JP2008214165A - 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 the oxygen-containing gas is fed along a jet J1 of the combustible raw material gas, part of the oxygen-containing gas is taken in the jet J1 and mixed with the jet by an ejector effect caused along with the jet J1, and the fuel concentration of a mixed gas in a mixing area MX1 formed on a downstream side of the jet J1 is kept out of the combustible concentration range irrespectively of a change in momentum which the jet has. <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 (such as methane) is pressurized and heated to about 4 MPaG and about 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 steam 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 mixed gas, 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 a mixed gas 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.

Also, when changing the operating conditions of the plant, it is difficult to maintain the fuel / oxygen-containing gas ratio at a desired value by adjusting the flow rates of the raw material gas and the oxygen-containing gas at the same time as an operational problem. In some cases, there is a problem that self-ignition and flashback are likely to occur during a transition period of plant operation.
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 in particular, without causing abnormal combustion such as flashback or self-ignition as much as possible, particularly changing the fuel supply amount, It is effective for safe operation without causing abnormal combustion even during plant operation transients, and the generated high-pressure and high-temperature premixed gas is suitable for large reactors, for example, as a reformed mixed gas An object is to provide a combustible gas mixing method and a combustible gas mixer that can be used.

  According to the combustible gas mixing method for producing 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 1, the combustible raw material gas and the oxygen-containing gas An ejector that ejects one of them, supplies either the combustible raw material gas or the oxygen-containing gas along the jetted jet, and generates a part of the supplied other gas along with the jet The fuel concentration in the mixed gas in the mixed region formed downstream of the jet is mixed and mixed with the jet by the effect, and the fuel concentration in the mixed gas formed outside the combustible concentration range regardless of changes in the momentum of the jet. It is characterized by maintaining.

  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 2, the combustible raw material gas and the oxygen-containing gas A gas nozzle for ejecting one of the gases as a jet, a gas supply means for supplying the other one of the combustible raw material gas and the oxygen-containing gas along the jet of the one gas, and a downstream of the gas nozzle. And a duct means for generating an ejector effect associated with the jet flow, taking a part of the other gas into the jet flow, and forming a mixing region downstream of the jet flow, the duct means comprising: A mixing region is formed in the duct means, and the fuel concentration in the mixed gas in the mixing region is maintained outside the combustible concentration range regardless of a change in momentum of the jet. To.

According to a third aspect of the present invention, in the combustible gas mixer according to the second aspect, the duct means includes a jet of mixed gas generated in the mixing area and the other in the downstream mixing area of the duct means. And the remainder of the gas is mixed to produce the premixed gas.
According to a fourth aspect of the present invention, the combustible gas mixer according to the third aspect further comprises at least one wake duct means disposed at the wake position of the duct means, and the at least one wake The flow duct means generates an ejector effect accompanying the jet of the mixed gas generated in the mixing region, and causes the jet to take in a further part of the other gas, so that the second duct is formed in the wake duct means. A mixed region is formed, and the concentration of the raw material gas component in the mixed gas generated in each of the mixed region, at least one second mixed region, and the downstream mixing region is changed, and the combustible concentration range is determined in the downstream mixing region. A premixed gas that reaches the region is generated.

  According to the invention of claim 5, in the combustible gas mixer according to claim 2 or 3, the support means for supporting the gas nozzle and the duct means, and the outer periphery of the jet of the one gas and the other gas flow are covered. A mixing vessel cell, wherein the mixing vessel cell is accommodated in the mixing vessel cell so as to accommodate the gas nozzle and the duct means supported by the supporting means.

  According to a sixth aspect of the present invention, in the combustible gas mixer according to the fourth aspect, the gas nozzle, the duct means and the support means for supporting at least one wake duct means, the jet of the one gas and the other A mixing vessel cell that covers the outer periphery of the gas flow, and the mixing nozzle unit includes a gas nozzle supported by the support means, a duct means, and at least one wake duct means. It is formed.

  According to the invention of claim 7, a plurality of mixer units of the combustible gas mixer of claim 5 or 6 are provided.

