JP2012097991A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger having durability and excellent heat resistance and corrosion resistance in a combustion exhaust gas flow path for waste or the like, and capable of performing heat exchange with high efficiency.SOLUTION: The heat exchanger 1 includes a heat transfer tube 2 whose rear end is open and front end is composed of closed ceramic, and a metal inner tube 3 arranged to an inner wall of the heat transfer tube via a predetermined gap and communicated with the gap, and is configured such that the front end of the heat transfer tube is arranged in the combustion exhaust gas flow path while being tilted to a downstream side of combustion exhaust gas, and liquid introduced inside the heat transfer tube from the rear end of the heat transfer tube reaches to the front end of the heat transfer tube through a gap between the inner wall of the heat transfer tube 2 and the metal inner tube 3, flows into the inside of the metal inner tube 3 at the front end, and is derived to the outside from another end of the metal inner tube 3.

Description

  The present invention relates to a heat exchanger, for example, a heat exchanger that is installed in a combustion exhaust gas passage such as an incinerator that incinerates waste and performs heat exchange with the combustion exhaust gas.

  In incinerators that incinerate industrial waste, etc., the thermal energy of combustion exhaust gas generated by incineration is recovered by exchanging heat with a low-temperature gas or liquid, and the recovered energy is effectively used. .

As this type of heat exchanger, for example, a heat exchanger disclosed in Patent Document 1 has been proposed. This heat exchanger will be described with reference to FIG.
As shown in FIG. 6, the heat exchanger 30 includes a ceramic heat transfer tube 31 and a metal inner tube 32 disposed inside the heat transfer tube 31 with a predetermined gap from an inner wall of the heat transfer tube 31. ing. A gas pipe 33 is connected to the heat transfer pipe 31, and a gas pipe 34 is connected to the metal inner pipe 32.

The heat transfer tube 31 is integrally formed by connecting an upper heat transfer tube 31a and a lower heat transfer tube 31b with a coupling 31c of a non-metallic refractory material. A flange 31d is formed at the upper end of the heat transfer tube 31.
The flange 31d is engaged with and suspended from the upper wall 40a of the flue gas passage 40 extending in the horizontal direction, so that the heat transfer tube 31 (heat exchanger 30) is attached to the wall surface of the flue gas passage 40. Fixed.

When the combustion exhaust gas G flowing in the combustion exhaust gas flow path 40 hits the heat exchanger 30, heat exchange is performed between the low-temperature gas La supplied from the gas pipe 33 and the combustion exhaust gas G via the heat transfer pipe 31. Done.
The gas La reaches the tip of the heat transfer tube 31 through a gap between the inner wall of the heat transfer tube 31 and the metal inner tube 32 while heat exchange is performed. Thereafter, the gas Ha heated to a high temperature by heat exchange flows into the metal inner tube 32 at the tip of the heat transfer tube 31 and is led out from the gas pipe 34 to the outside.

  In this heat exchanger 30, since the heat transfer tube 31 in contact with the combustion exhaust gas G is made of ceramics, it has excellent corrosion resistance. In addition to NOx and SOx, chlorine, fluorine is contained in the combustion exhaust gas G. Also, when a highly corrosive gas such as sulfur or alkali element is contained, it can be suitably used.

JP 2006-162103 A

  By the way, the above-mentioned heat exchanger performs heat exchange between combustion exhaust gas and gas, and has a problem that heat exchange cannot be performed with high efficiency. That is, the present inventor is a heat exchanger that performs heat exchange between a combustion gas and a liquid such as water in order to perform heat exchange with high efficiency, and in addition, a combustion such as an incinerator that incinerates waste or the like. The present inventors have come up with the present invention by intensively studying heat exchangers that can be suitably used in exhaust gas passages.

  An object of the present invention is to provide a heat exchanger that is excellent in heat resistance and corrosion resistance in a combustion exhaust gas passage such as an incinerator for incinerating wastes and the like, is durable, and can perform heat exchange with high efficiency.

