JP2018172708A - Carburization device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carburization device capable of reliably preventing soot from flowing to a device and pipeline after a washing device.SOLUTION: A carburization device 11 comprises: a carburizing atmosphere gas producing device 12 for producing carburizing atmosphere gas used for carburization treatment; a washing device 14 for feeding the carburizing atmosphere gas derived from the carburizing atmosphere gas producing device 12 to washing liquid, and washing it; a dehumidifier 15 for removing moisture contained in the carburizing atmosphere gas washed by the washing device 14; and a carburization furnace 16 for performing gas carburization treatment by heating a treated material while introducing the carburizing atmosphere gas dehumidified by the dehumidifier 15. The washing device 14 stores the washing liquid at a lower part, is provided with a gas phase part 14a at an upper part, and has a gas washing nozzle 18 for dropping the washing liquid to the gas phase part 14a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a carburizing apparatus, and more particularly, to a carburizing apparatus including a cleaning device that sends a cleaning gas containing a carburizing atmosphere gas containing carbon monoxide and hydrogen generated by a carburizing atmosphere gas generation device into a cleaning liquid.

  A general gas carburizing process is performed by heating a material to be treated while introducing a carburizing atmosphere gas containing carbon monoxide and hydrogen into a carburizing furnace. After mixing hydrogen gas and air, the mixed raw material gas is introduced into a carburizing atmosphere gas generator having a nickel catalyst layer maintained at a high temperature, and oxygen in the air and hydrocarbons are reacted with each other to carry out monoxide oxidation. An air mixing method for obtaining a carburizing gas containing carbon and hydrogen is widely used (see, for example, Patent Document 1).

  However, since the air used as the oxygen source contains about 78% (volume%, hereinafter the same) nitrogen, the concentration of carbon monoxide and hydrogen in the carburizing gas to be generated is higher than a predetermined concentration. There was a problem that it should not be. Specifically, for example, when methane gas is used as the carbon source, the carbon monoxide concentration is 20%, and when butane gas is used, 23.5% is the limit.

  By the way, in the gas carburizing process, it is known that when the carbon monoxide concentration in the carburizing gas is low, it is difficult to obtain a stable carburizing atmosphere in the carburizing furnace. In particular, in high-temperature rapid carburizing treatment, this tendency becomes remarkable due to gas equilibrium at high temperature. For this reason, the carburizing atmosphere gas with a high carbon monoxide density | concentration is calculated | required.

  Moreover, by increasing the carbon monoxide concentration in the carburizing gas, for example, when carburizing a part having a hole as a material to be processed, carburize sufficiently and evenly to the back of the hole. When carburizing is performed while stacking small parts and transporting them with a belt, there is an advantage that the thickness of the parts stacked on the belt can be increased.

JP 2004-332080 A JP 2000-256824 A JP 2008-290905 A Japanese Unexamined Patent Publication No. 2015-4109 JP 2006-122862 A

  By the way, as a method of increasing the carbon monoxide concentration in the carburizing gas, a method of generating by carbon dioxide gas instead of air mixed with hydrocarbon gas is known (for example, Patent Documents). 2). Theoretically, for example, when the transformation reaction is performed at a molar ratio of methane gas to carbon dioxide of 1: 1, 2 mol of carbon monoxide and 2 mol of hydrogen are produced, and the concentration of both is 50%. Become. Further, when butane gas is used as the hydrocarbon, 8 mol of carbon monoxide and 5 mol of hydrogen are generated by reaction with 4 mol of carbon dioxide.

  However, when generating carburizing gas, if carbon monoxide gas is used instead of air as an oxygen source to generate high-concentration carbon monoxide, soot is generated in the carburizing atmosphere gas generator, and soot removal is performed. It took a lot of work.

  In addition, when generating carburizing gas, air that does not use air as the oxygen source is mixed with a hydrocarbon gas and water vapor to add the oxygen gas to the raw material gas, and the carburizing atmosphere in the electric furnace. A method of generating gas is disclosed (for example, see Patent Document 3). However, soot accumulates with the temperature drop in the electric furnace and the generation of the carburizing atmosphere gas, and there is a problem that the composition of the carburizing atmosphere gas varies and the continuous operation time decreases.

