JPH0195290A - Heat exchanger - Google Patents

Abstract

PURPOSE:To alleviate the effect of dispersion of thermal stress as well as to enable heating to a heat transfer medium at a uniform temperature, by covering a heat pipe with a heat- insulating material, by positioning the evaporation part on the lower end of a heat pipe in a part confronting a heating source such as combustion gas, and by piercing a heat transfer pipe which flows the heat transfer medium through it through a condensation part on the upper end of a heat pipe. CONSTITUTION:The inlet side of a heat transfer medium is formed by inserting a heat transfer pipe 1 in a heat pipe 3 from the middle body of a pipe, piercing through its pipe wall. The heat transfer pipe 1 is a piping formed in a 'U' shape, extending in the direction to the top end of a condensation part 3b along the axis of a heat pipe 3, passing through the condensation part 3b, going outside piercing through the top end, forming an outlet side. A structure is such that the heat transfer pipe 1 is heated by the evaporating latent heat in the condensation part 3b of a heat pipe 3. The middle body of a heat pipe 3 is held by the wall of a furnace 5 by the intermediary of a heat-insulating material 6, so that the evaporation part 3a of a heat pipe 3 is projected to a heating source 8 in high temperature, from a through hole 9 provided on the wall of a furnace 5. The side of a condensation part 3b through which the heat transfer pipe 1 is pierced is projected to the outside of a combustion furnace. The exposed part is covered with a warmth-keeping material 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat exchange device that performs uniform heating using a heat pipe.

[Conventional technology]

Conventionally, heat exchangers with metal tubes as heat transfer walls have been widely used, and heat transfer is performed by sandwiching the heat transfer wall, which is a metal tube, and passing a heat transfer medium through the outside and inside of the wall. The heat transfer medium is heated or cooled by heat conduction through the walls.

Heat exchange at low temperatures in the humidity range of several tens to hundreds of degrees is performed by convective heat transfer of the heated fluid on the outside of the metal tube to the heat transfer medium inside the tube. This is a common tube plate heat exchanger. On the other hand, heat exchange in high temperature ranges, as seen in boilers, for example,
Heat is transferred to the heat transfer medium in the heat transfer tube by radiation such as flames caused by combustion of fuel and convective heat transfer of combustion gas, and it is necessary to plan with the balance of heating amount in consideration.

[Problem that the invention seeks to solve]

The problems will be explained below based on drawings of a conventional heat exchange device.

FIG. 3 is a partial sectional view schematically showing a multi-tubular heat exchange device, and numeral 10 is a combustion device. The combustion device 10 has a burner 12 disposed in the lower part of the interior, and burns supplied heavy oil etc. to form a combustion zone 11 consisting of combustion flame and combustion gas inside the device 10, and waste gas is transferred to the device 10. It is designed to be discharged from a flue 15 provided above. Side wall 16 of combustion zone 11 of combustion device IO
A plurality of heat transfer tubes 1 through which a heat transfer medium (refrigerant) flows in the direction of the arrow enter from above the combustion zone by penetrating the side wall from the outside, and extend vertically downward along the side wall. It is arranged so as to penetrate the side wall 16 from below the area and be connected to the outside.

In the high-temperature region heat exchange device configured in this way, the heat transfer tubes 1 are capable of transmitting combustion flame and radiation from the inner wall of the combustion device,
Since the combustion gas is heated by being exposed to convective heat transfer, planning the combustion conditions to maintain a constant temperature distribution within the combustion zone requires extremely complicated calculations, and the Yoshiba Plan Even if it were possible, it is actually extremely difficult to heat the heat exchanger tube to a uniform temperature. Therefore, due to non-uniform heat distribution and heat transfer, the elongation and bending of the heat exchanger tubes becomes uneven, which inevitably causes thermal stress problems.

In particular, the above-mentioned problem has a serious effect on the heat exchanger of a fuel reformer in a fuel cell plant, and is a manufacturing difficulty.

The present invention was made in view of the above problems, and aims to heat a heat transfer medium at a uniform temperature, reduce the influence of variations in thermal stress, and reduce complexity in design. It is.

[Means for solving problems]

The present invention aims to avoid uneven heating and unbalanced stress caused by direct contact of heat transfer tubes through which a heat transfer medium (refrigerant) flows with high-temperature parts such as combustion flames, combustion gas, or waste gas. , attempts to achieve the above object by interposing a heat pipe.

That is, the heat pipe is covered with a heat insulating material, the evaporating part at the lower end of the heat pipe is located in a part corresponding to the heat source such as combustion gas or high temperature gas, and heat is transferred to the condensing part at the upper end of the heat pipe. A heat exchange device was constructed by passing a heat transfer tube through which a medium flows.

[Effect]

In the present invention, heat is transferred between the high-temperature heat source and the heat transfer tube through the heat pipe, so that the heat transfer tube is no longer directly exposed to the high-temperature heat source, thereby eliminating the inconvenience caused by this. Ru.

