JP6234711B2 - Carburizing gas production method and carburizing gas production equipment used therefor - Google Patents

Description

The present invention relates to a method for producing a carburizing gas used in a carburizing method for a steel member, and a carburizing gas production facility used therefor.

As one surface hardening method for steel members, a carburizing method using RX gas (carburizing gas) is known (for example, see Patent Document 1). The RX gas supply device in this carburizing method includes a nitrogen generator for supplying nitrogen gas containing a small amount of oxygen, a hydrocarbon supply device for supplying hydrocarbon gas, and a nitrogen gas adjusted to a predetermined supply amount, A low-temperature reaction vessel in which hydrocarbon gas is introduced and subjected to primary treatment, and a secondary mixer in which the primary treatment gas and hydrocarbon gas adjusted to a predetermined supply amount are introduced and mixed ing. And RX gas is made with the secondary mixer. Here, as the hydrocarbon supply device, a device capable of vaporizing liquefied high-purity hydrocarbon filled in a high-pressure vessel having a predetermined volume and adjusting the supply pressure to a desired supply pressure is used. Specific examples of the hydrocarbon include paraffinic hydrocarbons such as methane, ethane, propane, and butane. As described above, methane (natural gas) or the like is used as the raw material for the RX gas. Therefore, the composition of the RX gas is carbon monoxide gas (CO): 20 to 25 mol%, hydrogen gas ( H _2): 30 to 40 mol%, which is balance and nitrogen gas (N _2).

  By the way, the carburizing method using the RX gas is a gas carburizing method, and has a lower carburizing speed and a smaller number of treatments per unit time than the vacuum carburizing method.

JP 2012-32113 A

  Since the carburizing method using the gas carburizing method has a low carburizing rate as described above, an improvement in the carburizing rate is required to improve productivity.

This invention is made | formed in view of such a situation, The objective is to provide the manufacturing method of the carburizing gas used for the carburizing method which can speed up carburizing speed, and the carburizing gas manufacturing equipment used therefor.

In order to achieve the above object, the present invention is a method for producing a carburizing gas containing at least carbon monoxide gas and hydrogen gas, wherein natural gas is heated by a first heater and then passed through a desulfurizer. The first step for sending to the first pipe , the second step for heating oxygen gas with the second heater and sending to the second pipe, the gas that has passed through the first step and the gas that has passed through the second step are mixed. And passing the mixed gas through a reformer to generate a gas containing carbon monoxide gas and hydrogen gas, and the carbon monoxide gas and hydrogen gas obtained by the third step. The generated gas containing the gas is passed through the third pipe and the cooler in this order, and then gas-liquid is separated by the gas-liquid separator, and the liquid after the gas-liquid separation is externally discharged from the drain pipe. drained, the gas after it has been the gas-liquid separation from through a compressor suction holder, the gas A fourth step of compressing by the compressor, by passing the gas containing the fourth the carbon monoxide gas compressed by step and the hydrogen gas, the pressure swing adsorption system from through the fourth conduit And a fifth process for increasing the concentration of the carbon monoxide gas and hydrogen gas, and a carburizing gas production method for obtaining a carburizing gas having a carbon monoxide gas concentration in the range of 30 to 60 mol% This is the first gist.

The present invention is also a carburizing gas production facility used in the carburizing gas production method of the first aspect, wherein the first heater for heating natural gas and a desulfurizer for desulfurizing the heated natural gas are provided. And a first pipe through which the natural gas desulfurized by the desulfurizer is passed, a second heater for heating the oxygen gas, and an oxygen gas heated by the second heater are passed through and connected to the first pipe. a second conduit, a gas mixture of the desulfurizer at desulfurized oxygen gas delivered through a heated said second conduit in natural gas and the second heater transmitted through said first conduit A reformer that generates a gas containing carbon monoxide gas and hydrogen gas from the gas generator, and a third pipe that passes the generated gas containing the carbon monoxide gas and hydrogen gas generated by the reformer. A cooler for passing the product gas sent through the third pipe, A gas-liquid separator that gas-liquid separates the product gas partially liquefied through the vessel, a drain pipe that drains the liquid after the gas-liquid separation to the outside of the gas-liquid separator, and A compressor suction holder through which a gas containing the carbon monoxide gas and the hydrogen gas after gas-liquid separation is passed, a compressor that compresses the gas that has passed through the compressor suction holder, and compression by the compressor A carburizing gas production facility including a fourth pipe for passing the gas and a pressure swing adsorption device for passing the gas sent through the fourth pipe is a second gist.