  Further, when the carburizing atmosphere gas is generated, the hydrocarbon and oxygen are burned as a swirling flame to generate the carburizing atmosphere gas. It has occurred. In addition, the carburizing atmosphere gas generating device is required to operate continuously for a long time depending on the processing state of the material to be processed, but there may be a problem in the processing state due to the generation and deposition of a small amount of soot. Driving could not be continued.

  As a countermeasure against the above-mentioned soot, there is a method in which soot generated with the generation of the carburizing atmosphere gas and carried together with the carburizing atmosphere gas is bubbled with a cleaning device before being introduced into the carburizing furnace. (For example, refer to Patent Document 4).

  However, since soot is hydrophobic, it is very difficult to mix with water, and soot that cannot be mixed by bubbling may be brought into the piping after the cleaning device, dehumidifier, or even carburizing furnace and deposited. It was necessary to remove the soot. Further, when soot is brought into the carburizing furnace, there is a possibility that the gas composition fluctuates in the carburizing furnace.

  On the other hand, as a method of removing the substance in the gas, an absorption cylinder having a spray header for injecting the absorption liquid upward is formed, and the exhaust gas introduced from the lower part of the absorption cylinder and the absorption liquid injected from the spray header are gas-liquid A method is disclosed in which the exhaust gas is desulfurized by contact (see, for example, Patent Document 5). However, when such an absorption cylinder is used for removing soot from the carburizing atmosphere gas, although the gas-liquid contact is increased by making the flow direction of the cleaning liquid and the carburizing atmosphere gas the same, the cleaning liquid is used together with the carburizing atmosphere gas. There is a problem that impurities are carried to the supply destination of the carburizing atmosphere gas, and there is also a possibility of depositing in the piping.

  Then, this invention aims at providing the carburizing apparatus which can prevent reliably that a soot flows into the apparatus and piping after a washing | cleaning apparatus.

  In order to achieve the above object, the carburizing apparatus of the present invention is a carburizing atmosphere that generates a carburizing atmosphere gas containing carbon monoxide and hydrogen used for carburizing treatment by a combustion reaction between a hydrocarbon gas and a combustion-supporting gas. A gas generating device, a cleaning device for sending the carburizing atmosphere gas derived from the carburizing atmosphere gas generating device into a cleaning solution for cleaning, and removing moisture contained in the carburizing atmosphere gas cleaned by the cleaning device And a carburizing furnace that performs a gas carburizing process by heating a material to be treated while introducing the carburizing atmosphere gas dehumidified by the dehumidifier. In addition, a gas phase part is provided in the upper part, and a gas cleaning nozzle for dropping the cleaning liquid in the gas phase part is provided.

  Moreover, it is preferable that the gas cleaning nozzle is provided at an upper part of a gas outlet of the cleaning device and drops the cleaning liquid in a curtain shape. Further, a cleaning liquid that has been cleaned from the carburizing atmosphere gas is derived from the cleaning apparatus, and a cleaning liquid filtering apparatus that filters the carburizing atmosphere gas is provided, and a part of the filtrate filtered by the cleaning liquid filtering apparatus is supplied to the gas cleaning nozzle. It is preferable.

  According to the carburizing apparatus of the present invention, the soot generated when generating the carburizing atmosphere gas is removed by bubbling with the cleaning device, and the soot remaining in the gas phase portion without being dissolved in the cleaning liquid is removed by the gas cleaning nozzle. Since it can be removed by the washing liquid to be dropped, it is possible to reliably prevent the soot from being brought into the carburizing furnace. Furthermore, since stable carburizing atmosphere gas can be generated, the yield of product processing can be improved.

It is a systematic diagram of the carburizing device showing an example of the present invention. It is principal part explanatory drawing which similarly shows a washing | cleaning apparatus. It is a top view of a washing device similarly.