  In order to achieve the above object, a heat exchanger according to the present invention is installed in a wall of a combustion exhaust gas passage that extends in the vertical direction and is configured such that the combustion exhaust gas flows vertically downward from above. The heat exchanger is disposed through a predetermined gap with respect to the heat transfer tube made of ceramics whose rear end portion is open and the front end portion is closed, and the inner wall of the heat transfer tube, A metal inner pipe communicating with the gap, the tip of the heat transfer tube is disposed in the combustion exhaust gas flow path so as to be inclined to the downstream side of the combustion exhaust gas, and from the rear end of the heat transfer tube to the inside of the heat transfer tube The liquid introduced into the heat transfer tube reaches the tip of the heat transfer tube through the gap between the inner wall of the heat transfer tube and the metal inner tube, flows into the metal inner tube at the tip, and flows from the other end of the metal inner tube to the outside. It is characterized by being configured to derive.

In this way, by arranging the heat transfer tube in a state where the heat transfer tube is tilted to the downstream side of the combustion exhaust gas, the heat transfer tube is compared with the vertical or horizontal flow of the combustion exhaust gas as shown in the conventional example. As a result, the heat transfer coefficient is increased and heat exchange can be performed with high efficiency.
In particular, the liquid that has flowed into the heat transfer tube boils in the gap between the inner wall of the heat transfer tube and the metal inner tube, and bubbles generated by the boiling move to the open end side (rear end side) of the heat transfer tube, thereby opening the heat transfer tube. The liquid which collides with the liquid supplied from the end side and is stirred and finally becomes high temperature flows into the inner metal tube at the tip of the heat transfer tube, and flows out from the other end of the inner metal tube to the outside. Therefore, sufficient heat exchange is performed.
Further, even when condensation occurs on the outer surface of the heat transfer tube, water droplets containing components such as sulfuric acid and nitric acid due to the condensation do not flow to the wall side (inner surface side) of the combustion exhaust gas channel. Corrosion of a member or the like for attaching the heat pipe can be suppressed.

  Here, a through hole is formed in the wall of the flue gas flow path in parallel with a perpendicular to the wall, and the through hole is formed in a shape bent at a position corresponding to the inner wall surface of the flue gas flow path. It is desirable to install a heat pipe.

In addition, a through hole inclined at a predetermined angle may be formed on the wall of the flue gas flow channel on the downstream side of the flue gas flow channel from a perpendicular to the wall, and a linear heat transfer tube may be installed in the through hole. desirable.
Furthermore, it is desirable that the heat transfer tubes are alternately arranged in the height direction so as to face the wall of the combustion exhaust gas flow path.

  According to the present invention, it is possible to obtain a heat exchanger that is excellent in heat resistance and corrosion resistance in a combustion exhaust gas passage such as an incinerator that incinerates waste, has durability, and can perform heat exchange with high efficiency.

It is sectional drawing which shows the heat exchanger concerning one Embodiment of this invention. It is sectional drawing which shows one heat exchanger shown by FIG. It is a principal part enlarged view of the heat exchanger shown by FIG. It is II sectional drawing of FIG. It is sectional drawing which shows the modification of the heat exchanger concerning this invention. It is sectional drawing which shows the conventional heat exchanger.

Hereinafter, an embodiment according to a heat exchanger of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the heat exchanger 1 is installed on a wall 10a of a flue gas passage 10 between an incinerator 30 or a melting furnace 30 and a purification device 20 such as a desulfurization or denitration device.
The flue gas flow path 10 in which the heat exchanger 1 is installed is extended in the vertical direction so that the flue gas G flows down vertically from the upper side of the flue gas flow path 10 toward the purification device 20 located below. It is configured.
As shown in FIG. 2, in the heat exchanger 1, the inner wall surface side of the wall 10a of the flue gas passage 10 is fixed by an irregular refractory 11, and the outer wall surface side of the wall 10a is fixed by a fixing member 12 (for example, rubber or the like). The elastic body is fixed. By fixing with the fixing member 12, the stress concerning the heat exchanger tube 2 can be relieved and the heat exchanger tube 2 can be prevented from being damaged.

  The heat exchanger 1 includes a heat transfer tube 2 made of ceramics having a rear end opened and a front end closed, and an inner metal tube 3 inserted and arranged in the heat transfer tube 2. As shown in FIGS. 2 and 3, the metal inner tube 3 is arranged with a predetermined gap with respect to the inner wall of the heat transfer tube 2, and the gap and the inside of the metal inner tube 3 communicate with each other. .