  The present inventor conducted research on the composition of the carburizing gas in order to increase the carburizing rate. In the process, it was found that the carburization rate increased as the concentration of carbon monoxide gas increased. It was also found that the concentration of hydrogen gas has an effect on the carburization rate, and that the carburization rate increases when the hydrogen gas concentration is increased to some extent, but conversely the carburization rate decreases when the concentration is higher. As a result of further research, when the concentration of carbon monoxide gas is set to be in the range of 30 to 60 mol%, which is higher than before, hydrogen gas is also present moderately (35 to 55 mol%). As a result, it was found that the carburization rate was improved, and the present invention was reached.

Since the carburizing gas production method of the present invention includes the first to fifth steps, the concentration of carbon monoxide gas in the obtained carburizing gas is set to a relatively high concentration of 30 to 60 mol%. Can be set within range . The carburizing method using such a carburizing gas has a higher concentration of carbon monoxide gas than the conventional carburizing method, and can increase the carburizing rate.

  When the concentration ratio of carbon monoxide gas and hydrogen gas in the carburizing gas is set to 1: 1, the concentration of carbon monoxide gas and hydrogen gas is more optimized, and the carburization rate is increased. Can do.

  Since “1: 1” is a gas concentration ratio, not only accurate “1: 1” but also an error range of ± 5% [“(0.95 to 1.05): 1” Or “1: (0.95 to 1.05)”].

In addition, since the carburizing gas production facility of the present invention includes the above-described configuration such as the pressure swing adsorption device , the concentration of carbon monoxide gas is set within a relatively high concentration range of 30 to 60 mol%. and carburizing gas can Rukoto give.

The first embodiment of the carburizing process for gas Manufacturing equipment used in the carburizing treatment gas production method of the present invention is a configuration diagram schematically showing. It is a block diagram which shows typically 2nd Embodiment of the gas manufacturing equipment for carburizing treatment. It is a block diagram which shows typically 3rd Embodiment of the gas manufacturing equipment for carburizing treatment. It is a block diagram which shows typically 4th Embodiment of the gas manufacturing equipment for carburizing treatment.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

Figure 1 is a block diagram showing a first embodiment of the carburizing process for gas Manufacturing equipment used in the carburizing treatment gas production method of the present invention. In this embodiment, the carburizing gas production facility is such that the obtained carburizing gas has a carbon monoxide gas concentration and a hydrogen gas concentration of approximately 50 mol%.

That is, the carburizing gas production facility is configured to heat natural gas (consisting of a large amount of methane gas and a small amount of ethane gas, propane gas, sulfur, etc.) with the first heater 1 and then through the desulfurizer 2 to the first pipe. It will be sent to Road A. The oxygen gas is heated by the second heater 3 and sent to the second pipe B. The second pipeline B is connected to the first pipeline A, and the natural gas and the oxygen gas are mixed. Next, the mixed gas is passed through the reformer 4 to generate high-concentration carbon monoxide gas and hydrogen gas, which are then passed through the third pipe C. At the same time, carbon dioxide gas and water vapor are also generated. Subsequently, after passing them through the cooler 5, gas-liquid separation is performed by the gas-liquid separator 6, the liquid after the gas-liquid separation is drained to the outside from the drain pipe G , and the gas is sucked into the compressor suction holder 7. And then compressed by the compressor 8 and passed through the fourth pipe D. Thereafter, the gas compressed by the compressor 8 is passed through the pressure swing adsorption device 9, and the concentrations of the carbon monoxide gas and the hydrogen gas are both increased to about 50 mol%. As gas, it supplies to the conventionally well-known carburizing furnace which is not illustrated. The carbon dioxide gas adsorbed by the pressure swing adsorption device 9 is desorbed by using the vacuum pump 10 and incinerated by the flare stack 13. In the figure, the symbol V indicates a valve.

  Here, approximately 50 mol% of carbon monoxide gas and hydrogen gas obtained by the pressure swing adsorption device 9 are used in the carburizing furnace as the carburizing gas as described above. By using such a carburizing gas, the carburizing speed can be increased.

