KR20010060950A - Fin type catalytic heat exchanger - Google Patents

Abstract

PURPOSE: A heat exchanger of a catalyst burning type is provided to supply heat to a heat medium by using catalyst reaction on surface of pins. CONSTITUTION: Inorganic composite such as gamma alumina is wash-coated on a surface of a metallic pin for conveniently attaching catalyst. Then, titanium and zirconium are post processed on a catalyst layer. Herein, the surface of the pin is processed in a sand blasting method for wash-coating the catalyst. Then, a pin typed heat exchanger coated by gamma alumina is heated at a temperature of 500deg.C for 5 hours. Then, the pin is dried at a temperature of 120deg.C for 6 hours after coating the catalyst. Burned gas at a first exhaust gas outlet(2) is reacted in a heat exchanger having a honeycomb catalyst for being exhausted. Herein, the exhaust gas includes heat for being used as a pre-heating air of the pin typed heat exchanger.

Description

Fin type catalytic heat exchanger

The present invention relates to a catalytic combustion heat exchanger for supplying heat to a heat medium using a catalytic reaction on a fin surface. Catalytic heat exchanger of the present invention is a technology that can be used as a replacement of the reboiler process of the refinery, a heating source for the production of fine chemicals, volatile organic solvents (VOC) and odor substance removal equipment, industrial and household clean heating device.

The heat exchanger technology using catalytic combustion has a separate type in which heat exchange is performed after catalytic combustion, and an integral type in which the functions of the catalytic combustion and the heat exchanger simultaneously occur.

In the separate type, heat transfer is performed by using exhaust gas after catalytic combustion and heat transfer is performed by using reaction heat of a catalyst supported on a pellet-type support. In both methods, high heat transfer efficiency cannot be expected and catalyst Is deteriorated and suffers from a lot of thermal shocks.

On the other hand, in the case of the integrated type, heat loss can be reduced as much as possible by directly exchanging heat generated by the catalytic reaction, and the heat transfer contact surface can be enlarged to obtain relatively high heat transfer efficiency, and the whole system can be miniaturized. .

In general, the one-piece type generally used is a form in which reaction heat by a porous catalyst is transferred into a tube, and despite a complicated structure, pressure loss is low, combustion reaction conversion rate and heat transfer efficiency are excellent, and its application range is known.

However, when the structure is complicated and clogging due to dust or condensate is concerned, it is restricted in use, and there is a disadvantage in that additional fuel supply by an auxiliary burner is required for the initial reaction start temperature of the catalyst. .

The present invention for solving the above problems corresponds to an integral type in which the catalytic combustion heat exchanger is also the catalytic combustion and heat exchange at the same time, the mixed gas coming from the mixed gas inlet (1) of the fuel and air as shown in FIG. In the catalyst layer (4) supported on the surface is burned by the surface reaction, the heat generated is heat transfer (7) to the heat medium through the fin (3) and the tube.

The structure of the fin on which the catalyst is supported uses a shape designed to maximize a sufficient surface reaction and heat transfer area with the fin 3 in consideration of the inflow direction of the mixed gas inlet 1 as shown in FIG. 2. The eight grooves formed in the fin serve to facilitate the incoming mixed gas inlet (1) to smoothly contact another pin located at the rear end, and the fins (3) and the mixed gas inlet (1) Contact time can be expected, and smooth surface reaction and heat transfer improvement can be obtained. In order to maximize this effect, the grooves of the first pin and the next pin are staggered without being aligned. In addition, the fin type is less dependent on the impact of the thermal shock than the conventional catalyst support such as wire-mesh or metal sponge (sponge), it can minimize the generation of condensate due to rapid heat transfer to the heat medium.

Natural gas, which is widely used as gaseous fuel, and by-product gas of recyclable oil refinery contains a large amount of sulfur compounds, so research on sulfur poisoning is important in the process using catalytic combustion. The presence of sulfur in various chemical forms depends on the reaction conditions, and for most catalysts, the adsorption of sulfur is an important factor in the electrical and structural properties of the surface. They also have a large effect on the catalytic properties, and the sulfur present in the catalyst may adversely affect the adsorption or desorption of the molecular space in whole or in part, and may adversely affect the surface reaction between the adsorbed spaces. Sulfur-bonded metals and sulfur bonds are much stronger than metal-sulfur bonds in metal compounds. Due to the bond strength of metals and sulfur, the adsorption of sulfur is often different than expected in the catalyst bed. Therefore, it is difficult to provide basic information on the poisoning.

1 is a structure of a fin type catalytic combustion heat exchanger

2 is a structure and concept of a pin loaded with a catalyst

3 is a performance analysis device of the fin type catalytic combustion heat exchanger

4 is the combustion characteristics of the heat-resistant and endothelial catalyst

5 is a conversion rate and heat transfer characteristics of the catalytic combustion heat exchanger

<Explanation of symbols for the main parts of the drawings>

(1): mixed gas inlet (2): exhaust gas outlet

(3): fin (4): catalyst layer

(5): heat medium inlet (6): heat medium outlet

(7): heat transfer (8): honeycomb catalyst

(9): exhaust

When described in detail with reference to the accompanying drawings, the configuration and the operation of the embodiment of the present invention to achieve the object as described above and to perform the task for eliminating the conventional drawbacks.

