JPH0241503Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat exchanger, and particularly to a vertical heat exchanger installed to preheat combustion air, etc. with exhaust gas.

[Conventional technology]

For example, as shown in FIGS. 3 and 4, in a combustion air preheating facility that uses exhaust gas from a radiant tube 32 of an annealing furnace 31 to preheat combustion air, individual heat exchangers 33, Partial heat exchanger 3
4 and a collective heat exchanger (not shown) to allow heat recovery. That is, the combustion air that has been preheated from the air supply pipe 36 through the heat exchangers 33 and 34 is supplied to the burner 35, where it burns fuel and flows through the radiation pipe 3.
2, the radiant tube 32 is heated to a high temperature, and the radiant heat heats the inside of the annealing furnace 31, and the exhaust gas exiting the radiant tube 32 is passed through the individual heat exchanger 33,
Passing through the partial heat exchanger 34, the exhaust gas outlet main 3
7 to the collective heat exchanger.

An example of a heat exchanger that can constitute the partial heat exchanger 34 as described above is the one described in Japanese Utility Model Application Publication No. 54-60351. The heat exchanger covers both end surfaces of a vertical cylindrical body with an upper end plate and a lower end plate, respectively, and forms a heat exchange chamber between the both end plates. A plurality of hollow heat transfer tubes are installed vertically to flow the heated air through the heat exchange chamber, while air flows into the upper side of the heat exchange chamber in order to flow the heated air from the top to the bottom in the heat exchange chamber. The tube is connected to the bottom side, and the air outflow tube is connected to the bottom side. In addition, in order to absorb thermal expansion and contraction of the cylindrical body when high-temperature gas flows in this heat exchange chamber, the lower end plate is connected to the lower side of the cylindrical body via an expansion tube such as a bellows, and In order to absorb the difference in the amount of thermal expansion and contraction between the cylindrical body and the heat transfer tube, the lower end side of each heat transfer tube is attached to the lower end plate with an expandable tube section interposed therebetween.

However, in the configuration in which each heat transfer tube is provided with an expandable tube section as described above, the manufacturing cost is extremely high, the manufacturing period is long, and maintenance is poor and repair is difficult. The problem arises.

Therefore, instead of having a structure in which a telescoping tube section is provided for each heat transfer tube, a telescoping tube section is inserted in the cylindrical body, thereby absorbing the difference in the amount of thermal expansion and contraction between the cylindrical body and the heat transfer tube. A structure is also adopted, and an example thereof will be explained with reference to FIG.

In FIG. 5, the lower part of the vertical cylindrical body 41 is partitioned by a lower tube plate 42 to form an exhaust gas inlet chamber 43, to which an exhaust gas inlet pipe 45 having a telescopic tube section 44 is connected. A plurality of heat transfer tubes 47 through which exhaust gas passes are disposed between the lower tube plate 42 and an upper tube plate 46 disposed above the lower tube plate 42, and an air inlet tube 48 and an air outlet tube 49 are arranged at the upper and lower ends. A heat exchange chamber 50 is formed connected to the upper tube plate 46, and an exhaust gas outflow chamber 51 is formed on the upper tube plate 46. This heat exchanger 40 is supported by a flange 52 provided at the upper end of the cylindrical body 41. Expandable pipe parts 53 and 54 are provided in the middle part of the heat exchange chamber 50 and the upper part of the exhaust gas inflow chamber 43, and the thermal expansion and contraction of the cylindrical body 41 that occurs when high temperature exhaust gas flows is transferred to the exhaust gas inflow chamber 43. The upper expandable tube section 54 absorbs the difference in thermal expansion and contraction between the cylindrical body 41 and the heat transfer tube 47.
It is designed to be absorbed by

[The problem that the idea aims to solve]

However, the heat exchanger 40 having the structure shown in FIG. 5 has a problem in that the expandable tube sections 44 and 54 provided on the exhaust gas inlet chamber 43 side are easily damaged. That is, in the vicinity of the exhaust gas inflow chamber 43, the exhaust gas, which is in a high temperature state before heat exchange with the heated air, comes into direct contact with the exhaust gas, so that these telescopic tube portions 44, 54 are also in a high temperature state. Because the expansion and contraction operations are repeated under such a state of large thermal load, that is, with reduced strength, damage such as cracks is likely to occur.