FIG. 2 is a configuration diagram showing a second embodiment of the carburizing gas production facility. The carburizing gas production facility of this embodiment is additionally provided with a hydrogen gas conduit and a carbon dioxide gas conduit in the first embodiment (see FIG. 1). That is, a hydrogen gas line is connected to a natural gas line, and after mixing natural gas and hydrogen gas, the gas is heated by the first heater 1 and then passed through the desulfurizer 2 to the first line A. To send. Then, a carbon dioxide gas pipe is connected to the oxygen gas pipe, the oxygen gas and the carbon dioxide gas are mixed, heated by the second heater 3 and sent to the second pipe B. In the second pipeline B, the mixed gas containing the natural gas and the mixed gas containing the oxygen gas are mixed. In addition, the carburizing gas production facility of this embodiment is additionally provided with a pipe F that branches between the vacuum pump 10 and the flare stack 13 in the first embodiment (see FIG. 1). . That is, carbon dioxide gas adsorbed by the pressure swing adsorption device 9 is desorbed by using the vacuum pump 10, most of the carbon dioxide gas is sent to the pipe F, passed through the compressor suction holder 11, and then compressed by the compressor 12. However, it is reused as a part of the raw material, and the remainder is incinerated by the flare stack 13.

  FIG. 3 is a configuration diagram showing a third embodiment of the carburizing gas production facility. The carburizing gas production facility of this embodiment is the same as that of the second embodiment (see FIG. 2), except that a liquid nitrogen tank 20 is added and the nitrogen gas obtained by vaporizing the liquid nitrogen is absorbed by the pressure swing adsorption. The mixed gas of about 50 mol% carbon monoxide gas and hydrogen gas obtained by the apparatus 9 is mixed. Other parts are the same as those in the second embodiment, and the same reference numerals are given to the same parts.

  In this embodiment, by mixing the nitrogen gas from the liquid nitrogen tank 20, the concentration of the carbon monoxide gas for carburizing treatment gas is reduced from about 50 mol% according to the object to be treated. Can be adjusted. The lower limit of the concentration of carbon monoxide gas is 30 mol%. By using such a carburizing gas, the concentration of carbon monoxide gas can be adjusted according to the material, thickness, etc. of the carburized object, and optimum carburizing can be performed.

FIG. 4 is a configuration diagram showing a fourth embodiment of the carburizing gas production facility. In the carburizing gas production facility of this embodiment, a carbon monoxide gas container 31 is added to the carburizing gas production facility shown in FIG. 2, and the carbon monoxide gas is used as the carburizing gas shown in FIG. It is mixed with RX gas obtained at the production facility, and the concentration of carbon monoxide gas can be increased. As a reference mode, a carbon monoxide gas container 31 is added to a conventional RX gas production facility 30 as described above, and the carbon monoxide gas is converted into conventional RX gas (carbon monoxide gas: 20 to 25). The carbon monoxide gas may be concentrated at a high concentration.

  In this embodiment, by mixing the carbon monoxide gas, as described above, the concentration of the carbon monoxide gas in the RX gas is increased to obtain a modified RX gas, and the material, thickness, etc. of the carburized object Depending on, it can be adjusted within the range of 30 to 60 mol%. By using such a carburizing gas, the carburizing speed can be increased. In addition, when the RX gas obtained at the carburizing gas production facility shown in FIG. 2 is insufficient in concentration, or when a carburized product is changed and a higher concentration is required, it can be quickly handled. become.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to the examples.

[Examples 1 to 3 and Comparative Examples 1 and 2]
A 2.5 mm thick plate of SUS316 (18% by weight of Cr, 12% by weight of Ni, 2.5% by weight of Mo, and the remainder of Fe) stipulated by Japanese Industrial Standards (JIS) is prepared and the carburizing furnace And heated to 450 ° C. and carburized using RX gas having the composition shown in Table 1 below. The carburizing treatment was performed so that the surface hardness was 870 to 890 Hv and the depth of the carburized layer was 20 μm. And the time required for the carburizing process was measured. The results are shown in Table 1 below.

  From the above results, Examples 1 to 3 in which the concentration of carbon monoxide gas in RX gas is 30 to 60 mol% are carburized compared to Comparative Example 1 in which the concentration of carbon monoxide gas is as low as 25 mol%. You can see that the speed is fast. In particular, Example 2 in which the concentration of carbon monoxide gas and the concentration of hydrogen gas are 50 mol% is the fastest. In addition, as in Comparative Example 2, it can be seen that even if the concentration of the carbon monoxide gas is made too high, such as 65 mol%, the concentration of hydrogen gas becomes as low as 35 mol%, so that the carburization rate becomes slow.

  The present invention can be used to increase the carburization rate.