  FIGS. 1 to 3 are views showing an embodiment of the carburizing apparatus of the present invention. As shown in FIG. 1, the carburizing apparatus 11 of the present embodiment is carburized containing carbon monoxide and hydrogen used for carburizing treatment. A carburizing atmosphere gas generating device 12 for generating an atmospheric gas, a heat exchanger 13 for cooling the carburizing atmosphere gas derived from the carburizing atmosphere gas generating device 12, and a cooled carburizing atmosphere gas being introduced into the cleaning liquid. The cleaning apparatus 14 for cleaning in this way, the dehumidifier 15 for removing moisture contained in the carburizing atmosphere gas cleaned by the cleaning apparatus 14, and the material to be treated are heated while introducing the carburizing atmosphere gas dehumidified by the dehumidifier 15. And a carburizing furnace 16 for performing a gas carburizing process. The cleaning device 14 is connected to a cleaning liquid filtering device 17 for filtering and removing soot trapped in the cleaning liquid.

  The carburizing atmosphere gas generator 12 has a large-diameter lower cylinder 12b connected to a lower part of a small-diameter upper cylinder 12a whose upper end is closed, and a combustion chamber 12c is formed inside the upper cylinder 12a. In the combustion chamber 12c, hydrocarbon gas ejection holes for supplying a hydrocarbon gas as a raw material gas and oxygen gas ejection holes for supplying an oxygen gas are alternately provided, and the hydrocarbon gas ejection holes are carbonized. A hydrogen gas supply pipe 12d is connected via a flow rate adjusting valve 12e, and an oxygen gas supply pipe 12f is connected to the oxygen gas ejection hole via a flow rate adjusting valve 12g.

  In the combustion chamber 12c, since the raw material gas is introduced as a swirling flow and becomes a swirling flow flame, the surface of the inner peripheral wall of the combustion chamber 12c is not directly heated by the flame, but oxygen gas is used. In view of manufacturability, it is desirable to use a metal such as SUS. Further, the combustion chamber 12c may adopt a water cooling structure using a Cu material having a high thermal conductivity as a main material in consideration of safety. However, since it affects the composition of the generated gas, it is necessary not to extremely cool the combustion chamber 12c.

  The lower cylinder 12b is provided with a cylindrical internal space having a volume larger than that of the combustion chamber 12c so as to communicate with the combustion chamber 12c, and a carburizing atmosphere gas lead-out path L1 is connected to the bottom. In the internal space, a catalyst layer 12h is provided at the bottom, and the catalyst layer 12h causes hydrocarbons contained in the carburizing atmosphere gas generated in the combustion chamber 12c to react and be removed. In addition, a required space is secured above the catalyst layer 12h, and a retention chamber 12i is formed by this space.

The catalyst constituting the catalyst layer 12h is not particularly limited as long as it can convert the hydrocarbon into carbon monoxide (CO) and hydrogen (H ₂ ). For example, a nickel catalyst is used. It is preferable. In selecting a catalyst, it is necessary to select a catalyst that does not impair the catalyst function depending on the gas temperature to be generated. Note that the catalyst layer 12h may be provided separately and provided at the subsequent stage of the combustion chamber 12c.

  The residence chamber 12i has a stable gas flow rate when there is some variation in the generated gas flow rate, temperature, or composition when the raw material gas is burned in the combustion chamber 12c to generate a carburizing atmosphere gas. , Function as a buffer layer for generating a carburizing atmosphere gas at temperature and composition. In this embodiment, the staying chamber 12i is provided in the lower cylinder 12b. However, the staying chamber 12i may be formed separately from the carburizing atmosphere gas generator 12 and provided in the subsequent stage of the combustion chamber 12c. .

  Further, the hydrocarbon gas as a raw material is not particularly limited, and general hydrocarbon gas such as methane gas, propane gas, butane gas, city gas, LPG can be used, and the supply form of hydrocarbon gas is A hydrocarbon gas generator or a cylinder filled with hydrocarbon gas can be applied. Furthermore, the supply form of the oxygen gas used as a raw material is not particularly limited, and may be an oxygen gas generator such as oxygen PSA or a cylinder filled with oxygen gas. The concentration of oxygen gas is preferably in the range of 93 to 100%, and the oxygen gas used may be diluted with an inert gas such as nitrogen gas or air.