First of all, the external configuration of the gas and gas mixture (1) and the heat medium inlet (5) of the fuel and air communicate with the vertically erect body, and the primary exhaust gas outlet (2) and the heat medium outlet (6) communicate with each other. A plurality of fins 3 protrude from the inside of the heat exchanger and an outer surface thereof, and a catalyst layer 4 is supported on the surface of the fins 3.

Catalytic heat exchanger of the present invention is also a technology that can reuse the by-product gas discharged from the refinery as an energy source. In order to develop such a heat and endothelial catalyst, in the present invention, the catalyst is wash-coated with an inorganic compound such as gamma alumina (γ-Al ₂ O ₃₎ on the metal surface in order to properly attach the metal pin surface. Next, a noble metal catalyst was supported, and a method of post-treatment with titanium (Ti) and zirconium (Zr) metal on the supported catalyst layer was used. In order to wash-coate the catalyst on the fin, the surface is treated by sand blasting, washed with alcohol and hexane, followed by mixing and stirring gamma alumina, nitric acid and water. Wash-coating (wash coating) solution was prepared, and the prepared solution was coated on the surface of the pin.

The gamma alumina-coated fin heat exchanger was calcined by heating to 500 ° C. for 5 hours in an air atmosphere. Supporting the catalytically active material was carried on the noble metal catalyst of Pd (NO ₃ ) ₂ and Pt (H ₂ PtCl ₆ ) corresponding to 2.0wt% on it and dried at 120 ℃ for 6 hours.

The combustion gas of the primary exhaust gas outlet 2 produced by the catalytic reaction on the fin surface is again reacted and exhausted 9 in the combustor of the heat exchanger with honeycomb catalyst 8.

At this time, the generated exhaust gas contains high temperature heat, and is recovered again in the same manner as in FIG. 3 to be used as preheating air of the fin type heat exchanger.

Through this thermal circulation system, it is possible to save additional fuel for the auxiliary heat source required for preheating and continuous catalytic combustion, which has been pointed out as a problem in the heat exchanger system.

In addition, it is possible to obtain flexibility in fuel amount and combustion reaction in the fin-type catalytic heat exchanger, thereby controlling the amount of heat exchanger transferred to the heat medium.

The honeycomb catalyst (3) in the combustor of the secondary heat exchanger used 300 cell / in ² honeycomb (diameter 50 mm) composed of 50% cordierite and 50% mullite, and Pd (NO ₃₎ ), a catalyst layer was formed by using the _second and pimakje of γ-Al ₂ O ₃ sol.

(Example)

The fin tube of the fin catalytic combustion heat exchanger used in this experiment was made of SUH409 (11Cr-1.0Ti-0.06C, Fe balance). The outer diameter of the tube was 38 mm, and the maximum length of the tube on which the pin was formed was selected to be 110-360 mm. The thickness of the pin was 1.27 mm, and the pin height was 13.5-20 mm. In order to wash-coate the catalyst on the fin, the surface is treated by sand blasting, washed with alcohol and hexane, and then mixed and stirred with gamma alumina, nitric acid, and water. Wash-coating (wash coating) solution was prepared, and the prepared solution was coated on the surface of the pin. The gamma alumina-coated fin heat exchanger was calcined by heating to 500 ° C. for 5 hours in an air atmosphere. Supporting the catalytically active material was carried on the noble metal catalyst of Pd (NO ₃ ) ₂ and Pt (H ₂ PtCl ₆ ) corresponding to 2.0wt% and dried at 120 ° C. for 6 hours. In addition, in order to form a catalyst layer resistant to heat and endothelial poisoning, it was post-treated with zirconium and titanium on the supported catalyst layer. The honeycomb catalyst (3) in the combustor of the secondary heat exchanger used 300 cell / in ² honeycomb (diameter 50 mm) composed of 50% cordierite and 50% mullite, and Pd (NO ₃₎ ) to form a catalyst layer using the _second and pimakje of γ-Al2O3 sol.