The rear end portion of the heat transfer tubes 2, the flange 2a is formed as shown in FIGS. 2 and 3, the flange portion 2a, inlet 4a of the liquid L _L is formed is stainless or fluorine resin coating A stainless steel introduction plate 4 is attached.
Then, as shown in FIG. 4, the inner metal tube 3 is inserted through the central portion of the introduction plate 4, and the introduction port 4 a is formed as four through holes around the inner metal tube 3. ing. The number of the inlets 4a is not particularly limited and can be increased or decreased as necessary.

Further, as shown in FIGS. 2 and 3, a stainless steel or fluororesin-coated stainless steel storage portion 5 for storing the liquid L _L is formed outside the above. The reservoir 5, inlet tube 5a for introducing the liquid L _L in reservoir 5 is attached.
Thus, since the reservoir 5 for storing the liquid L _L outside the introducing plate 4 is formed, the liquid L _L which inlet tube 5a is introduced, introduction port introducing plate 4 through the reservoir 5 It is supplied into the heat transfer tube 2 from 4a. In addition, it is preferable from the standpoint of assembling the heat exchanger 1 that the storage part 5 and the introduction plate 4 are configured as one integral member.

  The liquid supplied into the heat transfer tube 2 can be water, industrial water, pure water, or the like. In particular, it is preferable to use pure water from the viewpoint of preventing the heat transfer tube 2 and the metal inner tube 3 from being blocked by deposits and deposits.

Reference numeral 6 in the figure denotes a seal member disposed between the flange 2a of the heat transfer tube 2 and the wall 10a of the combustion exhaust gas passage 10, and a material such as rubber is used. The seal member 6 is used to prevent combustion exhaust gas from leaking from the furnace wall 10a and to fix the heat transfer tube 2. It is preferable that the fixing member 12 and the sealing member 6 are integrally formed as one member in terms of assembling the heat exchanger 1.
2 and 3, reference numeral 13 denotes a bolt for attaching the heat transfer tube 2, the introduction plate 4, the storage portion 5, and the like to the wall 10 a of the combustion exhaust gas passage 10, and the introduction plate 4 and the receiving flange 14. The flange 2 a of the heat transfer tube 2 is fixed by the introduction plate 4 and the receiving flange 14. In the figure, reference numeral 15 denotes an O-ring.

Further, the configuration of the heat transfer tube 2 will be described in detail. The heat transfer tube 2 is formed as a straight tube (straight tube).
As shown in FIG. 2, a through hole 10c through which the heat transfer tube 2 is inserted into the wall 10a of the flue gas passage 10 is formed at an angle θh inclined from the perpendicular line Y to the wall 10a on the downstream side of the flue gas G. Further, the heat transfer tube 2 is attached between the outer surface 10d of the flue gas passage 10 and the flange 2a of the heat transfer tube 2 via a seal member 6 having an inclined surface inclined at a predetermined angle. The inner metal pipe 42 is also formed as a straight pipe (straight pipe).
Specifically, as shown in FIGS. 2 and 3, the heat transfer pipe 2 in the flue gas passage 10 is disposed at an angle θ on the downstream side of the flue gas G with respect to the vertical line Y of the wall 10 a of the flue gas passage 10. Arranged in a tilted state.

  When this angle is less than 20 degrees, the furnace length of the heat transfer tube 2 cannot be sufficiently secured, and heat exchange cannot be performed with high efficiency. Moreover, there is a possibility that the corrosive liquid condensed on the surface of the heat transfer tube 2 may come into contact with the combustion exhaust gas passage wall 10a by the flow of the combustion exhaust gas G. On the other hand, when this angle exceeds 65 degrees, the sealing performance between the heat transfer tube 2 and the seal member 6a may be deteriorated. Moreover, since the adjacent introduction plate 4, the storage part 5, the heat transfer tube 2 and the like are close to each other and the distance becomes narrow and a space for installation cannot be secured, or replacement work efficiency may be lowered, it is not preferable. Therefore, the angle θ is preferably in the range of 20 to 65 degrees.

  In this way, the heat transfer tube 2 is disposed in a state of being inclined to the downstream side of the combustion exhaust gas G, so that the heat transfer tube is more than the case where it is disposed perpendicular to the flow of the combustion exhaust gas G as shown in the conventional example. The contact area with the combustion exhaust gas G in 2 can be increased, and heat exchange can be performed with high efficiency.