  The heat exchanger 13 rapidly cools the carburizing atmosphere gas by cooling means for introducing and quenching the carburizing atmosphere gas generated by the carburizing atmosphere gas generating device 12 through the carburizing atmosphere gas lead-out path L1. Therefore, it is preferable to suppress the generation of soot due to the Boudoor reaction and to have a capability of rapidly cooling to a temperature of 50 ° C. or less at a rate of 2000 ° C./sec.

  The cleaning device 14 is a carbon removing means provided to remove a small amount of soot (carbon) in the carburizing atmosphere gas generated by the carburizing atmosphere gas generating device 12, and a gas flow path downstream of the heat exchanger 13. The carburizing atmosphere gas provided through L2 is bubbled and washed in the cleaning liquid stored in the lower part of the cleaning device 14 to remove the soot from the carburizing atmosphere gas. Further, a gas cleaning nozzle 18 is attached to the upper inner wall of the cleaning device 14 to drop the cleaning liquid to the gas phase part 14a provided on the upper part of the cleaning liquid. The gas cleaning nozzle 18 injects a part of the cleaning liquid filtered and returned from the cleaning liquid filtering device 17 to the cleaning device 14 and drops it to the gas phase portion 14a, thereby remaining in the carburizing atmosphere gas of the gas phase portion 14a. The soot is dropped into the cleaning liquid in the state of being accompanied by splashing or in a gas-liquid mixed state, and the soot that cannot be removed by bubbling to the cleaning liquid is removed.

  Note that the cleaning device 14 may be directly connected to the carburizing atmosphere gas lead-out path L1 without providing the heat exchanger 13. Further, the cleaning liquid is not limited to water, and may be an aqueous solution that absorbs acidic gas.

  The dehumidifier 15 is a moisture removing means provided to remove moisture in the carburizing atmosphere gas cleaned by the cleaning device 14 and removes moisture contained in the carburizing atmosphere gas supplied to the carburizing furnace 16. , Preventing the decarburization reaction. Although the method of dehumidification is not specifically limited, The apparatus which dehumidifies to a dew point of 0 degrees C or less is preferable. The cleaning device and the dehumidifier 15 are connected by a pipe 19 serving as a carburizing atmosphere gas flow path L6, and the dehumidifier 15 and the carburizing furnace 16 are respectively connected by a pipe 20 serving as a carburizing atmosphere gas flow path L6. ing.

  The cleaning liquid filtration device 17 includes a gas-liquid separator 21 and a filter 22, and the cleaning liquid discharged from the cleaning device 14 is introduced into the filter 22 through the gas-liquid separator 21 by the cleaning liquid flow path L 3 and filtered. The cleaning liquid is filtered with the filter of the vessel 22. Further, the cleaning liquid filtered by the filter 22 is returned to the cleaning device 14 via the first circulation path L4 and supplied to the gas cleaning nozzle 18 via the second circulation path L5.

  As shown in FIGS. 2 and 3, the gas cleaning nozzle 18 has an outlet width equal to or equal to the outlet width at the upper part of the gas outlet 19a of the cleaning device 14 in order to ensure that the cleaning liquid is brought into contact with the carburizing atmosphere gas. It is preferable to dispose the cleaning liquid in a curtain shape with a wider width. Further, the number of cleaning holes 18a of the gas cleaning nozzle 18 is 4 or more, preferably 8 and the diameter of the opening is preferably 0.1 mm to 10 mm. Further, the interval between the cleaning holes 18a is preferably 0 mm (slit) to 10 mm, but the outlet interval is not particularly limited as long as the cleaning liquid falls in a curtain shape. The opening shape of the cleaning hole 18a is not limited to a circle. Further, the cleaning holes 18a are not limited to being arranged in a row, and may be arranged in a plurality of rows, and the flow rate of the cleaning liquid is 0.1 L / min or more, and preferably 1 L / min to 3 L / min. Further, the cleaning liquid dropped on the gas phase portion 14a may be in the form of mist or droplets.