In particular, in the above conventional configuration, the telescopic tube portion 4
Among the parts 4 and 54, the telescopic pipe part 45 interposed in the exhaust gas inlet pipe 45 is more likely to be damaged. This is because the cylindrical body 41 is supported and fixed at the upper part, so thermal expansion that extends downward occurs throughout the body, and the expandable tube section 54 is provided to absorb this expansion deformation. This is because the exhaust gas inflow chamber 43 on the lower side of the expandable tube section 54 is not fixed, so that the expandable tube section 54 hardly absorbs thermal expansion. As a result, the exhaust gas inlet chamber 43 is displaced downward, thereby applying bending stress to the expandable tube portion 44 of the exhaust gas inlet pipe 45. In this way, the combined bending stress acts on the telescopic tube section 44, making it particularly susceptible to damage.

This invention was made in view of the above, and
The purpose is to provide a heat exchanger that can suppress damage to the expandable tube section inserted to absorb thermal expansion and contraction, and thereby extend its life.

[Means to solve the problem]

Therefore, in the heat exchanger of the present invention, the inside of the substantially vertical cylindrical body is divided into a lower tube sheet and an upper tube sheet, an exhaust gas inflow chamber is formed under the lower tube sheet, and a lower tube sheet and an upper tube sheet are formed. A heat exchange chamber is formed in between, and an exhaust gas outflow chamber is formed above the upper tube plate, and a plurality of hollow heat transfer tubes are provided for flowing the exhaust gas from the exhaust gas inflow chamber to the exhaust gas outflow chamber through the heat exchange chamber. An air inlet pipe is connected vertically between the two tube plates, and an air inlet pipe is connected to the upper side of the cylindrical body surrounding the heat exchange chamber, and an air outlet pipe is connected to the lower side of the part surrounding the heat exchange chamber. A fixing portion is provided at a portion surrounding the inflow chamber, and a telescopic tube portion is interposed in the cylindrical body between the upper tube sheet and the lower tube sheet and above the upper tube sheet. It is characterized by

[Effect]

According to the above configuration, the thermal expansion and contraction of the entire heat exchanger is absorbed by the expansion tube section (hereinafter referred to as the first expansion tube section) located above the upper tube sheet, and the cylindrical body and the heat transfer tube The difference in thermal expansion and contraction between the lower tube sheet and the upper tube section is absorbed by the expansion tube section (hereinafter referred to as the second expansion tube section), but these first and second expansion tube sections absorb the thermal load. located in a small area. In other words, in the horizontal cross-section, the temperature distribution inside the heat exchange chamber is high on the inner side near the heat transfer tube through which the exhaust gas flows, and low on the cylindrical body side surrounding the heat exchange chamber; In this case, the exhaust gas inlet chamber side is higher and the exhaust gas outlet chamber side is lower along the exhaust gas flow direction. Furthermore, in the above, since the heated air flows into the heat exchange chamber from the exhaust gas outflow side,
The temperature on the exhaust gas outflow side is lower. The above-mentioned first and second expandable pipe parts are provided along the cylindrical body which is in the lowest temperature state in the horizontal cross-sectional direction, and also in the vertical direction at a position on the exhaust gas inflow chamber side where the temperature is high. Rather, in particular, the first telescopic pipe section is provided on the side of the exhaust gas outflow chamber where the temperature is the lowest. In this way, each expandable tube section is provided in a region with a lower temperature,
Since thermal expansion and contraction is absorbed while suppressing a decrease in strength due to temperature rise, damage such as cracks is less likely to occur, thereby extending the service life.