Further, when the combustion exhaust gas G flowing through the combustion exhaust gas passage 10 comes into contact with the heat transfer tube 2, condensation including components such as sulfuric acid and nitric acid may occur. At this time, since the heat transfer tube 2 is disposed in a state of being inclined to the downstream side of the combustion exhaust gas G, water droplets containing components such as sulfuric acid and nitric acid flow down to the tip end side of the heat transfer tube 2.
In this way, water droplets containing components such as sulfuric acid and nitric acid due to the condensation do not flow to the inner surface 10b side of the flue gas passage 10, so the flue gas passage wall 10a, the indeterminate refractory 11, and the seal member 6 Corrosion such as can be suppressed. Further, the water droplets due to this condensation fall from the distal end side of the heat transfer tube 2 to the purification device 20 positioned downward and are processed.

Moreover, as shown in FIG. 1, the said heat exchanger tube 2 is alternately arrange | positioned in the height direction facing the wall of a combustion exhaust gas flow path. Specifically, three heat transfer tubes 2 are provided on the left and right, respectively, but the present invention is not limited to this, and by installing a large number of heat transfer tubes 2, high-efficiency heat exchange can be achieved.
Further, since the combustion exhaust gas G contains very strong corrosive substances such as chlorine, fluorine, sulfur and alkali elements in addition to NOx and SOx, the heat transfer tube 2 reacts with components of incineration ash. It is preferable to use ceramics such as silicon carbide, titanium carbide and zirconium carbide which are difficult to resist and have excellent corrosion resistance and heat resistance. In addition, these ceramics are excellent also in heat conductivity, and it becomes possible to improve a heat exchange rate.

  The length A of the heat transfer tube 2 is ½ to 3 of the diameter B of the flue gas passage 10 when the cross section of the flue gas passage 10 is circular as shown in FIGS. / 2 is preferred. The outer diameter D of the heat transfer tube 2 at this time can be appropriately selected depending on the flow rate of the heat medium, but is preferably φ40 to φ280 mm and a wall thickness of 5 to 15 mm.

  Moreover, the surface roughness Ra of the inner surface of the heat transfer tube is preferably 0.3 μm to 200 μm. More preferably, the surface roughness Ra is 50 μm to 100 μm. By setting it as the said range, the bubble of a moderate magnitude | size will generate | occur | produce in the nucleate boiling of a heat medium, and it can heat-exchange efficiently.

The inner metal pipe 3 is not exposed to highly corrosive gas, but it is preferable to use stainless steel, Ni-base alloy, etc., which are excellent in corrosion resistance and heat resistance.
The inner metal tube 3 is preferably shorter than the length of the heat transfer tube, and the gap S is preferably formed at the tip of the heat transfer tube 2 so as to have an inner diameter corresponding to 1/2 of the inner diameter d of the heat transfer tube 2. When the gap S between the inner surface of the tip of the heat transfer tube 2 and the tip of the metal inner tube 3 is less than ½ of the inner diameter d of the heat transfer tube 2, the internal pressure of the gap S increases and the inner diameter of the heat transfer tube 2 increases. If it is equal to or more than d, the heat medium (liquid) does not flow to the tip, which is not preferable.

Further, the inner cross-sectional area of the inner metal tube 3 is preferably formed to be 100% to 130% of the inner cross-sectional area of the heat transfer tube 2 (excluding the cross-sectional area of the inner metal tube 3).
When the inner cross-sectional area of the metal inner tube 3 is smaller than the inner cross-sectional area of the heat transfer tube 2, the internal pressure increases due to the volume expansion of the heated heat medium (liquid), and the flow rate of the heat medium decreases. Absent. On the other hand, when the inner cross-sectional area of the metal inner tube 3 is larger than 130% of the inner cross-sectional area of the heat transfer tube 2, the flow rate of the heat medium (liquid) flowing in the heat transfer tube 2 is reduced, and heat exchange is performed with high efficiency. It is not preferable because it cannot be done.

  Also, the outer peripheral surface roughness of the inner metal tube 5 is preferably smooth in order to reduce the pressure loss. It is preferable that Ra ≦ 1 μm in the longitudinal direction of the tube.

Next, the operation and action of the heat exchanger 1 according to the present invention will be described. First, the liquid L _L (for example, water) introduced from the liquid introduction pipe 5 a into the storage unit 5 is led out from the introduction port 4 a of the introduction plate 4 to the inside of the heat transfer pipe 2. The liquid reaches the tip of the heat transfer tube 2 through the gap between the inner wall of the _LL heat transfer tube 2 and the metal inner tube 3, flows into the metal inner tube 3 at the tip, and other than the metal inner tube 3. Outflow from the end.