  In addition, you may make it make a washing | cleaning liquid fall to the whole gaseous-phase part 14a, and can also make a washing | cleaning liquid fall to the piping 19 which connects the washing | cleaning apparatus 14 and the dehumidifier 15. FIG. Furthermore, the gas cleaning nozzle 18 is not limited to the one supplied with the cleaning liquid filtered by the cleaning liquid filtering device 17, and the cleaning liquid can be supplied from the outside.

  Since the cleaning device 14 according to the present embodiment is formed as described above, the soot remaining in the carburizing atmosphere gas in the gas phase portion 14a that cannot be removed simply by bubbling and cleaning the carburizing atmosphere gas in the cleaning liquid. Since it can be removed by the cleaning liquid dropped from the gas cleaning nozzle 18, soot in the carburizing atmosphere gas can be reliably removed. As a result, it is possible to prevent soot from accumulating in the pipes 19 and 20, the dehumidifier 15 and the carburizing furnace 16 disposed after the cleaning device 14, and to enable continuous operation of the carburizing atmosphere gas generating device 12. Furthermore, it becomes possible to continuously supply a stable carburizing atmosphere gas to the carburizing furnace 16, thereby improving the yield of product processing.

  Next, the results of comparing the removal state of soot using the carburizing atmosphere gas generation device (Examples 1 and 2) of this embodiment and another carburizing atmosphere gas generation device (Comparative Example 1) will be described. .

Example 1
Using the carburizing apparatus 11 of the present embodiment shown in FIG. 1, first, the carburizing atmosphere gas generating apparatus 12 stably generates carburizing atmosphere gas containing carbon monoxide at a high concentration (of the carburizing atmosphere gas generating apparatus). Steady operation) was confirmed. The steady conditions at this time were raw material gas: LPG and oxygen, oxygen ratio: 0.4, and a mixed gas containing about 40% carbon monoxide and about 55% hydrogen was generated. Thereafter, a small amount of soot contained in the carburizing atmosphere gas was cleaned by the cleaning device 14. After the cleaning, the carburizing atmosphere gas and soot are brought into contact with a curtain-like filtrate that is dropped from the gas cleaning nozzle 18, and the carburizing atmosphere gas after contact is transferred from the dehumidifier 15 to the carburizing furnace 16 via the pipes 19 and 20. Introduced.

  The conditions of the curtain of the cleaning liquid by the gas cleaning nozzle 18 at this time are: flow rate: 0.1 to 1 L / min, number of curtains: 0 to 3, opening diameter of cleaning hole 18a: 2.17 mm, number of cleaning holes 18a: 8 The interval between the cleaning holes 18a was 1 mm. Thereafter, the presence or absence of soot was visually confirmed with respect to the dehumidifier 15, the pipes 19 and 20, and the carburizing furnace 16, and the results are shown in Table 1. The case where no soot deposition was confirmed was marked with ◎, the case where soot deposition was confirmed in a very small amount was marked with ○, and the case where soot deposition was confirmed was marked with ×.

  Table 1 confirms that there is no cleaning liquid curtain by the gas cleaning nozzle 18 so that no soot is deposited on the dehumidifier 15, the pipes 19, 20, and the carburizing furnace 16, and a larger number of curtains is preferable. I understood that.

(Example 2)
The conditions of the gas cleaning nozzle 18 of the apparatus of Example 1 were changed, and other conditions were the same as in Example 1, and a trace amount of soot contained in the carburizing atmosphere gas was cleaned by the cleaning apparatus 14. The conditions of the curtain of the filtrate by the gas cleaning nozzle 18 are as follows: flow rate: 0.1 to 1 L / min, number of curtains: 0 to 3, opening diameter of the cleaning hole 18a: 4.35 mm, number of cleaning holes 18a: 6, The interval between the cleaning holes 18a: 2 mm. The presence or absence of soot accumulation in the dehumidifier 15, the pipes 19 and 20, and the carburizing furnace 16 was visually confirmed, and the results are shown in Table 2.