  According to the invention of claim 1, if the combustible raw material gas used in the reforming process and the like and the oxygen-containing gas are mixed at once, there is a risk of entering the combustible concentration range locally. A part of the other gas is taken into the jet and mixed with the jet by the ejector effect generated with the jet of the one gas. The amount of part of the gas taken into the jet is preferably set to an amount that does not enter the flammable concentration range even locally. The ejector effect is obtained in proportion to the momentum (mass × velocity) of the jet. Therefore, if the amount of gas increases, the amount of the other gas taken into the jet increases accordingly. The fuel concentration in the mixed gas in the mixing region formed downstream can be maintained outside the combustible concentration range regardless of the change in the momentum of the jet. When the remainder of the other gas is added to the mixed gas thus mixed, the desired combustible concentration range can be finally reached, and the premixed gas can be generated safely.

  In many processes, such as natural gas and methane gas reforming processes, a combustible source gas is usually ejected from a gas nozzle and the combustible source gas concentration is on the fuel rich side and out of the combustible concentration range. Along with this, it is desirable to supply an oxygen-containing gas, and first take a part of it into the jet and mix it with the jet to finally reach the desired combustible concentration range, but depending on the process, the combustible raw material gas concentration It may be preferable to first mix a part of the combustible raw material gas into the jet of oxygen-containing gas that is on the fuel lean side and out of the combustible concentration range, and finally reach the desired combustible concentration range. The desired mixing method can be selected according to the process.

  According to the combustible gas mixer of the present invention according to claim 2, the mixing method according to claim 1 is realized. That is, the duct means is disposed downstream of the gas nozzle and has a function of generating an ejector effect associated with the jet, so that either the combustible raw material gas or the oxygen-containing gas is ejected as a jet by the gas nozzle. Then, a negative pressure is generated by the jet flow, and a part of the other gas can be taken into the duct means in the duct means, and a mixed region is formed there. Since this mixing region is formed by a strong shear mixing layer formed by a jet, the two gases are uniformly mixed.

As described above, since the ejector effect is obtained in proportion to the momentum (mass × velocity) of the jet flow, the amount of the other gas taken into the jet flow increases as the gas amount increases. As a result, the fuel concentration in the mixed gas in the mixing region can be maintained outside the combustible concentration range regardless of the change in the momentum of the jet.
Finally, in the wake mixing region of the duct means, the jet of the mixed gas generated in the mixing region and the remainder of the other gas are mixed to generate a premixed gas in the combustible concentration range region. (Claim 3) However, obtaining uniform mixing in the mixing region as described above eliminates the existence of a flammable concentration region locally, and unexpected combustion due to spontaneous combustion, flashback, or the like is local. Even if it occurs, the propagation of the flame can be prevented.

  According to the invention of claim 4, at least one wake duct means is further added, and a mixing region utilizing the ejector effect is formed in multiple stages in the wake duct means (second mixing region). By sequentially changing the raw material gas component concentration in the mixed gas in each of the mixed regions, it is possible to obtain a premixed gas that has reached a uniform desired combustible concentration range region in the downstream mixing region.

  According to the fifth and sixth aspects of the present invention, the gas nozzle and the duct means (and at least one wake duct means) supported by the support means are accommodated in the mixing vessel cell, and the mixer unit is accommodated. If it is possible to form as many mixer units as necessary, and a mixer is formed by combining a plurality of mixer cell units (claim 7), a process apparatus such as a synthesis gas production plant Even if the capacity of the mixer is increased in response to the increase in size, it becomes possible to supply a premixed gas having a uniform concentration, and the process apparatus can be increased in size.

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.
The mixer 10 for generating the premixed gas includes a gas nozzle 12 that ejects a combustible raw material gas (fuel) as a jet J1, gas supply means (not shown) that supplies an oxygen-containing gas, and a downstream side of the gas nozzle 12. And a baffle pipe (ducting means) 14 that causes an ejector effect associated with the jet J1 and takes a part of the oxygen-containing gas into the jet to form a mixing region MX1 downstream of the jet. Yes. In addition, the gas nozzle 12 and the baffle pipe 14 are arranged coaxially with appropriate separation in the flow direction of the jet flow J1, and in FIG. 2, the gas nozzle 12 is shown as a straight pipe for simplicity of explanation. However, the nozzle tip shape, the pipe diameter, the positional relationship with the baffle pipe 14 and the like may be appropriately formed in a suitable shape in order to obtain a more remarkable ejector effect.