DESCRIPTION OF SYMBOLS 1 1st heater 3 2nd heater 4 Reformer 9 Pressure swing adsorption device

Claims (11)

A method of manufacturing a carburizing gas containing at least carbon monoxide gas and hydrogen gas, was heated natural gas in the first heater, a first step of sending to the first conduit and passing the desulfurizer, The second step of heating the oxygen gas with the second heater and sending it to the second pipe, the gas having passed through the first step and the gas having passed through the second step are mixed, and the mixed gas is passed through the reformer. The third step of generating a gas containing carbon monoxide gas and hydrogen gas, and the generated gas containing the carbon monoxide gas and the hydrogen gas obtained by the third step are supplied to a third pipe. After passing through the passage and the cooler in this order, gas-liquid separation is performed by the gas-liquid separator, and the liquid after the gas-liquid separation is drained to the outside from the drain pipe, and after the gas-liquid separation is performed gas from the through compressor suction holder and a fourth step of compressing by the compressor to the gas, this The gas containing the said carbon monoxide gas and the hydrogen gas compressed by the fourth step, by passing through a pressure swing adsorption system from through the fourth conduit, the concentration of which carbon monoxide gas and hydrogen gas A carburizing gas production method comprising: obtaining a carburizing gas having a carbon monoxide gas concentration in the range of 30 to 60 mol%. The first step is, prior to the heating of the natural gas by the first heater, mixed with hydrogen gas to the natural gas, the mixed gas is heated by the first heater, and passed to the desulfurizer above The gas production method for carburizing treatment according to claim 1, wherein the method is a step of sending to the first pipeline . The second step is a step of mixing carbon dioxide gas with the oxygen gas prior to heating of the oxygen gas by the second heater, heating the mixed gas with the second heater, and sending the mixed gas to the second conduit. The method for producing a carburizing gas according to claim 2. The carburizing gas according to claim 2 or 3, wherein the fifth step is a step of mixing nitrogen gas into the gas containing carbon monoxide gas and hydrogen gas whose concentration is increased by the pressure swing adsorption device. Production method. The gas production method for carburizing treatment according to claim 2 or 3, further comprising a step of mixing carbon monoxide gas with the gas containing carbon monoxide gas and hydrogen gas obtained in the fifth step.   The gas production method for carburizing treatment according to any one of claims 1 to 5, wherein a concentration ratio of carbon monoxide gas to hydrogen gas in the carburizing treatment gas is set to 1: 1. A carburizing treatment gas production facilities used in the claim 1 carburizing gas production method according a first heater for heating the natural gas, a desulfurizer for desulfurizing the heated natural gas, in this desulfurizer A first pipe for passing desulfurized natural gas; a second heater for heating oxygen gas; a second pipe for passing oxygen gas heated by the second heater and connected to the first pipe; Carbon monoxide gas from a mixed gas of natural gas desulfurized by the desulfurizer and sent through the first pipe and oxygen gas heated by the second heater and sent through the second pipe A reformer for generating a gas containing hydrogen gas, a third pipe for passing the produced gas containing the carbon monoxide gas and the hydrogen gas produced by the reformer, and the third pipe A cooler that passes the product gas sent through the A gas-liquid separator that gas-liquid separates the partly liquefied product gas, a drain line that drains the liquid after the gas-liquid separation to the outside of the gas-liquid separator, and the gas-liquid separation a compressor suction holder through a gas containing the above-described carbon monoxide gas and the hydrogen gas after a compressor for compressing the gas having passed through the compressor suction holder, the gas compressed in the compressor A carburizing gas production facility comprising a fourth pipe passing therethrough and a pressure swing adsorption device through which the gas sent through the fourth pipe passes .   A carburizing gas production facility for use in the carburizing gas production method according to claim 2, wherein a hydrogen gas pipe is connected to the natural gas pipe upstream of the first heater. The gas production facility for carburizing treatment according to claim 7, wherein the connecting pipe line is connected to the first heater.   A carburizing gas production facility for use in the carburizing gas production method according to claim 3, wherein the carbon dioxide gas pipe is connected to the oxygen gas pipe upstream of the second heater. The carburizing gas production facility according to claim 8, further comprising a passage, the connecting pipe of which is connected to the second heater. A carburizing treatment gas production facilities used in the claim 4 carburizing gas production method according to the pipe of the gas containing the downstream of the pressure swing adsorption unit and a carbon monoxide gas and hydrogen gas, The gas production facility for carburizing treatment according to claim 8 or 9, wherein a liquid nitrogen tank is connected. A carburizing treatment gas production facility used for the carburizing treatment gas producing method of the fifth aspect, the conduit of the gas containing the downstream of the pressure swing adsorption unit and a carbon monoxide gas and hydrogen gas, The carburizing gas production facility according to claim 8 or 9, wherein a carbon monoxide gas container is connected.

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