JPS5924798B2 - Regenerative heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a regenerative heat exchanger that effectively uses fluctuating thermal energy.

BACKGROUND OF THE INVENTION As shown in FIGS. 1 and 2, many thermal energy discharged from industrial equipment such as garbage incinerators have temporal fluctuations in discharge heat amount and discharge temperature.

Therefore, in most cases, such fluctuating thermal energy is not used effectively.

That is, at present, since the steady operation of the device is considered as the first condition, it is used only at the minimum level shown by the broken line in FIGS. 1 and 2.

However, when the temperature level is below 300°C and the fluctuations in the amount of heat discharged are relatively small, a method of absorbing the fluctuations using a type of heat storage device called a steam accumulator is still used.

The purpose of the present invention is to solve such problems by using a vertical shell-and-tube heat exchanger, in which the shell part has a melting point in the middle of the temperature fluctuation range of the high-temperature heat transfer medium passing through the heat transfer tubes. This object is achieved by providing a regenerative heat exchanger having a structure in which a molten substance is enclosed and fins extending along the tube axis are attached inside the heat transfer tube,
As a result, even if the heat transfer medium has a fluctuation range, it can be easily averaged and the heat transfer medium can be made into a heat transfer medium with less temperature fluctuation.

An embodiment of the present invention will be described below in detail based on drawings showing the embodiment.

In FIG. 3, reference numeral 1 indicates a thermal energy discharge source such as a garbage incinerator, and here it is assumed that high-temperature gas 4 is used as a heat transfer medium.

2 is a device that utilizes thermal energy from the thermal energy exhaust source 1, such as a gas turbine or a steam turbine.

Reference numeral 3 denotes a regenerative heat exchanger that is interposed between the thermal energy exhaust source 1 and the thermal energy utilization device 2, and mainly utilizes the heat of fusion of inorganic substances, so that the temperature of the high-temperature gas 4 reaches the melting point A in Fig. 2.
During the above time period, the excess heat melts the substance, first as heat of fusion, and then the excess heat becomes the melted substance (liquid).
heat is stored as sensible heat.

Next, when the temperature of the high-temperature gas 4 decreases to below the melting point A,
Conversely, thermal energy is released from the heat storage material as sensible heat and solidification heat to the gas 4, which is the heat transfer medium, to prevent the gas 4 from becoming low temperature.

Therefore, by designing the regenerative heat exchanger 3 taking into consideration the balance between heat transfer rate, temperature level, and heat capacity, it is possible to effectively utilize fluctuating thermal energy.

4a and 4b show a vertical shell-and-tube type regenerative heat exchanger 5, which includes a body outer panel 6 and upper and lower partition walls 7, 8.
and a shell portion 10 in which a molten substance 9 such as chloride having a melting point in the middle of the temperature fluctuation range of the high-temperature gas is sealed; It is composed of a plurality of heat transfer tubes 12 which form a passage for the high temperature gas 11 and exchange heat between the high temperature gas 11 and the molten substance 90. A plurality of fins 13 are provided along the tube axis direction in order to increase the heat transfer area and improve the heat transfer effect.

The thickness and number of the fins 13 are not particularly limited.

Note that the shell portion 10 needs to have a sufficient volume in consideration of the volume change due to the solid-liquid phase change of the molten substance 9.

With such a configuration, when high-temperature gas 11 with a fluctuation range is supplied, during the time period when the temperature of high-temperature gas 11 is higher than the melting point of molten substance 9, an excessive amount of heat is generated while passing through heat exchanger tube 12. melts the substance 9 as heat of fusion, and excess heat is stored as sensible heat of the molten substance 9.

Next, during the time period when the temperature of the high-temperature gas 11 decreases to below the melting point, the previously stored thermal energy is conversely released to the gas 11 through the heat transfer tube 12, and the temperature of the discharged gas is approximately close to the melting point. is maintained.

In addition, when a conventional regenerative heat exchanger is horizontal, a dead space is created in the upper part of the shell part, and some of the heat transfer tubes do not work effectively, resulting in poor efficiency. Now this will be resolved.

When a garbage incinerator is considered as the thermal energy emission source 1, the temperature of the exhaust gas discharged from the incinerator fluctuates between 5000C and 10000C with a temperature cycle of 0.5 to 1 hour.

In such cases, sodium chloride (
By using NaC,g, melting point 8004°C), the exhaust gas temperature can be averaged to approximately 800°C.

As described above, according to the present invention, even if the heat transfer medium has a fluctuation range, it can be easily averaged and a heat transfer medium with less temperature fluctuation can be obtained.

Furthermore, since the shell-and-tube type heat exchanger is of a vertical type, problems such as parts of the heat exchanger tubes not working effectively, which occur in the case of a horizontal type, do not occur.

Moreover, since the fins extending along the tube axis are provided inside the heat transfer tube, the heat transfer area can be increased and the heat transfer effect can be improved.

[Brief explanation of drawings]

Figures 1 and 2 are exhaust heat quantity and exhaust temperature characteristic diagrams with fluctuation ranges, Figure 3 is a system diagram in which the present invention is used, and Figures 4 a and b are longitudinal sections showing one embodiment of the present invention. Sectional view and cross-sectional view, FIG. 5 is a cross-sectional view of the heat exchanger tube. 5...Shell and tube type regenerative heat exchanger, 9.
...Melting substance, 10...Shell portion, 12...Heat exchange tube, 13...Fin.

Claims (1)

[Claims] 1 The shell and tube type heat exchanger is of a vertical type, and a molten substance having a melting point in the middle of the temperature fluctuation range of the high temperature heat transfer medium passing through the heat transfer tube is sealed in the shell part, and the tube axis is inserted into the heat transfer tube. A regenerative heat exchanger characterized by having fins along the direction.