In addition, in the above, since the entire heat exchanger is supported and fixed by the fixed part on the outer surface of the exhaust gas inflow chamber, almost no displacement occurs in this area during thermal expansion and contraction. As in the example above, even when an exhaust gas inlet pipe with a telescoping pipe section is connected from the side, no bending stress acts on the telescoping pipe section of the exhaust gas inlet pipe. Only simple tensile compression in the axial direction due to thermal expansion acts. In this way, also for the exhaust gas inlet pipe connected to the exhaust gas inlet chamber,
A connection structure that is less likely to cause damage can be achieved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, the lower part of a vertical cylindrical body 1 is partitioned by a lower tube plate 2 to form an exhaust gas inflow chamber 3,
An exhaust gas inlet pipe 5 with a telescopic pipe section 4 is connected. A heat exchange chamber 10 is formed between the lower tube sheet 2 and the upper tube sheet 6 disposed above it, and a plurality of heat transfer tubes 7 (only one is shown in the figure) through which exhaust gas passes are arranged. At the same time, both ends thereof penetrate the lower tube sheet 2 and the upper tube sheet 6 and are welded and fixed. Further, an air inlet pipe 8 and an air outlet pipe 9 are connected to the upper and lower ends of the heat exchange chamber 10, and a jamb plate 11 is disposed between these to form a meandering air passage. . An exhaust gas outflow chamber 13 is formed on the upper tube plate 6, and a flange 12 is provided on the outer periphery of the upper end thereof. A fixing part 16 is provided on the outer surface of the exhaust gas inflow chamber 3, and the fixing part 16 and the flange 12 are configured to support the entire heat exchanger 20. On the other hand, telescopic tube sections 14 and 15 are provided in the intermediate portion of the heat exchange chamber 10 and on the outer surface of the exhaust gas outflow chamber 13 above the upper tube plate 6.

In addition, at the welded attachment part between the lower end of the heat transfer tube 7 and the lower tube plate 2, the amount of protrusion of the heat transfer tube 7 from the lower tube plate 2 is h, as shown in FIG. The distance between the centers of the heat transfer tubes 7 (arrangement pitch) is p, the outer diameter of the heat transfer tubes 7 is d, the protrusion angle θ of the heat transfer tubes 7 is defined as tanθ=h/(p-d), and this tanθ but
It is set to be in the range of 0.291 to 0.971.

According to the above configuration, the entire heat exchanger 20 is supported and fixed by the fixing part 16 on the outer surface of the exhaust gas inflow chamber 3, so that it does not expand downward during thermal expansion and contraction, and therefore the exhaust gas, which has the highest temperature and large thermal load, A simple tensile compression acts on the expandable tube portion 4 of the inlet pipe 5, and no combined external force of bending and tensile compression acts on it, making it less likely to be damaged. Note that stress is absorbed by the thermal expansion and contraction of the entire heat exchanger 20 by simple tension-compression deformation of the expansion tube section 15 provided in the exhaust gas outflow chamber 13, and the stress is absorbed by the thermal expansion and contraction of the entire heat exchanger 20. The difference in thermal expansion/contraction with 7 is absorbed by the expansion/contraction tube section 14. Furthermore, since these expandable tube sections 14 and 15 are arranged near the air inlet tube 8, which has a small thermal load, their lifespan is significantly extended.

On the other hand, in the conventional heat exchanger 40 described based on FIG. 5, there has been a problem in that the exhaust gas inlet chamber 43 suffers from melting due to afterburning. This is because the protrusion amount h of the heat transfer tubes 47 at the attachment point between the lower tube plate 42 and the heat transfer tubes 47 is approximately 20 mm, and the heat transfer tubes 47 are arranged closely, resulting in poor workability during welding. Welding between the two becomes incomplete due to defects such as poor penetration. Therefore, it is easily damaged when subjected to heat load, and when it is damaged, the combustion air in the heat exchange chamber 50 flows into the exhaust gas inflow chamber 43, reducing the amount of air supplied to the burner 35, which causes incomplete combustion. It was considered that this was caused by unburned gas entering the exhaust gas inlet chamber 43 and being combusted by the air leaking there.

Therefore, in the heat exchanger 20 in the above embodiment, the protrusion amount h of the heat transfer tube 7 is set as described above at the attachment welding part between the lower tube plate 2 and the heat transfer tube 7, and thereby, the The workability of welding has been improved, and as a result, the penetration of the fillet, the uniformity of both leg lengths, and the internal quality of the weld are good, resulting in a perfect weld, and there is no risk of breakage even under heat load. As a result, the above-mentioned afterburning does not occur, so the life of the entire heat exchanger is improved.

To give a specific example, the heat transfer tube 7 has an outer diameter of
21.7mm, material is SUS-304, number of tubes is 45,
The heat transfer area is 2.2 m ² , the lower tube plate 2 has a plate thickness of 6 mm, the material is SUS-309, the tube protrusion h is 5 mm (tan θ = 0.485), and the cylindrical body 1 is as follows:
The outer diameter is 250 mm, and the scheduler is 5. The upper part is made of SUS-304 and the lower part is SUS-309. The upper telescopic tube part 15 is made of SUS-304 and has a plate thickness of 0.6.
mm, double welded type, middle expandable tube part 14,
The heat exchanger 20 was made of SUS-316, plate thickness 0.6 mm, and double welded. When this was applied to the partial heat exchanger 34, which has been prone to melting accidents than before, it was found that melting occurred. There were no accidents.