  The baffle pipe 14 expands in a trumpet shape toward the upstream side and is reduced in diameter toward the downstream side. In order to obtain a more remarkable ejector effect, the tube diameter, the degree of diameter reduction, etc. of the baffle tube 14 may be appropriately formed in a suitable shape or the like. As the duct means of the present invention, an ejector effect can be obtained. If so, a baffle plate, a diffuser, or the like in which two plates are opposed to each other may be used instead of the baffle pipe, the wall shape of the mixing vessel cell 18 defining the outer peripheral flow path of the fuel and oxygen-containing gas, the shape of the catalyst layer 2, etc. It is appropriately selected depending on. In any case, the shape and the like of the baffle pipe 14 is jetted by the ejector effect of the jet J1 because the fuel concentration of the mixed gas generated in the mixing region MX1 must be maintained outside the combustible concentration range, as will be described later. It is determined by the amount of oxygen-containing gas taken in.

  A required amount of fuel gas (methane) is supplied to the gas nozzle 12, and a fuel jet J <b> 1 is ejected from the tip nozzle toward the baffle pipe 14. The mixing vessel cell 18 is supplied with an oxygen-containing gas comprising oxygen and water vapor from an oxygen water vapor supply device (not shown), and the supplied oxygen-containing gas flows downstream along the jet J1. When the flow of this oxygen-containing gas reaches the baffle pipe 14, a part f1 flows smoothly along the inner wall surface of the baffle pipe 14, but the flow f2 flowing outside the baffle pipe 14 is at the upstream edge of the baffle pipe. The vortex flow f3 is formed by peeling.

The fuel gas and the oxygen-containing gas supplied to the mixer 10 are previously pressurized and heated to the pressure and temperature as described above. When these are uniformly mixed, the premixed gas in the combustible concentration range is Generated.
When the fuel jet J1 is ejected toward the baffle pipe 14, the inside of the baffle pipe 14 becomes negative with respect to the outer flow f2 due to the ejector effect, and a part of the oxygen-containing gas flow is drawn into the baffle pipe 14. Then, it is taken in and mixed with the jet J1. A shear layer is formed between the two flows of the fuel gas and the oxygen-containing gas downstream of the jet J1 and inside the baffle pipe 14 to form a mixed region MX1. In the mixing region MX1, strong turbulence occurs, and intense mixing of the fuel gas and the oxygen-containing gas occurs, and a uniform mixed gas of these gases is generated.

As described above, the ratio of the amount of fuel gas flowing into the mixing region MX1 and the amount of oxygen-containing gas is determined by the shape of the gas nozzle 12 and the baffle pipe 16, etc., but in the mixed gas generated in this region The shape and the like of the baffle pipe 14 are determined so that the fuel concentration becomes a value sufficiently separated from the above-described combustible concentration range.
On the outside of the baffle pipe 14, there is a vortex region f3 formed by separating the flow of the oxygen-containing gas, and violent turbulent mixing is generated by this vortex region to form a wake mixing region MX. In the wake mixing region MX, the mixed gas from the mixing region MX1 and the remainder of the oxygen-containing gas are mixed to finally generate a uniform premixed gas in the combustible concentration range region.

  In the present invention, by using the gas nozzle 12 and the baffle pipe 14, even if the ejector effect occurs and the amount of fuel gas supplied to the gas nozzle 12 fluctuates, it is proportional to the flow rate of the jet J1 and the momentum of the jet J1. Since the amount of the oxygen-containing gas drawn into the baffle pipe 14 also automatically changes, the fuel concentration of the mixed gas generated in the mixed region MX1 is maintained at a substantially constant value sufficiently far from the combustible concentration range region. In the mixing regions MX1 and MX, as described above, a strong shear boundary layer is generated by vortex or the like, and a uniform mixed gas is generated in each.

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.
Moreover, in the said embodiment, although combustible raw material gas was jetted to the gas nozzle 12, and oxygen-containing gas was supplied along the gas jet, conversely, oxygen-containing gas was jetted from the gas nozzle 12, and combustible raw material gas was made into the gas You may make it supply along a jet, and what is necessary is just to select the aspect suitable for the process apparatus in which the mixer of this invention is used.

  3 and 4 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. That is, the mixer 10 is provided with a plurality of mixer cell units 10A, these mixer cell units 10A, a partition plate 10c that partitions the fuel gas chamber 10a in the reactor, and an oxygen in cooperation with the partition plate 10c. A partition plate 10d that partitions the contained gas chamber 10b is provided. The necessary number of mixer cell units 10A attached to the partition plate 10c are arranged at appropriate positions according to the inlet shape of the catalyst layer 2 and the like, for example, in a staggered pattern.

