JPH0771886A - Heat exchanger - Google Patents

Abstract

(57) [Abstract] [Purpose] In a heat exchanger having a group of cooling tubes for condensing and recovering or removing moisture in the inflowing gas,
(EN) Provided is a heat exchanger having a high heat exchange performance, which prevents deterioration of electric heat performance due to condensate inversion. [Constitution] In the present invention, a condensation recovery mechanism (11) for recovering the liquid (6) condensed in the lower part of the cooling pipe (4).
It is characterized in that the liquid (6) condensed in each cooling pipe is prevented from pouring down to the cooling pipe (4) below.

Description

Detailed Description of the Invention

[0001]

This invention relates to heat exchanger devices,
In particular, it relates to a heat exchanger used for the purpose of condensing and removing or recovering a moisture component contained in a gas.

[0002]

2. Description of the Related Art In a power plant or a chemical plant, in order to exhaust a high temperature gas containing a vapor component such as water vapor to the outside, the temperature of the exhaust gas is lowered and the moisture contained in the gas is condensed. Therefore, a condensation heat exchanger for removal or recovery may be installed. As an example, the basic configuration of this heat exchanger will be described with reference to FIG.

A gas inlet account 2 and a gas outlet account 3 are attached to both ends of the heat exchanger body 1, and a large number of cooling tubes 4 are provided inside the body 1 and between the inlet account 2 and the outlet account 3. A cooling pipe group 5 is provided. Further, a seat 7 for discharging the condensate 6 is provided below the heat exchanger body 1 closer to the gas outlet 3 than the cooling pipe group 5.

Exhaust gas 8 containing moisture at high temperature, that is, the gas to be cooled flows in from the deposit account 2 and flows through the cooling pipe group 5. Cooling water 9 having a temperature lower than that of the gas to be cooled 8 flows inside the cooling pipe 4, and the gas to be cooled 8 exchanges heat with the cooling water 9 to lower the temperature. At this time, if the temperature of the cooling pipe 4 is lower than the saturation temperature at the vapor partial pressure in the gas, that is, the dew point temperature, the vapor component in the gas 8 condenses on the surface of the cooling pipe and becomes liquid. This condensate 6 falls downward due to the action of gravity and reaches the lower floor of the heat exchanger body 1. The floor surface is slightly inclined, and the condensate 6 is discharged from the condensate discharge seat 7 to the outside of the heat exchanger. The cooled gas 10, which has been deprived of low temperature and moisture while flowing through the cooling pipe group 5, is exhausted from the gas outlet account 3.

[0005]

Needless to say, in such a heat exchanger, the quality of the heat transfer performance due to condensation affects the performance of the heat exchanger. If heat transfer performance can be improved, it will be possible to manufacture heat exchangers with the same amount of heat exchange in smaller dimensions, which will bring advantages such as reduction in manufacturing cost and space for installing heat exchangers. Efforts are being made. For example, in order to improve heat transfer performance, although not shown in FIG. 4, cooling fins for facilitating heat transfer are often attached to the cooling pipe 4. In this case, although it is possible to make the heat exchanger compact, there is a problem in that a large amount of cost is required to manufacture the cooling fins, which is not necessarily a cost reduction. Further, as a problem peculiar to the condensation heat transfer, there is a problem that the heat transfer is deteriorated due to the initialization. Inanitation is a phenomenon in which the condensate covers the cooling pipes, and heat transfer is significantly deteriorated. In condensing heat transfer, it is generally said that the thinner the liquid film on the cooling pipe, the better the heat transfer performance. However, in the case of the cooling pipe group configuration as shown in FIG. 4, the condensate condensed in the upper cooling pipe is dropped onto the lower cooling pipe in the process of dropping downward, so that the heat transfer performance in the lower cooling pipe is reduced. There is a problem of decrease. Although various studies have been conducted on the heat transfer reduction due to this inversion, according to Nusselt or Kern et al., The relationship between the number N of tube rows in the gravity direction and the heat transfer performance is given as shown in FIG. There is. (Reference: “Special Theory of Heat Transfer”, P133, edited by Yoshiro Katou et al., Yokendo, published in 1984. According to this, for example, when the number of tube rows is 10, heat transfer is caused by the influence of the localization. It is suggested that the performance deteriorates by about 30 to 45%. That is, it is apparent that the heat exchange performance can be improved if it is possible to prevent the inversion that occurs when the condensate pours into the cooling pipe group.

In view of these points, an object of the present invention is to provide a heat exchanger having improved heat exchange performance by suppressing performance deterioration due to the inversion of the condensate in the cooling pipe group.

[0007]

The present invention provides a heat exchanger in which a gas flowing into a predetermined space is cooled by a plurality of cooling pipes arranged in the space through which a refrigerant flows and the space is provided. A means for collecting condensed liquid that has been generated on the outer surfaces of the plurality of cooling pipes and drops below the pipes is provided at a predetermined interval between the plurality of cooling pipes in the direction of gravity.

[0008]

In the condensing heat exchanger of the present invention, a device for recovering the condensate is provided between the tube groups, so that it is possible to prevent a decrease in heat transfer due to the inversion of the condensate. Since heat exchange loss due to sensible heat exchange of liquid does not occur, high heat exchange performance can be exhibited.

