JP2020029963A - Heat exchanger, and resin applied to heat exchanger - Google Patents

Abstract

To provide a heat exchanger capable of exchanging heat with exhaust air including sulfide, and optimally removing the sulfide.SOLUTION: In a heat exchanger 1 including a conduction pipe 2 through which a first fluid passes, by making a second fluid as an exhaust gas from a boiler including sulfide pass the outside of the conduction pipe 2, heat exchange is performed between the second fluid and the first fluid passing through the conduction pipe 2, a catalyst such as carbon fiber reductively reacting with the sulfide included in the second fluid is disposed on the conduction pipe 2 or a fin 3 in a manner of crossing the conduction pipe 2. Then, in coating the conduction pipe 2 with the resin having the carbon fiber, the carbon fiber is projected by about 1-1,000 μm, and a temperature of the first fluid is set to be a temperature easy for initiating oxidation-reduction reaction as the catalyst of the carbon fiber.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat exchanger, and more particularly, to a heat exchanger capable of removing pollutants such as sulfide from a fluid passed through the heat exchanger.

  Conventionally, various devices have been proposed in which sulfide contained in fuel is removed with a catalyst.

  For example, Patent Document 1 listed below proposes a device in which a gas discharged from a boiler is brought into contact with a catalyst, which is activated carbon, and this gas can be removed by converting the gas into sulfuric acid.

JP 2004-337776 A

  However, when sulfide is converted to sulfuric acid using a catalyst, the activation of the reaction varies depending on the reaction temperature. For this reason, there has been a problem that the reaction does not occur simply by bringing the sulfide into contact with the catalyst, and the sulfide is released during standby.

  On the other hand, a heat exchanger used in a boiler or the like heats water or the like to be heated using heat of the boiler.

  In view of the above, the present invention has been made in view of the above-mentioned problem, and enables heat exchange using heat contained in exhaust gas and heat exchange capable of optimally removing sulfide contained in the exhaust gas. It is about a vessel.

  That is, in order to solve the above-described problems, the present invention includes a conducting pipe through which the first fluid passes, and by passing the second fluid outside the conducting pipe, the first fluid passes through the conducting pipe. In a heat exchanger that performs heat exchange, a catalyst that undergoes a reduction reaction with sulfides and nitrogen oxides contained in the second fluid is provided on a conduit or a fin provided to cross the conduit. is there.

  According to this structure, since the catalyst is applied to the conduit or the fin, the sulfide can be converted into sulfuric acid and removed through the catalyst. At this time, by changing the temperature of the first fluid flowing through the conduit, the temperature can be set to a temperature at which the catalyst is most likely to undergo an oxidation-reduction reaction.

  Further, in such an invention, the catalyst is provided on the surface of the conduit or the fin via a resin.

  According to this configuration, since the catalyst is applied to the conduit and the fin via the resin, corrosion of the metal due to the sulfide can be prevented.

  Further, when the catalyst is provided on the surface of the conduit or the fin via the resin, the catalyst is provided so as to be exposed from the resin.

  With this configuration, the catalyst can be brought into contact with the second fluid to convert sulfide into sulfuric acid and remove it.

  Needle-like particles are used as such a catalyst.

  According to this structure, the needle-like particles can be made to protrude from the resin, and heat can be exchanged with the conductive tube or the like.

  Then, needle-like carbon fibers are used as such a catalyst.

  When such a material is used, the efficiency of heat exchange can be increased by thermal conductivity.

  ADVANTAGE OF THE INVENTION According to this invention, the heat exchanger which is provided with the conduit | pipe through which a 1st fluid passes, and passes a 2nd fluid outside the said conduit | pipe, and heat-exchanges with the 1st fluid passed through the conduit | pipe In the above, a catalyst that undergoes a reduction reaction with sulfides and nitrogen oxides contained in the second fluid is provided on the conduit or a fin provided so as to intersect with the conduit. Can be changed to sulfuric acid and removed. At this time, by changing the temperature of the first fluid flowing through the conduit, the temperature can be set to a temperature at which the catalyst is most likely to undergo an oxidation-reduction reaction.