  Each partition plate 10c and partition plate 10d accommodated in the reactor 1 have a substantially disk shape that matches the internal shape of the reactor 1, and the fuel gas chamber 10a and the oxygen-containing gas chamber 10b formed therein. Are defined in an airtight manner. Fuel (methane) is supplied from the fuel supply port 1a of the reactor 1 to the fuel gas chamber 10a. The oxygen-containing gas chamber 10b is supplied with an oxygen-containing gas from an oxygen-containing gas port 1b of the reactor 1, and a fuel gas chamber 10a, a port 1a, an oxygen-containing gas chamber 10b, a port 1b, etc. And part of the gas supply means of the present invention together with the oxygen-containing gas heating device and the like.

Details of the configuration of each mixer cell unit 10A will be described with reference to FIG. In addition, in FIG. 2, although the schematic component of the mixer 10 was demonstrated in order to understand the combustible gas mixing method which concerns on this invention, it corresponds to these components and has substantially the same function, The same reference numerals are given and detailed descriptions thereof are omitted.
The mixer cell unit 10A shown in FIG. 4 includes a baffle pipe 14 as a wake duct means in addition to the baffle pipe 14 which is a component shown in FIG. The gas nozzle 12 is supported by a support means as will be described later, and is accommodated in a cylindrical mixing container cell 18.

  The upper end of the mixing vessel cell 18 is fixed to the dividing wall plate 10c so as to be suspended from the dividing wall plate 10c, and the mixing vessel cell 18 is inserted into a hole formed in the dividing wall plate 10d at a substantially middle position of the vessel wall of the vessel cell 18. It is fitted and attached. The lower end 18b of the container cell 18 opens to the catalyst layer 2 as desired, and expands in the vicinity of the lower end 18b so that the premixed gas generated inside diffuses uniformly toward the inlet end surface of the catalyst layer 2. Yes. Along the peripheral wall in the vicinity of the upper end of the container cell 18, a large number of openings 18 a are provided at equal positions in the circumferential direction, and the inside of the container cell 18 communicates with the oxygen-containing gas chamber 10 b through the openings 18 a. Then, the oxygen-containing gas is supplied from the oxygen-containing gas chamber 10b through the numerous openings 18a around the fuel jet J1 and along the jet J1.

  The gas nozzle 12 is fixed to the central axis position of the mixing vessel cell 18 through the partition plate 10c, and the partition plate 10c functions as a support means for supporting the gas nozzle 12. The upper end 12a of the gas nozzle 12 is open to the fuel gas chamber 10a. The gas nozzle 12 expands in a trumpet shape so as to suppress the pressure loss of the gas flow, and allows the fuel gas from the fuel gas chamber 10a to flow into the container cell 18. Leading to.

  At the lower end of the gas nozzle 12, 14 and the wake baffle pipe 16 are coaxially connected via struts 14 a and 16 a as support means, and these baffle pipes are suspended from the gas nozzle 12 by the support means. . The wake baffle pipe 16 functions in the same manner as the baffle pipe 14 to produce an ejector effect associated with the jet J2 of the mixed gas ejected from the upstream mixing region MX1, and takes in a further portion of the oxygen-containing gas into the jet. Thus, the second mixing region MX2 is formed in the wake baffle pipe 16. Then, similarly to the baffle pipe 14 shown in FIG. 2, the flow flowing outside the rear baffle pipe 16 is separated at the upstream edge of the baffle pipe 16 to form a vortex flow f3. That is, in the embodiment shown in FIG. 4, the vortex flow f3 is not formed outside the baffle pipe 14, but outside the wake baffle pipe 16, and the wake mixing area MX is formed.

  In the mixer 10 of the embodiment shown in FIG. 4, the mixing region MX2 is formed by the baffle tube 14 and the wake baffle tube 16 in addition to the mixing region MX1 and the wake mixing region MX. As described above, the amount of oxygen-containing gas supplied to each mixing region is determined by appropriately setting the shape of the baffle pipe 14 and the downstream baffle pipe 16, and the fuel concentration ratio in the mixed gas generated in each mixing region. Can be set to a desired value. When the shape of the baffle pipe is set, as described above, even if the amount of fuel gas supplied to the gas nozzle 12 varies due to the ejector effect, the flow rate of the jet J1 and the momentum of the jet J1 are proportional. The amount of oxygen-containing gas drawn into the baffle pipe 14 automatically changes, and similarly, the amount of oxygen-containing gas drawn into the downstream baffle pipe 16 also changes automatically, so that the mixed gas generated in the mixing regions MX1 and MX2 Is maintained at a constant value substantially as set. Although these fuel concentration ratios gradually approach values within the flammable concentration range, they can be set to substantially constant values that are sufficiently far from the flammable concentration range, effectively preventing flame propagation due to self-ignition and flashback. can do.

  In addition, even when a premixed gas that is finally in the flammable concentration range is generated in the wake mixing region MX, a strong shear boundary layer due to vortex flow or the like occurs in the upstream mixing regions MX1 and MX2, as described above, A uniform gas mixture is generated in each case. Since such a mixed gas is supplied to the final mixed region MX, compared with the case where the fuel gas and the oxygen-containing gas are mixed all at once, the generation of the fuel rich region can be suppressed locally, and the self-ignition And can suppress backfire.

In the above-described embodiment shown in FIG. 4, an example in which only one wake baffle pipe 16 is added is illustrated. However, the number of wake baffle pipes can be increased or decreased as necessary, and the wake baffle pipe can be increased or decreased. By adding the above, a more uniform premixed gas can be obtained.
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 arranging 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. Further, the mixer cell unit 10A can be easily increased or decreased according to the production scale of the synthesis gas production plant, and a uniform premixed gas can be supplied to the catalyst layer regardless of the production scale of the synthesis gas.

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. The conceptual diagram for demonstrating the method to obtain uniform premixed gas by the combustible mixing method which concerns on this invention. 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 nozzle 14 Buffer pipe (duct means)
16 Wake buffer pipe (wake duct means)
18 Mixing vessel cell J1 Jet MX Wake mixing region MX1 Mixing region MX2 Second mixing region

Claims (7)

A mixing method for generating a premixed gas in a flammable concentration range by mixing a combustible raw material gas and an oxygen-containing gas,
Either one of the combustible raw material gas or the oxygen-containing gas is ejected,
Along the jetted jet, either the combustible raw material gas or the oxygen-containing gas is supplied,
A part of the supplied other gas is taken into the jet by the ejector effect generated with the jet, and mixed with the jet,
A combustible gas mixing method characterized in that the fuel concentration in the mixed gas in the mixed region formed downstream of the jet is mixed and maintained outside the combustible concentration range regardless of the change in momentum of the jet. 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 that ejects one of the combustible raw material gas and the oxygen-containing gas as a jet; and
Gas supply means for supplying one of the combustible raw material gas and the oxygen-containing gas along the jet of the one gas;
A duct means disposed downstream of the gas nozzle to cause an ejector effect associated with the jet, and to incorporate a part of the other gas into the jet to form a mixing region downstream of the jet. ,
The duct means forms the mixing region in the duct means,
The combustible gas mixer, wherein the fuel concentration in the mixed gas in the mixed region is maintained outside the combustible concentration range regardless of a change in momentum of the jet.   The duct means generates the premixed gas by mixing the jet of the mixed gas generated in the mixing area and the remainder of the other gas in the wake mixing area of the duct means. The combustible gas mixer according to claim 2. And further comprising at least one wake duct means disposed at a wake position of the duct means,
The at least one wake duct means generates an ejector effect associated with a jet of mixed gas generated in the mixing region, and causes the jet to take in a further part of the other gas, thereby wake duct means. Forming a second mixing region therein,
The raw material gas component concentration in the mixed gas generated in each of the mixing region, at least one second mixing region and the wake mixing region is changed, and the pre-combustion concentration range region is reached in the wake mixing region. The combustible gas mixer according to claim 3, wherein a mixed gas is generated. Support means for supporting the gas nozzle and duct means;
A mixing vessel cell covering the outer periphery of the one gas jet and the other gas flow,
The combustible gas mixer according to claim 2 or 3, wherein a gas mixer and a duct means supported by the support means are accommodated inside the mixing container cell to form a mixer unit. Support means for supporting the gas nozzle, duct means and at least one wake duct means;
A mixing vessel cell covering the outer periphery of the one gas jet and the other gas flow,
The mixer unit is formed by accommodating the gas nozzle, the duct means and at least one wake duct means supported by the support means in the mixing container cell. Flammable gas mixer.   The combustible gas mixer according to claim 5 or 6, comprising a plurality of the mixer units.

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