[0009]

1 and 2 show an embodiment of the present invention.
FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG. 2 is a detailed view of a portion for discharging a condensate. For the parts not shown below, the numbers in the figures already explained are used.

On the upper part of the heat exchanger body 1, there is a gas deposit account 2,
A gas outlet 3 is attached to the lower part in the direction of gravity, and a cooling pipe group 5 composed of a large number of cooling pipes 4 provided inside the body 1 and between the inlet 2 and the outlet 3 is provided. The cooling pipes 4 constitute cooling pipe groups 5a to 5d every two rows, and a condensate separator 11 constituted by an L-shaped angle is provided immediately below the cooling pipe groups 5a. Further, two rows of cooling pipe groups 5b are provided below the same, and the same structure is repeated thereafter. FIG. 2 is a view showing a part of a cross section in the vertical direction of the paper surface of FIG. The condensate separator 11 is attached so as to be inclined in the longitudinal direction, and a hole 12 for taking out the condensate is formed in the inclined lower end. A condensate recovery pipe 13 is provided below the hole 12 so that the condensate 6 can be discharged from the condensate discharge seat 7 to the outside of the heat exchanger.

The exhaust gas 8 containing a high temperature and humidity, that is, the gas to be cooled flows in from the deposit account 2 and flows through the first cooling pipe group 5a. Cooling water 9 having a temperature lower than that of the cooled gas 8 flows inside the cooling pipe 4, and the cooled gas 8 is cooled by the cooling water 9.
Exchanges heat with the temperature drop. At this time, the temperature of the cooling pipe 4 is lower than the saturation temperature at the vapor partial pressure in the gas, that is, the dew point temperature.
When the temperature is low, the vapor component in the gas 8 condenses on the surface of the cooling pipe and becomes liquid. This condensate 6 falls downward by the action of gravity and is collected by the condensate separator 11. The condensate separator is inclined, and the condensate 6 drops downward from the hole 12 at the end of the separator 11 and is collected by the condensate recovery pipe 13 and discharged from the condensate discharge seat 7 to the outside of the heat exchanger. It The cooled gas reaches the lower part of the heat exchanger while repeating the same process, and the cooled gas 10 deprived of low temperature and moisture is exhausted from the gas outlet account 3. The condensate 6 that has dropped to the bottom of the heat exchanger flows down to the end on a sloped floor surface (not shown), and is discharged to the outside of the heat exchanger.

In the condensing heat exchanger of this embodiment, since a device for recovering the condensate is provided between the tube groups, it is possible to prevent the heat transfer from being lowered due to the inversion of the condensate. Moreover, since the temperature of the condensate is higher in the upper part where the vapor partial pressure is higher and lower in the lower part, there is no heat exchange loss due to sensible heat exchange between the lower cooling water and the condensate in the upper part.
It is possible to exhibit high heat exchange performance. Therefore, the heat exchange capacity equivalent to that of the conventional heat exchanger can be exhibited with a smaller number of cooling pipes, and the heat exchanger can be made compact, which in turn contributes to the compactification of the entire plant.

Another embodiment is shown in FIG. In this embodiment, C-type steel is used for the condensate separator for collecting the condensate. The operation and effect are similar to those of the embodiment shown in FIG. The case where the number of rows of the tube group is two is taken as an example. However, the effect of the present invention does not change even if the number of rows is one row or the performance is slightly lowered. Further, the present invention can be applied as it is even when the cooling fin is attached to the cooling pipe, and in this case, higher heat transfer performance can be exhibited.

[0014]

As described above, in the heat exchanger according to the present invention, the device for recovering the condensed water is provided between the pipe groups, so that the heat transfer is prevented from being lowered due to the condensation water inanization. It is also possible to achieve high heat exchange performance because heat exchange loss due to sensible heat exchange of condensed water does not occur. Therefore, the same heat exchange capacity as the conventional heat exchanger can be exhibited with a smaller number of cooling tubes,
It is possible to contribute to the compactification of the heat exchanger and the overall compactness of the plant.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a heat exchanger of the present invention.

FIG. 2 is a diagram showing details of a condensate discharge part of an embodiment of the heat exchanger of the present invention.

FIG. 3 is a diagram showing another embodiment of the heat exchanger of the present invention.

FIG. 4 is a block diagram of a conventional device

FIG. 5 is a diagram showing the action of inversion in condensation heat transfer.

[Explanation of symbols]

 1 ... Heat exchanger body 2 ... Gas inlet account 3 ... Gas outlet account 4 ... Cooling pipe 5 ... Cooling pipe group 6 ... Condensate 7 ... Condensate discharge seat 8 ... Cooled gas (high temperature / humidity) 9 ... Cooling water 10 … Cooled gas (low temperature / drying) 11… Condensate separator 12… Condensate outlet 13… Condensate recovery pipe

Claims (1)

[Claims] 1. A heat exchanger for cooling a gas flowing into a predetermined space by a plurality of cooling pipes in which a refrigerant arranged in the space flows and is provided horizontally, wherein the plurality of cooling units are arranged in the space gravity direction. A heat exchanger comprising means for collecting condensed liquid that is generated on the outer surfaces of the plurality of cooling pipes and drops below the pipes at predetermined intervals between the pipes.