The figure which showed the heat exchanger which is one Embodiment in this invention. Diagram showing the state of heat exchange and oxidation-reduction reaction with the coating film in the same form The figure which shows the heat exchanger in other embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the heat exchanger 1 in this embodiment includes a conduction pipe 2 through which a first fluid passes, and allows a second fluid to flow through a gap between the conduction pipes 2. Thus, heat exchange can be performed between the second fluid and the first fluid. Characteristically, a resin containing a catalyst is applied to the conduit 2 and the like, whereby components causing pollution are removed from sulfides and nitrogen oxides contained in the second fluid by the action of the catalyst. It is made possible. In addition, when the pollutant is removed by the action of the catalyst in this manner, the effect differs depending on the temperature of the catalyst. Therefore, the temperature of the first fluid in the conduit 2 can be changed to reduce the temperature of the catalyst. Alternatively, the oxidation-reduction reaction can be promoted, and the corrosion of the conduit tube 2 and the fins 3 can be prevented by coating with a resin containing a catalyst. Hereinafter, the present embodiment will be described in detail.

  The conducting tube 2 in the heat exchanger 1 can be heated (or cooled) by passing a first fluid, such as a liquid or a gas, therein, and has good heat conductivity at the time of heat exchange and corrosion. A material that does not easily occur is used. As such a material, for example, a metal such as stainless steel or copper is used. In this embodiment, the conductive tube 2 is formed of a flat member, and functions as a fin 3 itself. However, as shown in FIG. 3, the conductive tube 2 having a circular cross section is provided. The first fluid may be alternately moved in both the left and right directions by meandering this. When the conductive tube 2 having such a circular cross section is used, thin metal fins 3 orthogonal to the conductive tube 2 are arranged in parallel in order to improve the heat exchange efficiency with the second fluid. It is preferable to increase the contact area with the second fluid.

The second fluid that is externally passed through the heat exchanger 1 may be, for example, combustion gas from a boiler, exhaust gas from an engine, or the like. However, the gas burning fossil fuels, would contain such sulphides and nitrogen oxides, which will be released into the atmosphere becomes like SO _x or NO _x. Further, even if the removal treatment is performed immediately before the gas is separately released in order to prevent the release of the pollutants to the atmosphere, the metal is corroded by the sulfide and the like, so that the fin 3 has a hole. May be vacant or a crack may occur in the conduit 2. On the other hand, it is also possible to provide a coating such as a resin on the conduit 2 or the like. However, if the coating is performed only with the resin in this manner, the thermal conductivity is deteriorated, and the heat exchange efficiency is reduced. . Therefore, in this embodiment, a resin containing a catalyst is thinly applied to the conducting pipe 2 and the fins 3 of the heat exchanger 1 to remove air pollutants by the catalyst and prevent corrosion of the heat exchanger 1. In addition, the temperature can be set to an optimum temperature at which the catalyst can operate.

  As such a catalyst, various catalysts are used.For example, vanadium oxide or carbon fiber can be used as a catalyst for removing sulfides with sulfuric acid. For example, vanadium, molybdenum, tungsten, carbon fiber, or the like can be used. In these catalysts, the redox reaction is promoted as the contact area with the second fluid increases. Therefore, this catalyst is made into a powder and mixed into a resin, and the resin is applied to the conduit tube 2 and the fins 3 for coating. At this time, the catalyst is exposed from the surface of the resin and is brought into contact with the second fluid. However, when such a catalyst powder is exposed, if the spherical powder is exposed, the contact with the second fluid is not efficiently performed, and the contact between the conduit 2 and the outside is not good. Heat exchange cannot be performed. Therefore, in this embodiment, needle-like powder of carbon fiber is used as the catalyst. As the acicular powder, a carbon fiber having an average length of about 1 μm to 1000 μm is used, and the carbon fiber is protruded from the surface of the resin so as to rise. Then, the base end side of the carbon fiber approaches the conducting tube 2 and the fins 3 and the like, and heat can be conducted from the exposed portion on the front end side to exchange heat with the outside.

