the rectifier plate 14b was attached to the lead-in portion of the smoothing solution tube 12 in the last row, but in this case as well, the same effect as in the case of FIG. 5 was obtained.

As described above, the direct-fired high-temperature regenerator of the present invention has the advantage that corrosion of the finned solution tubes at the end of the tube group can be prevented because the space is provided immediately after the high-temperature gas flow path narrowed by the rectifying plate and the smooth solution tube. has.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between the concentration and temperature of LiBr solution and the corrosion rate of metal, Fig. 2 is a vertical cross-sectional view of a conventional regenerator, Fig. 3 is a cross-sectional view taken along the - line in Fig. 2, and Fig. 4 is a graph showing the relationship between the concentration and temperature of LiBr solution and the corrosion rate of metal. This figure shows the gas flow state in the solution tube group section of a conventional regenerator, and FIGS. 5 and 6 are diagrams showing the gas flow state in the solution tube group section of the regenerator of the present invention. 1... Regenerator main body, 10... Burner, 11... Furnace cylinder,
12... Smooth solution tube, 13, 13a... Solution tube with fins, 14a, 14b, 14c... Straightening plate, 15... Chimney, 30... Tube group end, 31... Tube group center, 40...
space.

Claims (1)

[Scope of Claims] 1. In a direct-fired high-temperature regenerator consisting of a furnace cylinder section and a solution tube group section, a reduction plate formed between the solution tube and a rectifying plate provided at the end of the solution tube group section. A direct-fired high-temperature regenerator characterized by forming a space without placing a solution pipe immediately after a gas flow path. 2. The direct-fired high-temperature regenerator according to claim 1, wherein the rectifying plate is provided at a point where the extra-tube heat transfer area of the solution tube changes to become larger. 3. Claim 2 in which a rectifying plate is provided at the point where the solution tube changes from a smooth solution tube to a finned solution tube.
Direct-fired high-temperature regenerator described in section.