At this time, the heat transfer tube 2 is heated by the combustion exhaust gas G flowing through the combustion exhaust gas flow path 10, and the liquid flowing into the heat transfer tube 2 becomes a high-temperature liquid L _H by heat exchange. It is led out from the other end of the tube 3 to the outside.

At this time, since the temperature of the combustion exhaust gas G is generally 100 to 300 ° C., the temperature of the heat transfer tube 2 is also heated to the temperature.
As a result, the liquid flowing into the heat transfer tube 2 boils in the gap between the inner wall of the heat transfer tube 2 and the metal inner tube 3. As shown in FIG. 2, the bubbles F generated by the boiling move to the opening end side of the heat transfer tube 2, collide with the liquid supplied from the opening end side of the heat transfer tube 2, and sufficient heat exchange is performed.
Then, finally the liquid L _H became hot flows into 3 inside the pipe metal at the tip of the heat transfer tube 2, it flows out from the other end of the metal inner tube 3.

  Next, the modification of the heat exchanger concerning this invention is shown in FIG. The heat exchanger 40 is not a linear shape like the heat transfer tube 2 in the above-described embodiment, but a bent tube formed in a bent shape at a position corresponding to the inner wall surface 10b of the combustion exhaust gas passage 10. It is characterized in that it is used. That is, as shown in FIG. 5, the heat transfer tube 41 is bent at a position on the inner surface 10b of the combustion exhaust gas passage wall 10a, and the tip of the heat transfer tube 2 is tilted to the downstream side of the combustion exhaust gas G. It is arranged to be in a state.

  Specifically, as shown in FIG. 5, the heat transfer pipe 41 in the flue gas passage 10 is tilted at an angle θ to the downstream side of the flue gas G with respect to the perpendicular Y of the wall 10 a of the flue gas passage 10. Placed in a state. Further, the inner metal pipe 42 is also bent at a position where the inner surface 10b of the flue gas passage wall 10a is located so that the tip of the inner metal pipe 42 is inclined to the downstream side of the flue gas G. Has been placed. In addition, since the bent heat transfer tube 41 is used, the seal member 43 can be a member having no inclined surface unlike the seal member 6 having the inclined surface.

1 Heat exchanger 2 Heat transfer tube
2a Flange
3 Metal inner pipe 4 Introduction plate 5 Storage section 6 Seal member 10 Combustion exhaust gas flow path 10a Wall 10b Inner surface 10c Through hole 10d Outer surface 20 Purification device 40 Heat exchanger 41 Heat transfer tube 42 Metal inner tube 43 Seal member θ Combustion exhaust gas flow Angle formed between the perpendicular to the wall of the road and the heat transfer tube θh Angle formed between the perpendicular to the wall of the flue gas flow path and the through hole that passes through the heat transfer tube

Claims (4)

A heat exchanger that is installed in a wall of a flue gas passage that extends vertically and is configured such that flue gas flows vertically downward from above,
The heat exchanger is disposed through a predetermined gap with respect to an inner wall of the heat transfer tube and a heat transfer tube made of ceramics having a rear end portion opened and a front end portion closed, and communicates with the gap. An inner metal pipe, and the tip of the heat transfer tube is disposed in the combustion exhaust gas passage so as to be inclined to the downstream side of the combustion exhaust gas,
The liquid introduced into the heat transfer tube from the rear end of the heat transfer tube reaches the tip of the heat transfer tube through the gap between the inner wall of the heat transfer tube and the metal inner tube, flows into the metal inner tube at the tip, A heat exchanger configured to be led out from the other end of the metal inner tube.   A through hole is formed in the wall of the flue gas passage in parallel with the perpendicular to the wall, and a heat transfer tube formed in a shape that bends at a position corresponding to the inner wall surface of the flue gas passage is installed in the through hole. The heat exchanger according to claim 1, wherein the heat exchanger is provided.   A through-hole inclined at a predetermined angle is formed on the wall of the flue gas passage from the perpendicular to the wall to the downstream side of the flue gas passage, and a linear heat transfer tube is installed in the through-hole. The heat exchanger according to claim 1.   The heat exchanger according to any one of claims 1 to 3, wherein the heat transfer tubes are alternately arranged in the height direction so as to face the wall of the combustion exhaust gas flow path.

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