JPH0418009B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an endothermic gas conversion device, and more specifically, the present invention relates to an endothermic gas conversion device, and more specifically, the endothermic gas used during heat treatment such as quenching and tempering of steel parts or carburizing and quenching is converted into an endothermic gas using a low-temperature active catalyst. This requires an endothermic gas shift device that can perform metamorphosis at a relatively low temperature of 850 to 950°C. [Prior art] Endothermic gas used during heat treatment such as hardening and tempering of steel parts or carburizing and quenching has conventionally been produced by an endothermic gas conversion device called a so-called RX gas generation furnace. . This RX gas generating furnace then supplies methane (CH ₄ ), ethane (C ₃ H ₈ ), butane (C ₄ H ₁₀ ), etc. into a retort filled with a nickel catalyst and maintained at a high temperature of 850 to 1100°C. This system supplies a mixed gas of hydrocarbon gas and air, and transforms an endothermic gas containing CO, H ₂ , and N ₂ as main components, and trace amounts of CH ₄ , H ₂ O, and C. . By the way, compared to the nickel catalyst used in the conventional RX gas generator mentioned above, the 850~
When using a cobalt catalyst that is active at 950℃, the endothermic gas conversion reaction, which could only be carried out at a high temperature of 850 to 1100℃ when using a conventional nickel catalyst, can be carried out at a relatively low temperature of 850 to 950℃. As a result, it has become clear that endothermic gases similar to those of the above-mentioned nickel catalyst can be modified. Now, if we take butane as an example of a hydrocarbon gas and observe its modification reaction, in the retort the reaction C ₄ H ₁₀ + 2O ₂ + 7.52N ₂ → 4CO + 5H ₂ + 7.52N ₂ proceeds, and at this time , the following equilibrium reaction is maintained. H ₂ +CO ₂ CO + H ₂ O CH ₄ +CO ₂ 2CO + 2H ₂ CH ₄ +H ₂ OCO + 3H ₂ Therefore, between each component, CO≒23%, H ₂ ≒29
%, CH ₄ = trace amount ~ 0.2%, CO ₂ = trace amount ~ 2.0%, and the balance is N ₂ , which are in equilibrium with each other. When the mixing ratio of butane and air is changed, the equilibrium values of CH ₄ , CO ₂ , H ₂ O, etc. change depending on the mixing ratio. At the same time, the equilibrium values of CO, H ₂ , N ₂ etc. also change, but the proportion thereof is small. By the way, in this conventional endothermic gas shift method, before the mixed gas of hydrocarbon gas and air contacts the catalyst and the shift reaction proceeds, the hydrocarbon gas is thermally decomposed to produce soot (C). When generated, the equilibrium state is disrupted and equilibrium gas cannot be obtained, resulting in CO, CO ₂
The disadvantage is that it is difficult to control the carbon potential. Furthermore, there is a drawback that the soot (C) produced as described above adheres to the catalyst, resulting in a decrease in catalytic activity. The drawbacks of the above-mentioned technology as described above will be explained based on a specific conventional device. In FIG.
When a mixed gas consisting of 0.86 l/min of butane 1 and 8.6 l/min of air 2 is fed to the retort 6 at 930°C, 15 l/min of endothermic gas flows under the catalyst 7 of 100 c.c. 3 can be transmuted. Here, in the conventional shift converter, in order to prevent thermal decomposition of the hydrocarbon gas in the retort 6, the rapid heating section 6a has a multi-tubular structure consisting of several small diameter pipes, which easily absorbs heat from the heating furnace. This is designed to promote rapid heating of the gas. That is, in this rapid heating section 6a, a mixed gas of air and butane is rapidly heated in order to suppress the generation of soot (C) due to the following thermal decomposition reaction of butane: C ₄ H ₁₀ →C↓2CH ₄ + _H 2 Needs to be heated. However, as mentioned above, the retort 6 of the conventional endothermic gas shift converter has a multi-tube structure of small diameter pipes, which is designed to promote rapid heating, but it does not completely prevent the generation of soot (C). has drawbacks that cannot be suppressed. [Object of the Invention] The present invention is directed to the use of an endothermic gas used in an atmosphere for heat treatment of steel parts, etc., to air that has been preheated to a high temperature using a cobalt catalyst that is active at a lower temperature than a conventional nickel catalyst. By mixing hydrocarbon gases at room temperature, heating the hydrocarbon gases with high heat transfer efficiency, and increasing the heating rate of the hydrocarbon gases, thermal decomposition of the hydrocarbon gases can be reliably suppressed. An object of the present invention is to provide an endothermic gas shift device that can efficiently transform endothermic gas in an equilibrium state through a catalytic reaction by having a structure that allows easy mixing of gas and air. [Structure of the Invention] According to the present invention, air and a hydrocarbon gas such as butane are supplied and mixed in a retort filled with a catalyst and maintained at a high temperature to produce an endothermic type gas. The retort is a cylindrical Laval tubular shape having a constricted part in the center, and is arranged in a heating furnace, and the retort is arranged inside the retort with the constricted part as a boundary. The retort is divided into an air preheating chamber and a catalyst filling section filled with catalyst with a mesh-like diaphragm, and a flow meter is installed at the end of the air preheating chamber side of the retort to measure and control the amount of air supplied from the air supply source. , an air supply pipe for feeding into the air preheating chamber is connected, and a heat insulating material having a cooling structure disposed on the furnace wall of the heating furnace is connected to the constriction section side of the in-retort catalyst filling chamber. A plurality of butane and other hydrocarbon gas supply pipes are connected from multiple directions by external piping through a flowmeter that measures and controls the amount of butane and other hydrocarbon gas supplied. Furthermore, this is achieved by an endothermic gas shift apparatus characterized in that the end of the retort on the side of the catalyst filling chamber has a cooler for cooling the shifted gas. [Action of the invention] The action of the present invention will be explained below. The difference between the endothermic gas shift device of the present invention and the conventional endothermic gas shift device lies in the structure for heating butane as a hydrocarbon gas and the structure for supplying it. Conventional endothermic gas shift equipment has a structure in which room temperature butane is rapidly heated together with room temperature air 10 times its volume, which slows down the heating rate of butane. A volume of air 10 times the amount of butane heated to
Since the butane is heated by direct contact with butane at room temperature, the heat transfer efficiency is very high, and the heating rate of butane is therefore fast, so the thermal decomposition of butane can be sufficiently suppressed and it becomes an endothermic gas in an equilibrium state. can be transformed. Furthermore, in the endothermic gas shift apparatus of the present invention, in order to prevent butane from being heated independently before being mixed with air, a heat insulating material is provided between the butane supply pipe and the furnace. Moreover, the heat insulating material is water-cooled. In addition, in the endothermic gas conversion apparatus of the present invention, since it is necessary to mix air and butane uniformly, as shown in FIG. The structure is such that butane is supplied from multiple directions to this constricted portion 6d and is delivered as a uniform mixed gas to the catalyst filling chamber 6b. [Example] Hereinafter, an example of the present invention will be described based on the accompanying drawings. FIG. 2 shows a schematic diagram of the endothermic gas shift apparatus of the present invention. In this embodiment, the same or corresponding parts as those in the conventional example shown in FIG. 1 are given the same reference numerals as in FIG. 1, and the explanation thereof will be omitted. In addition, in this example, as a hydrocarbon gas,
This will be explained using butane as an example. As is clear from FIG. 2, the configuration of the endothermic gas shift apparatus of the present invention is such that a butane flow meter 4, an air flow meter 5, an air preheating chamber 6a', and a catalyst filling chamber 6b are connected to a heat-resistant mesh-like diaphragm 6c. It consists of a retort 6, a catalyst 7, a cooler 8, and a heating furnace 9, which are divided into sections. The difference from the conventional endothermic gas shift apparatus is the butane 1 supply structure. Furthermore, as a point of the endothermic gas shift apparatus of the present invention, it is necessary to uniformly mix the air 2 and the butane 1, so the constricted part 6d of the retort 6 is formed at the confluence of the air 2 and the butane 1, Butane 1 is supplied from four directions perpendicular thereto, and the structure is such that it is delivered as a uniform mixed gas to the catalyst filling chamber 6b. In this manner, in the endothermic gas shift apparatus of the present invention, air 2 is heated to a high temperature of 930° C. at 8.6 l/min in the air preheating chamber 6d, and is maintained at room temperature by the piping outside the furnace. 0.86l/min of butane 1
is supplied from holes in four orthogonal directions drilled in a heat insulating material 10 that penetrates the heating furnace 9, and after rapidly heating the butane 1 in the catalyst filling chamber 6b, the oxygen excess rate is reduced. 1.05, the composition of which was mixed with air 2 and modified by cobalt catalyst 7 is shown in the table below.