  As such a resin, a thermosetting resin can be used, and for example, an epoxy resin, silicone, an unsaturated polyester resin, a vinyl ester resin, a benzoxazine resin, a phenol resin, a urea resin, a melamine resin, and a polyimide resin are used. . At this time, it is preferable to use a resin having high adhesiveness to the metal of the heat exchanger 1.

  When a catalyst particle such as carbon fiber is put into the resin, a dispersant is used. Various dispersants are used as the dispersant, for example, a polymer dispersant, a surfactant dispersant, an inorganic dispersant, and the like. Among them, when a polymer type dispersant is used, there is an advantage that an effective dispersing effect can be obtained with a small amount, and the dispersion can be maintained for a long time due to a repulsive effect due to steric hindrance of the dispersant molecule. On the other hand, when a surfactant type dispersant is used, there is a merit that it can be adsorbed on the particle surface of the carbon fiber to have a wetting action. Further, when an inorganic dispersant is used, there is an advantage that the adsorption to the particle surface in an aqueous system is strengthened and a stabilizing action by electrostatic repulsion can be obtained. Here, when a polymer type dispersant is used, as the anionic dispersant, a polycarboxylic acid type, a naphthalenesulfonic acid formalin condensation type, a polycarboxylic acid partial alkyl ester type, or the like can be used, and a nonionic type dispersant can be used. As the dispersant, a polyethylene glycol or polyether-based dispersant can be used, and as the cationic dispersant, a polyalkylene polyamine-based dispersant can be used. When a surfactant-type dispersant is used, an alkylsulfonic acid-based dispersant or the like can be used as an anionic dispersant, and an ammonium-based or alkylpolyamine-based dispersant can be used as a cationic dispersant. As the nonionic dispersant, dispersants such as higher alcohol alkylene oxides and polyhydric alcohol esters can be used. When an inorganic dispersant is used, a polyphosphate dispersant or the like can be used as an anionic dispersant.

  Then, the acicular powder or the dispersant of the carbon fiber is put into the resin and mixed with stirring to uniformly disperse the carbon fiber in the resin. At this time, the content of the carbon fiber is set to about 30% by weight to 80% by weight with respect to the resin.

  Next, a method and an operation when the resin having such a configuration is applied to the heat exchanger 1 will be described.

  First, when a resin is applied to the heat exchanger 1, the surface of the heat exchanger 1 is cleaned and dried, and then the resin is doped with carbon fiber dispersed resin. Further, when applying the resin to the heat exchanger 1 already installed at the site, the resin is applied to the conductive tube 2 and the fins 3 by a sprayer, a brush or the like. Then, drying is performed for a predetermined time to prevent dripping or the like. At this time, the coating thickness is set so that the carbon fibers can protrude from the surface, is set to about 100 μm to 500 μm, and the protrusion amount of the carbon fibers is set to about 1 μm to 1000 μm.

  Next, the operation when the heat exchanger 1 coated with the resin is used will be described.

First, when using the heat exchanger 1 with the exhaust gas from the boiler or the engine as the second fluid, the second fluid is passed between the conduits 2 and the first fluid for lowering the temperature of the second fluid. Pass through the conduit 2. Then, the first fluid passed through the inside of the conduit 2 exchanges heat with the outside by the acicular powder in the resin applied to the surface of the conduit 2, and passes through at a low temperature from the upstream side. Then, the downstream side becomes higher in temperature due to heat exchange with the second fluid. That is, the conduit 2 has a temperature gradient depending on the flow direction of the first fluid. On the other hand, the temperature of the catalyst, which is an acicular powder, changes depending on the temperature of the first fluid. Therefore, the temperature of the first fluid is adjusted so that the catalyst has an optimal temperature at which the oxidation-reduction reaction occurs, thereby promoting the oxidation-reduction reaction. Although it is possible to precipitate the SO ₂ if they have water at low temperatures, for redox reactions therefrom, because there is a range in temperature, the temperature changes toward the downstream from the upstream of the first fluid, in this catalyst A temperature gradient is provided so that an oxidation-reduction reaction is suitably caused in any region.