Incidentally, the heat exchanger of the present invention has the above-mentioned individual heat exchanger 3.
Partial heat exchanger 3 of heat recovery equipment that recovers heat in three stages: 3, partial heat exchanger 34, and collective heat exchanger
The present invention is not limited to the one applied to 4, but can also be applied to various heat exchangers such as a heat exchanger that recovers heat in one stage.

[Effect of idea]

As described above, in the heat exchanger of the present invention, the inside of the substantially vertical cylindrical body is divided into a lower tube sheet and an upper tube sheet, an exhaust gas inflow chamber is formed under the lower tube sheet, and an exhaust gas inflow chamber is formed under the lower tube sheet. A heat exchange chamber is formed between the tube sheet and an exhaust gas outflow chamber is formed above the upper tube sheet, and a plurality of hollow conductors are formed for flowing exhaust gas from the exhaust gas inflow chamber to the exhaust gas outflow chamber through the heat exchange chamber. A thermal tube is installed vertically between both tube sheets, and an air inlet pipe is connected to the upper side of a portion of the cylindrical body surrounding the heat exchange chamber, and an air outlet pipe is connected to the lower side of the portion surrounding the heat exchange chamber, and further,
A fixing portion is provided at a portion of the cylindrical body that surrounds the exhaust gas inflow chamber, and the cylindrical body includes:
It has a configuration in which telescopic tube sections are interposed between the upper tube sheet and the lower tube sheet and above the upper tube sheet.

As a result, the expansion tube section, which absorbs the thermal expansion and contraction of the entire cylindrical body and the thermal expansion and contraction of the cylindrical body and the heat transfer tube, is placed in an area with a small thermal load, so the strength decreases as the temperature rises. Thermal expansion and contraction is absorbed in a state where deterioration is suppressed, and as a result, damage such as cracks is less likely to occur. In addition, since the entire heat exchanger is supported and fixed by the fixed part on the outer surface of the exhaust gas inflow chamber, almost no displacement occurs in this area during thermal expansion and contraction. Even when an exhaust gas inlet pipe with a telescoping pipe section is connected from the side, no bending stress acts on the telescoping pipe section of the exhaust gas inlet pipe, and simple tension in the axial direction Since only compression is applied, damage to the expandable tube section at this location is also suppressed. In this way, damage to each expandable tube section is suppressed, resulting in an effect that the service life can be extended.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of one embodiment of the present invention;
The figure is an enlarged sectional view of the main part, FIGS. 3 and 4 are a front view and a partially sectional side view showing the arrangement of a heat exchanger in an annealing furnace, and FIG. 5 is a longitudinal sectional front view of a conventional example. 1 is a cylindrical body, 2 is a lower tube plate, 3 is an exhaust gas inlet chamber, 4, 14, 15 are telescopic tube sections, 5 is an exhaust gas inlet pipe, 6 is an upper tube plate, 7 is a heat transfer tube, 8 is an air inlet pipe, 9 is an air outlet pipe, 10 is a heat exchange chamber, 13
2 is an exhaust gas outflow chamber, and 20 is a heat exchanger.

Claims (1)

[Scope of utility model registration request] The inside of the almost vertical cylindrical body is divided into a lower tube sheet and an upper tube sheet, with an exhaust gas inflow chamber below the lower tube sheet, a heat exchange chamber between the lower tube sheet and the upper tube sheet, and an upper tube sheet. An exhaust gas outflow chamber is formed on the upper side of each, and
A plurality of hollow heat transfer tubes for flowing exhaust gas from the exhaust gas inflow chamber to the exhaust gas outflow chamber through the heat exchange chamber are installed vertically between both tube plates, and a portion of the cylindrical body surrounding the heat exchange chamber is An air inlet pipe is connected to the upper side and an air outlet pipe is connected to the lower side.Furthermore, a fixing part is provided at a portion of the cylindrical body surrounding the exhaust gas inflow chamber, and the cylindrical body is connected to the upper pipe. A heat exchanger characterized in that telescopic tube sections are interposed between the plate and the lower tube sheet and above the upper tube sheet.