[Function and effect of the invention]

As is clear from the above, according to the endothermic gas shift apparatus according to the present invention, the endothermic gas used in the atmosphere for heat treatment of steel parts, etc. is made using a cobalt catalyst that is active at a lower temperature than the conventional nickel catalyst. By directly mixing hydrocarbon gas at room temperature with air that has been preheated to a high temperature, the hydrocarbon gas is heated with good heat transfer efficiency, and the heating rate of the hydrocarbon gas is accelerated. By having a structure in which decomposition can be reliably suppressed and hydrocarbon gas and air are easily mixed, there is an advantage that an endothermic gas in an equilibrium state due to a catalytic reaction can be efficiently transformed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional endothermic gas shift device, and FIG. 2 is a schematic diagram of an endothermic gas shift device of the present invention. 1... Butane, 2... Air, 3... Endothermic gas, 4... Butane flow meter, 5... Air flow meter, 6
... Retort, 6a ... Rapid heating section, 6a' ... Air preheating chamber, 6b ... Catalyst filling chamber, 6c ... Meshed diaphragm, 6d ... Throttle section, 7 ... Cobalt catalyst, 8 ... Cooler, 9...Heating furnace, 10...Insulating material, 11...Cooling water piping.

Claims (1)

[Claims] 1. An endothermic gas shift device that supplies and mixes air and hydrocarbon gas such as butane in a retort filled with a catalyst and maintained at a high temperature to convert endothermic gas. The retort has a cylindrical shape in the form of a Laval tube with a constriction in the center, and is disposed in a heating furnace, and the retort is filled with an air preheating chamber and a catalyst, with the constriction as a boundary. The catalyst filling part is divided by a mesh-like diaphragm, and the end of the retort on the air preheating chamber side is supplied with air that is sent to the air preheating chamber via a flow meter that measures and controls the amount of air supplied from the air supply source. A pipe is connected to the constriction part side of the catalyst filling chamber in the retort, and a heat insulating material having a cooling structure provided on the wall of the heating furnace is disposed so as to pass through a heat insulating material having a cooling structure to absorb hydrocarbons such as butane. A plurality of butane and other hydrocarbon gas supply pipes are connected from multiple directions led by external piping through a flow meter that measures and controls the gas supply amount. An endothermic gas shift device characterized by having a structure including a cooler for cooling the metamorphosed gas.