In other words, the evaporation part of the heat pipe is arranged so as to protrude into the combustion zone of the combustion device or into the waste gas passage, and the working fluid in the heat pipe is evaporated by the heat of the high-temperature heat source, and the steam is generated in the heat pipe. Due to the pressure difference, the latent heat of vaporization is sent to the am section of the heat pipe and releases the latent heat of vaporization. Since a heat transfer tube through which a heat transfer medium (refrigerant) flows is inserted in the condensing portion of the heat pipe, the heat transfer medium (refrigerant) in the heat transfer tube is heated by the latent heat of vaporization. Therefore, the heat transfer tubes are always heated by the vapor of the working fluid at a uniform temperature, so the circulating heat transfer medium (refrigerant) is heated to a uniform temperature and uneven heat distribution is eliminated, thereby eliminating problems caused by this. The anxiety about it disappears.

The problem of temperature distribution in a high-temperature heat source is a problem related to heating of the evaporation section of a heat pipe, so some variation is allowed, so the difficulty in planning in that sense is alleviated.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a partial sectional view showing the structure of a first embodiment of the present invention, and FIG. 2 is a partial sectional view showing the structure of a second embodiment.

In FIG. 1, reference numeral 1 denotes a heat transfer tube, which is a U-shaped tube formed so that a heat transfer medium (refrigerant) flows as shown by the arrow. In other words, it penetrates the pipe wall from the intermediate body part of the heat pipe 3 and enters the inside thereof, forming the inflow side of the heat transfer medium, which forms the inflow side of the heat transfer medium.
A conduit formed in a U-shape so as to extend along the axis of the condensing part 3b toward the terminal end of the condensing part 3b, pass through the condensing part 3b, pass through the terminal end, go out to the outside, and form an outflow side. It is. Therefore, the heat exchanger tube 1 is the condensing section 3 of the heat pipe 3.
It is heated by the latent heat of vaporization at b.

The heat pipe 3 has an intermediate body portion held by the combustion device wall 5 via a heat insulating material 6 so that its evaporating portion 3a projects into the high-temperature heat source 8 from a through hole 9 provided in the combustion device wall 5. has been done. The condensing section 3b side in which the heat exchanger tube 1 is inserted is exposed to the outside of the combustion device. The exposed portion is covered with a heat insulating material 7. Note that although the first embodiment shows only one heat exchanger tube, it does not matter how many there are.

Next, as shown in FIG. 2, in the second embodiment, instead of the heat transfer tube of the above example, a jacket tube 2a that acts as a heat transfer tube and serves as an outflow path for the heat transfer medium, and a jacket tube 2a for the inflow of the heat transfer medium. A double-tube type bayonet tube 2 consisting of an outer jacket tube 2a and an inner jacket tube 2b inserted concentrically therein is used as a channel, and is inserted into the condensing part 3b of the heat pipe 3. Although it differs from the first embodiment in that it is different from the first embodiment, the operation and effect are the same.Although the catalyst layer 17 is shown between the outer jacket tube 2a and the inner jacket tube 2b in FIG. This is not just about heat transfer;
This shows that it can also be used in chemical reactions (endothermic reactions).

〔Effect of the invention〕

As described above, the present invention interposes a heat pipe between the high-temperature heat source and the heat transfer tube or bayonet tube to perform heat transfer, thereby eliminating the need for a conventional heating reaction tube, especially a catalyst etc. sealed inside. It was possible to make it suitable for a heat exchange device that requires a uniform heating heat transfer surface, such as a converter device. In other words, by interposing a heat pipe, it is easier to solve various problems caused by non-uniform heating temperature of heat transfer tubes through which a heat transfer medium (refrigerant) flows. Taking advantage of the transfer characteristics, it is possible to easily overcome the difficult problem of uniformly heating the heat transfer medium by appropriately arranging the heat transfer tubes.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing the configuration of a first embodiment of the present invention;
FIG. 2 is a partial cross-sectional view showing the configuration of a second embodiment, and FIG. 3 is a partial cross-sectional view schematically showing a conventional multi-tubular heat exchanger. 1: heat transfer tube, 2: bayonet tube, 3: heat pipe, 3
a=evaporation section, 3b: condensation section, lO: combustion device, 11: combustion zone.

Claims (1)

[Claims] 1) A heat pipe with a working fluid sealed inside and arranged vertically is covered with a heat insulating material, and the heat pipe is placed at the lower end of the evaporation part of the heat pipe in the part corresponding to the heating source such as combustion gas or high temperature waste gas. A heat transfer tube through which a heat transfer medium flows is passed through the condensation section on the upper end side of the heat pipe, and at this time, the working fluid is evaporated within the heat pipe to maintain a uniform temperature in the longitudinal direction of the heat transfer tube. A heat exchange device characterized by: