JP2008214163A - Combustible gas mixing method and mixer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustible gas mixing method and a combustible gas mixer by which a mixed gas for reforming can be produced by uniformly mixing a high-pressure and high-temperature combustible gas with an oxygen-containing gas without inducing abnormal combustion such as backfire and spontaneous fire. <P>SOLUTION: The combustible gas mixing method comprises mixing a combustible raw material gas with an oxygen-containing gas to produce a premixed gas in a combustible concentration range, wherein a plurality of mixing stages 1-3 are disposed, and the concentration of the raw material gas component in a mixed gas produced in each mixing stage is varied so that the combustible concentration range is attained in the final mixing stage, whereby the objective premixed gas is produced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a combustible gas mixing method and a mixer suitable for use in a reactor or the like of a synthesis gas production plant.

  To make effective use of natural gas, once natural gas is converted into highly reactive synthesis gas (for example, methane is converted to carbon monoxide and hydrogen), the molecular structure is rearranged by FT synthesis (Fischer-Tropsch synthesis), etc. GTL (gas to liquid) conversion technology for producing liquid fuels such as light oil, kerosene, or DME (dimethyl ether) is being actively researched. This GTL technology liquefies gaseous natural gas and makes it easier to transport and handle, as well as harmful components such as sulfur components in fuel, carbon monoxide and nitrogen oxides in exhaust gas compared to petroleum-derived products. It is attracting attention as a technique for obtaining fuel that can reduce substances and have a low environmental impact.

  In order to popularize GTL technology, it is required to develop a synthesis gas production plant that is highly efficient and suitable for business. Conventionally, the ATR method (Auto Thermal Reforming Method) is known as one of the synthesis gas production methods. The ATR method causes an exothermic reaction by burning part of a synthetic gas raw material (methane gas, etc.) such as natural gas, petroleum, coal, biomass, etc. with an oxygen burner, and then high-temperature steam or carbon dioxide produced by the previous reaction. A gas is used to reform a methane gas or the like by an endothermic reforming reaction in a catalyst layer to generate a synthesis gas.

  This ATR method has a problem in that a large amount of soot is generated because a part of the raw material gas is reacted with oxygen, so that it is burned in an excessive fuel (fuel rich) state as a whole. In addition, if a large reactor is used to generate synthesis gas on a large scale, it will be necessary to install multiple oxygen burners in the reactor, but there will be no development of multiple burners that can be safely operated without burning. Difficult, this becomes a bottleneck, making it difficult to increase the size of the reactor. Instead of increasing the size with multiple oxygen burners, increasing the number of reactors to solve the problem of large-scale production increases the equipment cost, and also makes it possible to operate many reactors safely and smoothly. However, there is a problem, and a problem to be solved arises in terms of plant operability.

  As another method for producing synthesis gas, a CPO method (Catalytic Partial Oxidation method) is known. In the CPO method, a premixed gas in which an oxygen-containing gas is premixed with a raw material gas (methane, etc.) is pressurized and heated to about 4 MPaG, 300 degC to lead to the catalyst layer in the reactor, and a part of the premixed gas As a heat source for the subsequent reforming reaction (endothermic reaction), synthesis gas (carbon monoxide and hydrogen) is generated. In other words, the CPO method is safer than the ATR method because the ATR method maintains the high temperature state by the partial oxidation reaction by the catalyst in the reactor, unlike the ATR method in which the raw material gas is exposed to high temperature at once by the oxidation reaction by the burner. It can be said that it is a synthesis gas production method that can be operated continuously, and a partial oxidation reaction and a reforming reaction are allowed to proceed simultaneously at the subsequent stage to enable continuous operation.

  The CPO method is different from the cyclic hydrocarbon reforming method described in Patent Document 1 in that it is a synthesis gas production method that can be operated continuously in one reactor. The reforming method of Patent Literature 1 includes a pair of reactors that can perform a reforming step and a regeneration step, a step of reacting a hydrocarbon fuel and water vapor to generate a hydrogen-containing gas, and a regeneration gas. As a result of catalytic combustion, the regeneration step of raising the catalyst temperature decreased in the reforming step is repeated alternately. In other words, in the cycle type hydrocarbon reforming method, while one reactor is performing the reforming step, the other reactor performs the regeneration step, so that the hydrocarbon reforming is performed in a cycle type (batch type). However, the hydrogen-containing gas is continuously produced. Such a cyclic hydrocarbon reforming method is not suitable for large-scale gas production because the synthesis gas production efficiency is poor.

In the CPO method, it is considered that the partial oxidation reaction proceeds with the aid of the catalyst as described above. However, without the aid of the catalyst in the space in the catalyst layer (by non-catalytic reaction) ) Combustion reaction (partial oxidation reaction), reforming reaction, and water shift reaction are also considered to occur. In any case, unlike the ATR method, the CPO method does not require a burner, so that the reactor can be enlarged in this respect. Increasing the size of the reactor reduces equipment costs and greatly contributes to improvement of plant operability.
JP 2006-282470 A

  When the synthesis gas is generated by the CPO method, if the raw material gas (methane, etc.) and the oxygen-containing gas (especially oxygen gas) are not uniformly mixed and supplied to the reaction zone, the temperature rise in the reaction zone will be biased. A part of the catalyst layer becomes abnormally high in temperature, causing problems such as burning. In order to prevent overheating due to uneven concentration of the air-fuel mixture, the raw material gas (such as methane) and the oxygen-containing gas are mixed in advance in advance, and such a premixed gas is supplied to the reaction zone in the reactor. Well, the overheating problem as described above is eliminated. However, the premixed gas in this case needs to be pressurized and heated to about 4 MPaG and about 300 degC in the above-described synthesis gas production by the CPO method.

  Oxygen in the pressurized and heated premixed gas has a strong combustion support, so it is necessary to avoid mixing oxygen with the fuel in advance and to mix it in the reaction zone (reaction field) as much as possible. It is considered. This is because unexpected combustion due to self-ignition or backfire from the catalyst layer does not occur during mixing. Mixing in the reaction zone means supplying an air-fuel mixture having a non-uniform fuel concentration to the reaction zone. Once combustion occurs during the mixing of combustible gas, depending on the mixed gas conditions, the pressure in the system containing the reactor suddenly rises, so-called a very dangerous detonation state There is a risk of doing.

  Therefore, in a synthesis gas production plant based on the CPO method, a high-pressure and high-temperature uniform premixed gas is necessary. However, such a premixed gas has a two-way conflicting problem that involves the risk of spontaneous ignition and flashback. In order to operate a synthesis gas production plant safely and stably over a long period of time, a mixer that solves the above-described problems is required, and such a mixer is provided. For the first time, the manufacturing equipment can be enlarged.

  The cycle-type hydrocarbon reformer disclosed in Patent Document 1 described above is provided with a regeneration gas mixer independent of the reactor, and the mixer is configured to supply a regeneration gas and an oxygen-containing gas. Mixing is performed, and a uniform gas mixture for regeneration is supplied to the reactor for performing the regeneration step. By providing a mixer, at the initial stage of switching to the regeneration process, it is possible to prevent a portion where the catalytic combustion temperature locally rises in the reactor due to non-uniformity of the mixed gas for regeneration. In addition, it is possible to prevent the occurrence of self-ignition and gas phase combustion of the regeneration gas that accompanies or approach the local high temperature part.

  The regeneration gas mixer disclosed in Patent Document 1 has the same object as that of the present invention in that a mixed gas in which a combustion gas and an oxygen-containing gas are uniformly mixed must be supplied into the reactor. The mixer of Patent Document 1 is provided with a regeneration gas and an oxygen-containing gas separately prepared for catalyst regeneration only for the purpose of regenerating the catalyst capacity by raising the temperature of the catalyst whose temperature has been lowered by the reforming reaction. The homogeneous mixed gas may be generated.

  On the other hand, in a large-scale synthesis gas production plant using the CPO method, the premixed gas supplied to the catalyst layer in the reactor must be pressurized and heated to about 4 MPaG and about 300 degC. It is a raw material gas for a reforming reaction, and a raw material gas for a partial oxidation reaction that supplies a heat source for the reforming reaction (endothermic reaction). As a mixer for generating such a premixed gas, a mixer having a simple configuration as disclosed in Patent Document 1 cannot be applied.

In addition to natural gas, the present invention is not limited to natural gas, but also oxygen-containing gas containing steam, CO2, CO, etc. in addition to synthetic gas raw materials (combustible gas) such as petroleum, coal, biomass, and oxygen (combustible gas component). It can be widely applied as a mixer used for mixing with.
The present invention has been proposed in order to solve the above two conflicting problems, and the generated high-pressure and high-temperature premixed gas is not induced without causing abnormal combustion such as flashback or self-ignition. For example, an object of the present invention is to provide a combustible gas mixing method and a combustible gas mixer that can be suitably used as a reformed mixed gas in a large reactor or the like.

According to the flammable gas mixing method of generating a premixed gas in the flammable concentration range by mixing the flammable source gas and the oxygen-containing gas according to the present invention of claim 1, a plurality of mixing stages are provided, The raw gas component concentration in the mixed gas generated in the mixing stage is changed, and the premixed gas is generated by reaching the combustible concentration range in the final mixing stage.
As a method of reaching the combustible concentration range in the final mixing stage, the oxygen-containing gas prepared in each downstream mixing stage is sequentially added to the combustible raw material gas that is on the rich side and out of the combustible concentration range. It may be a method of mixing and reaching the flammable concentration range in the final mixing stage (Claim 2), or downstream to the flammable source gas having a flammable source gas concentration on the lean side and out of the flammable concentration range. Alternatively, the combustible raw material gas prepared in each mixing stage may be mixed, and the combustible concentration range may be reached in the final mixing stage (Claim 3).

  According to the combustible gas mixer that generates a premixed gas in the combustible concentration range by mixing the combustible raw material gas and the oxygen-containing gas according to the present invention of claim 4, the combustible is added to the mixing stage in the mixer. A gas nozzle that supplies a source gas and an oxygen-containing gas to form a gas jet, and a position downstream of the gas nozzle and around the axis of the gas jet from the upstream, the combustible source gas and oxygen-containing A plurality of swirling and mixing means disposed at each of a plurality of mixing stage positions for forming a swirling flow of one of the other gases, mixing the swirling flow and a gas jet from the upstream, and jetting them downstream. The gas component concentration in the mixed gas generated at each mixing stage position is changed to generate a premixed gas that reaches the combustible concentration range at the final mixing stage position. To.

According to the present invention of claim 5, each of the gas nozzle and the swirl mixing means is attached to a partition plate that partitions the mixing stage, and the gas nozzle and swirl mixing means of each partition plate are stacked coaxially to form a mixer unit. Is formed.
According to a sixth aspect of the present invention, the same number of gas nozzles and swirl mixing means of each partition plate are attached to the corresponding positions, and the gas nozzles and swirl mixing means of each partition plate are coaxially stacked. Thus, a plurality of mixer units are formed.

According to the seventh aspect of the present invention, the swirling and mixing means includes a swirler having a plurality of swirling blades arranged in the circumferential direction, and a guide duct for guiding the swirling flow flowing out of the swirling blades to the mixing stage. It is characterized by providing.
According to the present invention of claim 8, the partition plates are stacked using the swirler as a spacer.

  According to the invention of claim 1, if the combustible raw material gas and the oxygen-containing gas used in the reforming process and the like are mixed at once, a uniform air-fuel mixture is not immediately produced. There is a risk that an air-fuel mixture having a concentration easily combusted may be formed. Therefore, since there is a risk of entering the combustible concentration range, a plurality of mixing stages for mixing the combustible raw material gas and the oxygen-containing gas are provided, and the raw material gas component concentration in the mixed gas generated at each mixing stage is stepwise. By gradually changing, the mixing region that falls within the flammable concentration range locally is minimized, and the desired flammable concentration range region is reached in the final mixing stage, whereby the premixed gas can be generated safely.

  Needless to say, the final stage of mixing is preferably set immediately before the process of supplying the premixed gas, such as a reforming process. The desired combustible concentration of the mixed gas to be reached in the final mixing stage should be set to a concentration that does not cause self-ignition or flashback under the use atmosphere conditions of the mixed gas, but the combustible raw material gas and oxygen supplied to the mixer Even if each concentration value of the contained gas deviates from the target set value and conditions that can cause spontaneous ignition or flashback are observed locally in the final mixing stage, the concentration of the mixed gas is determined to be self-ignited in the upstream mixing stage. It is possible to set a concentration range that is sufficiently deviated from a combustible concentration range that can prevent backfire, and to effectively prevent propagation of the generated flame.

  In many processes, such as natural gas and methane reforming processes, the combustible feed gas that is usually on the fuel rich side and out of the flammable concentration range, contains oxygen prepared at each downstream mixing stage. It is desirable to mix the gases sequentially and reach the desired combustible concentration range in the final stage of mixing (Claim 2). However, depending on the process, the combustible raw material gas concentration is on the fuel lean side and out of the combustible concentration range. It may be preferable to mix the combustible raw material gas prepared in each downstream mixing stage with the oxygen-containing gas and reach the desired combustible concentration range in the final mixing stage (Claim 3). The mixing method can be selected.

The combustible gas mixing method of the present invention according to claims 1 to 3 is implemented by a combustible gas mixer according to claim 4 or less.
According to the combustible gas mixer of the present invention of claim 4, a strong mixing shear layer is formed between the gas jet formed by the gas nozzle and the swirl flow formed by the swirl mixing means in each downstream mixing stage. A uniform mixed gas can be generated at each mixing stage. And the gas component density | concentration in the mixed gas produced | generated in each mixing stage position can be changed sequentially, and the premixed gas which reached the desired desired combustible concentration range area in the final mixing stage position can be obtained.

  If the ratio of the combustible raw material gas and oxygen-containing gas used in the process is on the fuel rich side, the combustible raw material gas is jetted by the gas nozzle, and the oxygen-containing gas is supplied coaxially to the outside of the jet, and the combustible raw material gas and If the ratio of oxygen-containing gas is on the lean side of the fuel, the oxygen-containing gas is ejected by the gas nozzle, and if the combustible raw material gas is supplied coaxially to the outside of the jet, the mixer will always be mixed in a state that is difficult to burn. As a result, an air-fuel mixture that finally falls within the combustible concentration range can be safely generated.

  According to the present invention of claim 5, since the gas nozzles and swirl mixing means of each partition plate are stacked on the same axis to form a mixer cell unit, each of the gas nozzles and swirl mixing means attached to the mixer By simply stacking the partition plates, the mixer can be assembled, and when a plurality of gas nozzles and swirl mixing means are attached to each partition plate as in the present invention of claim 6, the number of mixer cell units can be increased as required. Even if the capacity of the mixer is increased in response to an increase in the size of a process apparatus such as a synthesis gas production plant, it is possible to supply a premixed gas with a uniform concentration, resulting in a large process apparatus. Can be realized.

  According to the seventh aspect of the present invention, the swirl mixing means is constituted by a swirler, and the swirl flow flowing out from the swirl vanes is guided to the mixing stage by the guide duct and mixed with the gas jet from the upstream. In addition, according to the present invention of claim 8, the partition plates are stacked using the swirler as a spacer, so that the assembly of the combustible gas mixer becomes extremely easy.

Hereinafter, embodiments of a combustible gas mixing method and a combustible gas mixer according to the present invention will be described with reference to the drawings.
First, with reference to FIG. 1, a synthesis gas production process by the CPO method that uses the combustible gas mixing method and the mixer according to the present invention and is suitable will be described. In the manufacturing process shown in FIG. 1, a process for synthesizing hydrogen gas from methane, which is a main fuel component in natural gas, is shown in order to facilitate understanding and simplify the description.

  A catalyst layer (reaction zone) 2 is mounted in the high-pressure reactor 1 that synthesizes hydrogen gas. In this catalyst layer 2, hydrogen gas is subjected to partial oxidation reaction, reforming reaction, and aqueous shift reaction, which will be described later. Is produced as a main component. A combustible gas mixer 10 according to the present invention is provided immediately upstream of the catalyst layer 2 in the reactor 1. The reactor 1 is supplied with methane gas (CH4), which is a combustible raw material gas, and an oxygen-containing gas composed of oxygen (O2) and water vapor (H2O). These supply gases are mixed by a method described in detail later. The mixture is uniformly mixed in the vessel 10 and supplied to the catalyst layer 2 described above.

  The component ratio of methane gas (CH4), oxygen (O2) and water vapor (H2O) supplied to the reactor 1 and the pressure and temperature of the supply gas should be set to appropriate values depending on the synthesis gas component ratio to be obtained. However, if these supply gas setting conditions change, the catalyst layer temperature in the reactor 1 also changes greatly. Therefore, these supply gas setting conditions are set in consideration of the durability and safety of the reactor and the like. The

  FIG. 1 illustrates supply gas setting conditions. The supply gas component ratio is adjusted to, for example, 10: 6: 6 at the time of supply to the catalyst layer 2, and the supply gas pressure and temperature are set to 4 MPaG, for example. If each is set to 300 degC, depending on the catalyst, the upstream catalyst layer temperature of the catalyst layer 2 is maintained at about 850 degC, the downstream catalyst layer temperature after reforming is about 700 degC, and hydrogen (H2) and carbon monoxide ( CO) synthesis gas is expected to be obtained at a component ratio of 2: 1. In order to secure the reaction rate (catalyst temperature) in the catalyst layer 2 and to set the reforming reaction temperature, the supply gas pressure and temperature are increased to high pressure and high temperature as described above by a compressor and a heat exchanger (not shown). It is set.

When the premixed gas of the combustible raw material gas (methane gas) and the oxygen-containing gas (oxygen and water vapor) whose supply gas component ratio, gas pressure, temperature, etc. are adjusted as described above is supplied to the catalyst layer 2, the reaction formula 1 and It is considered that an oxidation reaction and a partial oxidation reaction (both exothermic reactions) indicated by 2 occur, and a reforming reaction (endothermic reaction) indicated by reaction formulas 3 to 5 occurs simultaneously.
CH4 + 2O2 = CO2 + 2H2O + 891 kJ (Scheme 1)
CH4 + 1 / 2O2 = CO + 2H2 + 36 kJ (Scheme 2)
CH4 + H2O = CO + 3H2-250kJ (Scheme 3)
CH4 + CO2 = 2CO + 2H2-247 kJ (Scheme 4)
CO + H2O = CO2 + H2-3kJ (Scheme 5)
In the synthesis gas production method by the CPO method, the oxygen component ratio in the supply gas is lower than that in the ATR method, and the oxidation reaction performed in the catalyst layer 2 is mainly the partial oxidation reaction shown in the reaction formula 2. The oxidation reaction of methane and oxygen shown in Reaction Formula 1 is also partly performed. Then, the reforming reaction of reaction formula 3 having a large endothermic amount is simultaneously performed, and the reforming reaction and the aqueous shift reaction shown in reaction formulas 4 and 5 are also partially performed.

The partial oxidation reaction and the oxidation reaction continue until all the oxygen in the supply gas is consumed. However, as described above, the partial oxidation reaction shown in the reaction formula 2 and the reaction formula 3 are performed because the oxygen content in the supply gas is small. The reforming reaction shown by (1) is dominantly performed, and the catalyst layer temperature rises to 850 degC at most.
When all the oxygen components are consumed and the partial oxidation reaction or the oxidation reaction is completed, the reforming reaction (aqueous shift reaction) of reaction formulas 3 to 5 becomes dominant thereafter. Since all of these reactions are endothermic reactions, the catalyst temperature decreases as it goes to the downstream portion of the catalyst layer 2, and becomes approximately 700 degC at the catalyst outlet. Under the supply gas setting conditions as described above, synthesis gas of hydrogen (H2) and carbon monoxide (CO) is obtained at a component ratio of 2: 1.

  When the amount of oxygen in the oxygen-containing gas is increased, the oxidation reaction of Reaction Formula 1 becomes dominant, so the catalyst temperature rises and the reforming reaction (Formulas 3, 4, and 5) that is an endothermic reaction becomes active. The yield of hydrogen will increase. However, when the amount of oxygen in the oxygen-containing gas is increased, according to the prior art, there is a problem in the durability and catalyst life of the manufacturing plant, particularly the reactor, but the combustible gas mixer of the present invention will be described in detail later. As described above, the uniform premixed gas can be supplied to the catalyst layer 2 and partial (local) overheating of the catalyst can be prevented, so that the mixed gas obtained in the mixer 10 according to the present invention can be prevented. Although depending on the mixing characteristics (such as the degree of uniform mixing), the catalyst temperature can be increased within the achievable limit, and the synthesis gas can be produced efficiently.

FIG. 2 is a conceptual diagram for explaining a method of mixing combustible gas by the mixer 10 according to the present invention. For example, a combustible raw material gas (fuel) such as methane and an oxygen-containing gas composed of oxygen and water vapor are used. The mixing method which produces | generates the premixed gas in a combustible concentration range area by mixing is shown.
In order to generate the premixed gas, first, the fuel gas is ejected from the gas nozzle 12 toward the mixing field (mixing stage), and the oxygen-containing gas is uniformly mixed with the gas jet ejected from the nozzle 12. In the present invention, in order to uniformly mix these gases, the fuel gas and the oxygen-containing gas are not mixed at once, but a plurality of mixing stages are provided, and the oxygen content is gradually increased at each stage. A mixed gas is generated, and a fuel gas and an oxygen-containing gas are mixed so as to become a premixed gas having a desired oxygen content in a final mixing stage.

  Specifically, a mixing stage 1 to 3 is provided at a downstream position of the gas nozzle 12 to sequentially mix the oxygen-containing gas into the gas jet from the upstream, and the oxygen-containing gas is supplied to the mixing stages 1 to 3. Ducts 14 to 16 are disposed. These guide ducts 14 to 16 are sequentially arranged with their respective axes aligned with the axis of the gas nozzle 12. For example, three types of oxygen-containing gases 1 to 3 are prepared, and the guide ducts 14 to 16 guide the oxygen-containing gases 1 to 3 to the corresponding mixing stages 1 to 3, respectively.

  The mixing stage 1 is formed between the nozzle hole position p1 of the gas nozzle 12 and the outlet opening position p2 of the guide duct 14, and is a mixed region where the gas jet from the gas nozzle 12 and the oxygen-containing gas 1 are mixed to generate the gas mixture 1. Corresponds. Similarly, the mixing stage 2 is formed between the outlet opening position p2 of the guide duct 14 and the outlet opening position p3 of the guide duct 16, and the gas jet of the air-fuel mixture 1 ejected from the outlet opening of the duct 14 and the oxygen-containing gas 2 The mixing stage 3 is formed between the outlet opening position p3 of the guide duct 16 and the outlet opening position p4 of the guide duct 18, and the outlet opening of the duct 16 is mixed. Corresponds to a mixed region in which the gas jet of the gas mixture 2 ejected from the gas and the oxygen-containing gas 3 are mixed to generate the gas mixture 3.

  Since the fuel gas (methane) from the gas nozzle 12 is not yet mixed with the oxygen-containing gas 1 at the nozzle nozzle position p1, the fuel concentration ratio is a value 1 (100%) as shown in FIG. ). The combustible area shown in the figure (the area shown by diagonal lines) contains oxygen (O2) and water vapor (H2O) as components in fuel gas (methane) pressurized and heated to 4.0 MPaG and 300 degC. This shows the methane concentration region where the premixed gas is ignited and flame propagation is possible when gas is mixed, the methane concentration in the mixed gas is decreased, and the oxygen concentration is increased to generate the premixed gas. .

  Before the oxygen-containing gas 1 is supplied to the mixing stage 1, the contained oxygen and water vapor are sufficiently uniformly mixed, and even when mixed with the fuel gas when supplied to the mixing stage 1, the combustible range A mixed gas having a concentration value in the region is not generated locally. Then, by the time when the fuel gas and the oxygen-containing gas 1 supplied to the mixing stage 1 reach the outlet opening position p2, the gas is sufficiently stirred and mixed in the stage 1 to generate the air-fuel mixture 1 having a uniform fuel concentration. Is done. The air-fuel mixture generated in the mixing stage 1 has a combustible raw material gas component concentration that changes toward the concentration in the combustible range region, but is a value far from the combustible range region in the vicinity of the outlet opening position p2 of the guide duct 14. Stay on.

  As with the oxygen-containing gas 1, the oxygen-containing gas 2 is sufficiently homogeneously mixed with the oxygen and water vapor until the oxygen-containing gas 2 is supplied to the mixing stage 2, and the gas 2 is stirred and mixed uniformly. Even if the gas 1 comes out in the mixing stage 2 and mixes, the air-fuel mixture in the combustible concentration range is not generated locally. In the vicinity of the outlet opening position p3 of the duct 16, a concentration value closer to the combustible range region than the fuel concentration at the position p2 is shown, but the concentration value stays away from the combustible range region, and a safe side air-fuel mixture is generated. In the mixing stage 2 as well, the fuel gas and the oxygen-containing gas 2 are sufficiently agitated and mixed to generate the air-fuel mixture 2 having a uniform fuel concentration.

The mixing stage 3 is a final mixing stage in which the oxygen-containing gas 3 is added to the air-fuel mixture 2 to generate the air-fuel mixture 3 having a target concentration value in the combustible range region. Oxygen that also contains the oxygen-containing gas 3 and water vapor are sufficiently uniformly mixed, and by sequentially mixing with the mixture 2, the mixture 3 having a uniform fuel concentration is generated.
At the outlet opening position p4 of the duct 18, an air-fuel mixture 3 having a fuel concentration within the combustible range is generated. The mixing stage 3 is desirably disposed as close as possible to the catalyst layer 2 disposed in the downstream. The period during which the premixed gas stays in the combustible region is preferably set short.

  Since the air-fuel mixture 3 according to the present invention is produced by mixing the air-fuel mixture and the oxygen-containing gas 3 that are sequentially and uniformly mixed in the preceding stages, a pre-air-fuel mixture with little local concentration unevenness is generated. By setting the period in which the air-fuel mixture 3 generated in the mixing stage 3 stays in the combustible region as short as possible, not only the above-mentioned self-ignition but also the back-fire can be prevented. Is possible.

  In order to obtain uniform mixing in each of the mixing stages 1 to 3, it is preferable to generate a shear layer at the boundary between the two flows to be mixed and promote mixing by turbulent flow having a small scale. Such a mixing promotion method generally gives a relative velocity difference between the two flows, and various methods such as a method of mixing by causing the jets to collide against each other, a method of mixing by a stack mixer, and the like can be considered. Although it does not specifically limit, as shown in FIG. 3, the method of giving swirl to a flow using a swirler (swirl mixing means, swivel imparting means) is suitable.

  FIG. 3 exemplifies a method of imparting swirl to each of the fuel gas, the air-fuel mixture 1 and the air-fuel mixture 2 supplied to each mixing stage. The gas nozzle 12 is provided with a swirler (swivel imparting means) 12a that gives a swirl velocity component around the axis in addition to the axial velocity component to the gas jet, and the fuel gas jet exiting the swirler 12a meets the mixing stage 1 The mixing shear layer is formed at the mixing boundary with the oxygen-containing gas 1 to promote mixing. A swirler 14 a is attached to the outlet position p 2 of the duct 14 upstream of the mixing stage 2, and swirls the gas jet of the air-fuel mixture 1, and the outlet position p 3 of the duct 16 upstream of the mixing stage 3. The swirler 16a is attached to the gas jet flow of the air-fuel mixture 2, and each swirler (swivel imparting means) 14a, 16a promotes mixing on each stage.

  A swirler that swirls the gas flow may also be provided at the outlet position p4 of the duct 18. The swirler 18a causes the air-fuel mixture 3 ejected from the mixing stage 3 to be radially outward with respect to the axial flow. Has the effect of diffusing. In addition to the swirlers 12a, 14a, 16a, or instead of these swirlers, swirlers (swirl mixing means) may be provided upstream of the guide ducts 14, 16, 18 and two gases from these swirlers may be provided. Setting the flow swirl directions to be opposite to each other is effective for promoting mixing in the shear layer.

In the above-described embodiment, three mixing stages are provided to generate the premixed gas 3. However, a larger number of mixing stages may be provided to sequentially generate a finely and uniformly uniform mixture. . In any case, in the present invention, at least two mixing stages are necessary.
The oxygen-containing gases 1 to 3 may use the same gas components (oxygen and water vapor), or may use oxygen-containing gases composed of mutually different components. Further, instead of the oxygen-containing gas 1 in the above embodiment, only the water vapor is supplied to the mixing stage 1 and the supply start stage of the oxygen-containing gas may be started from the mixing stage 2 in the above embodiment shown in FIGS. Good.

In addition to methane, the combustible raw material gas may contain a combustible gas such as CO or ethane, and may contain other gas components such as CO2 and nitrogen. Similarly, the oxygen-containing gas may of course contain gas components such as CO 2 and nitrogen in addition to oxygen and water vapor.
In the above embodiment, the combustible raw material gas is ejected to the gas nozzle 12 and the oxygen-containing gas supplied from the guide duct is mixed from the outer periphery of the gas jet or from the outer periphery to the gas jet of the mixed gas generated downstream. On the contrary, an oxygen-containing gas is jetted and supplied from the gas nozzle 12, and a combustible raw material gas diluted with water vapor or the like is sequentially supplied from the outer periphery of the gas jet into a plurality of mixing stages, and the raw material gas component in the mixed gas is supplied. The concentration may be changed to reach the combustible concentration range in the final mixing stage. In this case, the fuel concentration of the air-fuel mixture that is sequentially generated is changed from the fuel lean side to the rich side and reaches the combustible concentration range in the final mixing stage to generate the premixed gas.

  4 and 5 show an embodiment of the mixer 10 incorporated in the reactor 1 shown in FIG. The mixer 10 is disposed immediately upstream of the catalyst layer 2 in the reactor 1, and the mixer 10 has a number of mixer cell units 10A corresponding to the increase in size of the reactor. In other words, the mixer 10 includes partition plates 20a to 20d that partition each of the plurality of mixing stages, a gas nozzle 22 that is attached to each partition plate and supplies a combustible raw material gas (methane), and a gas jet from the gas nozzle 22 or each It comprises a large number of mixer cell units 10A comprising swirl mixing means 24, 26, and 28 for supplying oxygen-containing gas to the outer periphery of the gas jet of the mixed gas generated in the mixing stage.

  The configuration of each mixer cell unit 10A will be described in detail with reference to FIG. 5. Partition plates 20a and 20b that partition the mixing stage 1 are arranged in the reactor 1 in parallel at a predetermined interval. Established. Similarly, the partition plates 20b and 20c that partition the mixing stage 2 and the partition plates 20c and 20d that partition the mixing stage 3 are arranged in the reactor 1 in parallel with a predetermined distance therebetween. Each of the partition plates 20 a to 20 d accommodated in the reactor 1 has a substantially disk shape so as to match the internal shape of the reactor 1. A supply passage for oxygen-containing gases 1 to 3 is formed between the partition plates 20a and 20b, 20b and 20c, and 20c and 20d, respectively, and these oxygen-containing gases 1 to 3 are supplied from a supply port (not shown). Is supplied to each passage. A combustible raw material gas (methane) pressurized and heated to a predetermined pressure and temperature is supplied to the chamber space facing the upstream side surface of the partition plate 20a located on the most upstream side via the fuel supply port 1a of the reactor. Is done.

  A gas nozzle 22 is attached to the partition plate 20a. The nozzle 22 has a trumpet shape that expands toward the upstream side, and its downstream end 22a opens toward the mixing stage 1 and is welded to the plate 20a. Since the nozzle 22 expands in a trumpet shape toward the flow of the combustible raw material gas, the combustible raw material gas can be introduced into the nozzle 22 and smoothly guided to the mixing stage 1.

  A swirler device (swivel mixing means) 24 is attached to the partition plate 20 b at a position corresponding to the attachment of the gas nozzle 22 and coaxially with the nozzle 22. The swirler device 24 is for supplying a swirl component to the combustible gas 1 while supplying it to the mixing stage 1. The swirler device 24 has a large number of swirling blades in the circumferential direction and is mixed in the mixing stage 1. Is formed as a gas jet, and the opening 24a is projected toward the downstream mixing stage 2, and a guide duct 24b that is slightly reduced in diameter is attached to the nozzle 24. Thus, the gas jet can be smoothly guided and supplied to the mixing stage 2.

  A swirler device (swirl mixing means) 26 is attached to the partition plate 20c coaxially with the attachment positions of the gas nozzle 22 and the swirler device 24. Similarly to the swirler device 24, the swirl component is added to the combustible gas 2. Is provided to the mixing stage 2 while having a large number of swirl vanes in the circumferential direction, and the mixture 2 mixed in the mixing stage 2 is ejected downstream as a gas jet. An opening 26a is formed, and a guide duct 26b similar to the guide duct 24b is attached to the opening 26a so that the gas jet can be smoothly guided and supplied to the mixing stage 3.

Similarly, a swirler device 28 is attached to the partition plate 20d, a guide duct 28b is attached to the opening 28a, and the premixed gas from the mixing stage 3 is diffused and supplied to the inlet end face of the catalyst layer 2 as a gas jet. Yes.
In addition, since the fuel gas and the oxygen-containing gas are sequentially mixed at substantially constant pressure and temperature in the mixing stages 1 to 3, the volume of the generated air-fuel mixture sequentially increases, and accordingly, the swirler devices 24, 26, and 28 are accordingly increased. In addition, the guide ducts 24b, 26b, 28b and the like have large shapes.

  Thus, the mixer cell unit 10A is formed by coaxially stacking the gas nozzles and swirler devices of each partition plate. The mixed gases 1 to 3 generated in the mixing stages 1 to 3 of the mixer cell unit 10A change the fuel concentration in the same manner as described with reference to FIGS. A premixed gas having a uniform fuel concentration can be generated by reaching the combustible range.

  In a large synthesis gas production plant, it is difficult to generate a uniform premixed gas upstream of the catalyst layer 2 with one mixer, and the required number of mixers according to the projected area of the entrance of the catalyst layer 2 It is necessary to arrange the cell unit 10A. By disposing a large number of units 10A as in the mixer 10 of the present invention, uniform premixed gas can be easily supplied over the entire area of the catalyst inlet end face, and local overheating of the catalyst layer 2 can be prevented. Can be prevented.

  In addition, the mixer according to the present invention only needs to align the axis of the mixer cell unit 10A arranged on the partition plate, and the swirler device can be connected to the spacer only by uniforming the height of each swirler device. Thus, the partition plates can be stacked at a predetermined interval, and the mixer 10 can be assembled very easily.

Outline of reactor structure for syngas production to which a combustible gas mixing method and a combustible gas mixer according to the present invention are preferably applied, and a flow for explaining an oxidation / reforming reaction occurring in the reactor The graph which shows the figure and the temperature change in a reactor correspondingly shown. 2 shows a combustible gas mixing procedure by the combustible gas mixing method according to the present invention, FIG. 2 (a) is a conceptual diagram for showing gas mixed in each mixing stage, and FIG. 2 (b) is the same mixing procedure. The graph explaining the fuel density | concentration change in each mixing stage in contrast with. The conceptual diagram for illustrating a uniform mixing method with the swirler to which the combustible gas mixing method and combustible gas mixer which concern on this invention are applied suitably. FIG. 2 is a partially cut perspective view showing a configuration in the reactor 1 shown in FIG. 1. The fragmentary sectional view for showing the structure of 10 A of mixer cell units which comprise the mixer 10 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reactor 2 Catalyst 10 Mixer 10A Mixer cell unit 12 Gas nozzles 14, 16, 18 Guide ducts 12a, 14a, 16a, 18a Swirler (swivel imparting means)
22 Gas nozzle 24, 26, 28 Swirler device (swirl mixing means)

Claims (8)

  A mixing method for generating a premixed gas in a combustible concentration range by mixing a combustible raw material gas and an oxygen-containing gas, wherein a plurality of mixing stages are provided, and the raw material gas in the mixed gas generated at each mixing stage A combustible gas mixing method characterized by generating a premixed gas that changes the component concentration and reaches the combustible concentration range in the final mixing stage.   The oxygen-containing gas prepared in each downstream mixing stage is mixed with the combustible raw material gas or the mixed gas generated in the upstream mixing stage, and the premixed gas that has reached the combustible concentration range in the final mixing stage is generated. The combustible gas mixing method according to claim 1, wherein:   Combustible raw material gas prepared at each downstream mixing stage is mixed with the oxygen-containing gas or the mixed gas generated at the upstream mixing stage, and the premixed gas that has reached the combustible concentration range is generated at the final mixing stage. The combustible gas mixing method according to claim 1, wherein: A mixer that generates a premixed gas in a flammable concentration range by mixing a combustible raw material gas and an oxygen-containing gas,
A gas nozzle for forming a gas jet by supplying any one of the combustible raw material gas and the oxygen-containing gas to a mixing stage in a mixer;
A swirl flow of either the combustible raw material gas or the oxygen-containing gas is formed at the downstream position of the gas nozzle and around the gas jet stream from the upstream to form the swirl flow and the gas from the upstream A plurality of swirling and mixing means disposed at each of a plurality of mixing stage positions for mixing the jet and ejecting it downstream;
A combustible gas mixer, characterized in that a gas component concentration in a mixed gas generated at each mixing stage position is changed to generate a premixed gas that reaches the combustible concentration range at the final mixing stage position.   Each of the gas nozzle and the swirl mixing unit is attached to a partition plate that partitions the mixing stage, and the mixer unit cell unit is formed by coaxially stacking the gas nozzle and the swirl mixing unit of each partition plate. The combustible gas mixer according to claim 4.   The same number of gas nozzles and swirl mixing means of each partition plate are attached to corresponding positions, and a plurality of mixer cell units are formed by coaxially stacking the gas nozzles and swirl mixing means of each partition plate. The combustible gas mixer according to claim 5, wherein the combustible gas mixer is used.   The swirl mixing unit includes a swirler having a plurality of swirl vanes arranged in a circumferential direction, and a guide duct for guiding swirl flow flowing out of the swirl vanes to the mixing stage. The combustible gas mixer according to 5 or 6.   The combustible gas mixer according to claim 7, wherein the partition plates are stacked using the swirler as a spacer.

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