  If the second fluid contains sulfides, the combustion converts the sulfur to sulfur dioxide, which contacts oxygen and the catalyst to convert to sulfur trioxide. Then, the sulfur trioxide reacts with the catalyst and moisture in the air to form sulfuric acid in a high heat state. At this time, the first fluid can be heated by the high-temperature heat generation. Further, even in the case of changing to sulfuric acid in this way, since the conductive tube 2 and the fins 3 are coated with the resin, the corrosion of the conductive tube 2 and the like can be prevented.

  As described above, according to the above-described embodiment, the first fluid is provided with the conduction pipe 2, and the second fluid is passed outside the conduction pipe 2, so that the first fluid passes through the conduction pipe 2. In the heat exchanger 1 which performs heat exchange in the above, a catalyst that undergoes a reduction reaction with sulfides and nitrogen oxides contained in the second fluid is provided on the conducting tube 2 or the fins 3 provided so as to cross the conducting tube 2. Thus, the sulfide can be converted to sulfuric acid and removed through the catalyst. At this time, by changing the temperature of the first fluid flowing through the conduit 2, the temperature can be set to an optimum temperature at which the catalyst acts.

  In addition, a needle-like powder of carbon fiber was used as the catalyst, and this was provided so that the tip portion could protrude from the resin, so that heat exchange was performed between the base end portion and the tip portion of the carbon fiber. As a result, the contact area with the second fluid at the protruding tip portion can be increased, and the effect of the catalyst can be further enhanced.

  The present invention is not limited to the above embodiment, but can be implemented in various modes.

  For example, in the above-described embodiment, the heat exchanger 1 having the flat conductive tube 2 has been described as an example. However, the present invention is not limited to this, and the heat exchanger 1 having the meandering conductive tube 2 may be used. You may.

  Further, in the above embodiment, the resin containing carbon fiber is applied to the conductive tube 2, the fins 3, and the like, but the resin may not adhere to the metal surface. For this reason, another coating layer may be formed very thinly on the metal surface to enhance the adhesion between the metal layer and the resin layer.

  Further, in the above embodiment, the average fiber length of the carbon fibers was about 1 μm to 1000 μm, but the average fiber length was such that a nano-level carbon fiber powder was added. Is also good. With this configuration, it is possible to fill the space between the carbon fibers having a long fiber length with the carbon fibers having a short fiber length, thereby increasing the effect of thermal conductivity, and in a case where the resin is worn. Also, the surface of the conduit 2 can be covered with nano-level carbon fibers to prevent corrosion.

DESCRIPTION OF SYMBOLS 1 ... Heat exchanger 2 ... Conducting tube 3 ... Fin

Claims (6)

A heat exchanger that includes a conduction pipe that allows the first fluid to pass therethrough and allows the second fluid to pass outside the conduction pipe, thereby performing heat exchange with the first fluid that is passed through the conduction pipe.
A heat exchanger in which a catalyst that undergoes a reduction reaction with sulfides and nitrogen oxides contained in the second fluid is provided in a conduit or a fin provided to cross the conduit. The heat exchanger according to claim 1, wherein the catalyst is provided on a surface of a conduit or a fin via a resin. The heat exchanger according to claim 1, wherein the catalyst is provided so as to be exposed from the resin when the catalyst is provided on the surface of the conduit or the fin via the resin. The heat exchanger according to claim 1, wherein the catalyst is constituted by needle-like particles. The heat exchanger according to claim 1, wherein the catalyst is a needle-like carbon fiber. In the resin applied to the heat exchanger that performs heat exchange between the first fluid passed through the conduit and the second fluid passed outside the conduit,
A resin provided so that carbon fibers can be exposed from the surface of the coating film.

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