(Legal interpretation of modified examples and applied examples)

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

3 is a schematic diagram of a performance analysis apparatus for a fin type catalytic heat exchanger. The mixed gas of the mixed gas inlet (1) of air and fuel is injected into the upper end of the vertically spaced catalytic heat exchanger to react on the surface of the fin (3) on which the catalyst is supported, and then exhausted from the exhaust gas outlet (2) to the lower end. It is done. At this time, the exhaust gas is burned again in the second honeycomb catalyst (8) heat exchanger and exhausted (9) as a complete combustion gas. The heat medium flowing into the heat exchanger was tested using an oil (soybean oil) having a vaporization point of 250-280 ° C. which does not cause a phase change even at a temperature of 100 ° C. or higher, and absorbed heat generated from the catalyst layer to be discharged. The circulation of the heat medium was supplied using a gear pump, and the flow amount was confirmed by a flow meter. In addition, since the inlet temperature of the heat medium can have a great influence on the combustion reaction in the overall catalyst bed, it is selected after supplying the temperature through the heater in the oil tank, and in order to make the temperature in the oil tank uniform. Was installed to prevent evaporation of oil by local heating in the tank. The temperature distribution of the catalyst layer and the temperature of the heat medium during the combustion reaction were measured by installing a thermocouple. The components and composition of the reactants and products generated in each part of the catalyst layer during the combustion reaction were analyzed using a gas analyzer connected online.

In order to select a catalyst for the combustion of fuel gas, the poisoning property against sulfur of the prepared catalyst was investigated. Irradiation method is by injecting a gas mixture further H ₂ S gas from about 1300ppm in the reaction of CH ₄ of the combustion was compared to combustion activity of the catalyst for the CH _4. Figure 4 shows the degree of poisoning of the catalyst by the sulfur compound. As a result of the cycle reaction with Pd (2) / γ-Al ₂ O ₃ catalyst (-▲-) irradiated in the absence of H ₂ S gas, there is little reduction in CH ₄ combustion activity of T ₅₀ from about 250 ℃ to 270 ℃. However, in the condition (●) containing H ₂ S, the catalytic activity of T ₅₀ was significantly decreased from about 370 ° C. to 470 ° C. However, the addition of zirconium showed a slight decrease in the initial activity even with H ₂ S gas, but there was no significant difference in the activity even after repeated experiments. In addition, the combustion activity of CH ₄ was compared in the same way for the binary metal catalyst further loaded with titanium and tin, but the activity retention was deeper than that of the zirconium supported catalyst.

5 is a fin type catalytic heat exchanger according to the amount of heat medium (oil) temperature is constant at 140 ^o C in the condition that the air volume is 50L / min and the amount of LPG gas mixture is 1.72L / min and the excess air ratio is 1.25 Shows combustion reaction and heat transfer characteristics. When oil is not introduced, heat loss to the heat medium does not occur, so the reaction temperature at the surface of the fin is kept high and the activity of the catalyst is good by the combustion reaction. However, as the oil starts to flow, the combustion conversion rate (1st) tends to decrease. This is because the heat of reaction is transferred to the heat medium through the fins, which affects the surface temperature of the fins, which deteriorates the combustion reaction activity. However, after the oil was introduced, there was no significant change in the combustion conversion rate even if the amount of oil continued to increase. The conversion rate 2nd is a result after reacting the combustion gas generated in the primary fin catalytic reaction again with the secondary honeycomb catalyst, and it can be seen that complete combustion has been achieved. The high temperature heat obtained through the secondary combustion was recovered again as shown in FIG. 3 and used as preheating air of the fin type heat exchanger, thereby reducing the additional fuel required for the auxiliary heat source required for preheating.

Claims (5)

It has a fin 3 structure, in which a mixed gas of air and fuel is combusted by surface reaction in the catalyst layer supported on the surface of the fin 3, and transfers the reaction heat obtained from the fin to the heat medium flowing through the tube through the fin and tube. Fin-type catalytic combustion heat exchanger, characterized in that. The method of claim 1, Considering the flow of mixed gas of air and fuel in the combustor of the fin-type catalytic combustion heat exchanger, the actual heat transfer while maximizing the time that the mixed gas can contact the surface of the fin 3 and increasing the area that can be contacted Finned catalytic combustion heat exchanger, characterized in that a plurality of grooves in the fin surface and to arrange their positions with the next fin to minimize the reduction of the contact area for the. The method of claim 1, After washing-coating an inorganic compound such as gamma alumina (γ-Al ₂ O ₃ ) on the surface of the fin 3 of the fin-type catalytic combustion heat exchanger, the precious metal catalyst is supported thereon and titanium (Ti) And a catalyst layer (4) having a strong anti-toxicity against heat and sulfur obtained by post-treating a metal of zirconium (Zr). The method of claim 1, Combustion gas obtained by surface reaction in fin-type catalytic combustion heat exchanger is secondary burned in honeycomb catalyst and heat is recovered again from high-temperature exhaust gas to control combustion reaction and heat transfer in fin-type catalytic combustion heat exchanger. And at the same time, it is possible to reduce the energy required for auxiliary heat sources which must be additionally supported for preheating and continuous catalytic reaction in the combustor. The gaseous inlet (1) and the heat medium inlet (5) of fuel and air communicate with the upright body, and the primary exhaust gas outlet (2) and the heat medium outlet (6) communicate with each other. Fin-type catalytic combustion heat exchanger, characterized in that a plurality of fins (3) protruding in the portion and the catalyst layer (4) is supported on the surface of the fin (3).