  Table 2 confirms that there is no filtrate in the dehumidifier 15, the pipes 19, 20, and the carburizing furnace 16 due to the filtrate curtain by the gas cleaning nozzle 18, and the number of curtains can be increased. It turned out to be preferable. Further, from Tables 1 and 2, it was found that the effect of removing wrinkles was higher when the interval between the cleaning holes 18a was narrowed.

(Comparative Example 1)
A gas cleaning nozzle that blows up the cleaning liquid is disposed below the gas outlet 19a of the cleaning device 14, and a trace amount of soot contained in the carburizing atmosphere gas is cleaned by the cleaning device 14 under the same conditions as in the first embodiment. . The conditions of the curtain of the filtrate by the gas cleaning nozzle 18 are: flow rate: 0.1 to 1 L / min, number of curtains: 0 to 3, opening diameter of the cleaning hole 18a: 2.17 mm, number of cleaning holes 18a: 8, The interval between the cleaning holes 18a was set to 1 mm. The presence or absence of soot accumulation in the dehumidifier 15, the pipes 19 and 20, and the carburizing furnace 16 was visually confirmed, and the results are shown in Table 3.

  According to Table 3, in the fountain-type curtain that blows the filtrate from below, it is confirmed that soot is accumulated in the dehumidifier 15, the pipes 19 and 20, and the carburizing furnace 16, and the effect of removing soot is small. As in 1 and 2, it has been found that a curtain of filtrate by a gas washing nozzle 18 that allows the filtrate to fall from the top is desirable.

  DESCRIPTION OF SYMBOLS 11 ... Carburizing apparatus, 12 ... Carburizing atmosphere gas generating apparatus, 12a ... Upper cylinder, 12b ... Lower cylinder, 12c ... Combustion chamber, 12d ... Hydrocarbon gas supply pipe, 12e ... Flow control valve, 12f ... Oxygen gas supply pipe, 12g ... Flow rate adjusting valve, 12h ... Catalyst layer, 12i ... Residence chamber, 13 ... Heat exchanger, 14 ... Cleaning device, 14a ... Gas phase section, 15 ... Dehumidifier, 16 ... Carburizing furnace, 17 ... Cleaning fluid filtration device, 18 DESCRIPTION OF SYMBOLS ... Gas cleaning nozzle, 18a ... Cleaning hole, 19 ... Pipe, 19a ... Gas outlet, 20 ... Pipe, 21 ... Gas-liquid separator, 22 ... Filter, L1 ... Carburizing atmosphere gas lead-out path, L2 ... Gas flow path, L3 ... Cleaning liquid flow path, L4 ... First circulation path, L5 ... Second circulation path

Claims (3)

A carburizing atmosphere gas generating device that generates a carburizing atmosphere gas containing carbon monoxide and hydrogen used for carburizing treatment by a combustion reaction between a hydrocarbon gas and a combustion-supporting gas, and a carburizing atmosphere gas generating device derived from the carburizing atmosphere gas generating device. A cleaning device for sending the bubbling atmosphere gas into the cleaning liquid and bubbling; a dehumidifier for removing water contained in the carburizing atmosphere gas cleaned by the cleaning device; and the carburizing device dehumidified by the dehumidifier In a carburizing apparatus equipped with a carburizing furnace that performs a gas carburizing process by heating a material to be processed while introducing an atmospheric gas,
The carburizing apparatus is characterized in that the cleaning apparatus stores a cleaning liquid in a lower part, a gas phase part is provided in an upper part, and a gas cleaning nozzle for dropping the cleaning liquid in the gas phase part. The carburizing apparatus according to claim 1, wherein the gas cleaning nozzle is provided at an upper portion of a gas outlet of the cleaning apparatus and drops the cleaning liquid in a curtain shape. Deriving a cleaning liquid that has washed the carburizing atmosphere gas from the cleaning apparatus, and providing a cleaning liquid filtering apparatus that filters with a filter, and supplying a part of the cleaning liquid filtered by the cleaning liquid filtering apparatus to the gas cleaning nozzle. The carburizing apparatus according to claim 1 or 2, characterized in that

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