System for injecting a reactive gas-containing component into a synthesis reactor

Abstract

System (1) for injecting a reactive gas-containing component into a synthesis reactor, comprising: - a static mixing element (10) and - a means (18) arranged within the static mixing element (10) for injecting the reactive gas-containing component into the synthesis reactor, - wherein the static mixing element (10) consists of at least three layers and the individual layers consist of folded individual elements (12) provided with numerous openings (14), - and wherein the means (18) arranged within the static mixing element (10) for injection is a perforated tube.

Description

Technical field

[0001] The present invention relates to a system for injecting a gas-containing component into a synthesis reactor, a synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas comprising the system according to the invention, and a method for dehydrogenating a partially dehydrogenated hydrocarbon-containing process gas using the system according to the invention. Furthermore, the present invention relates to the use of the system according to the invention for injecting a gas-containing component into a synthesis reactor, wherein the synthesis reactor is preferably a synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas. Technical background

[0002] In a synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas, an alkane is sequentially dehydrogenated catalytically to an alkene in an allothermal reformer and subsequently in an autothermal oxyreactor. Alkene selectivity plays a central role with regard to the economic viability of the entire process. In currently known alkane dehydrogenation plants, it has been observed that, firstly, undesirable byproducts are formed, and secondly, the desired alkene selectivity is not achieved.

[0003] Existing systems for injecting the gas-containing component into the synthesis reactor, such as the ring distributor known from DE 103 59 744 A1, allow the required average residence time to be adjusted by changing the distance between the injection system and the catalyst surface, as well as the inflow velocity of the gas-containing component. However, they do not achieve the necessary mixing, leading to increased formation of byproducts, including oxygenates. The formation of these byproducts causes significant problems in the downstream carbon dioxide absorbers due to the formation of foaming agents and solids, and also reduces the economic efficiency of the process.

[0004] The ring distributor known from DE 103 59 744 A1 consists of concentrically arranged pipes, each containing many individual nozzles. Since the nozzles must be individually attached to the pipes, manufacturing such a ring distributor is very expensive. Furthermore, due to its rigid arrangement in the oxyreactor, it requires complex adjustment to set the mean residence time both at the beginning of a process and during the process, for example, by adjusting for catalyst bed shrinkage. Summary of the invention

[0005] The invention is therefore based on the objective of providing a system for injecting a reactive gas-containing component, with which the disadvantages of the prior art can be overcome.

[0006] This problem is solved by a system for injecting a reactive gas-containing component into a synthesis reactor with the features of claim 1.

[0007] According to the invention, the system comprises a static mixing element and a means for injecting a reactive gas-containing component into a synthesis reactor, arranged within the mixing element. As the reactive gas-containing component exits within the mixing element, it is deflected multiple times by the mixing element on its way to the catalyst bed, so that it mixes uniformly with a process gas present in the synthesis reactor, which flows through the static mixing element on its way to the catalyst bed. The desired residence time for the reactive gas-containing component can be adjusted by the gas velocity of the reactive gas-containing component and the size of the static mixing element, in particular by the distance of the injection means from the catalyst bed.

[0008] According to a further aspect of the present invention, the static mixing element consists of at least three layers, the individual layers comprising folded elements with numerous openings. This gives the mixing element a modular structure. The openings in the individual elements serve two purposes: firstly, they accelerate and redirect the process gas flow entering the reactor, into which the reactive gas-containing component is injected, in order to intensify mixing; and secondly, they ensure a uniform residence time in the mixing element by preventing backflow. The openings can be circular. Other geometric shapes are also conceivable, such as easily punched square, rectangular, or polygonal openings, or even simple slots. The folds provide cavities into which the means for injecting the reactive gas-containing component is arranged.The height of the folds can vary. Preferably, the folds have a height in the range of 10 to 100 mm. Particularly preferably, the folds have a height in the range of 15 to 50 mm, and most preferably, a height in the range of 15 to 30 mm. In a further preferred embodiment, the folds are formed at right angles. Alternatively, the folds can also be round or polygonal.

[0009] The folding height of the layer of the individual element in which the injection agent is placed above or below is determined by the amount of reactive gaseous component to be dosed. The folding heights for the other layers may vary.

[0010] In a preferred embodiment, the static mixing element consists of three to nine layers, in a more preferred embodiment of three to seven layers, and in a most preferred embodiment of four to five layers of a single element. Other compositions or combinations of layers of single elements for the static mixing element are also conceivable. These depend primarily on the backflow and the residence time.

[0011] The individual elements can be stacked in different ways to form the mixing element. According to a preferred embodiment, the individual elements can be stacked interlocked, such that the cavities formed by the folds of the individual elements run parallel to each other within a layer and interlock with each other in a layer arranged below or above, so that the cavities of one layer form an angle of 0–90°, preferably 60–90°, with a layer arranged above or below.

[0012] In a further preferred embodiment, the injection means is arranged above the first layer of the mixing element. In a three-layer structure of the mixing element, the first layer forms the single element facing the catalyst bed. Alternatively, the injection means can be arranged below or above the second layer of the static mixing element. Preferably, the means can be arranged below or above the second to penultimate layer of the static mixing element.

[0013] In general, the individual elements arranged above the injection unit prevent backflow of the reactive, gas-containing component being injected into the gas space above the mixing element, thus preventing undesirable side reactions caused by long residence times. The layers below the injection unit ensure rapid and intensive mixing. The maximum desired or permissible residence time in the catalyst-free mixing zone limits the number of layers below the injection unit.

[0014] Preferably, the individual elements consist of a material selected from the group consisting of stainless steels, carbon steel, Hastelloy, Monel, aluminum, copper bronze, brass, titanium, nickel, niobium, copper, PP, PVC-C, PVDF, PTFE, PEEK, or carbon (CFC). Particularly preferably, the individual elements consist of the same material as the reactor.

[0015] In a further embodiment, the system according to the invention also includes a fixing element. The fixing element serves to fix the uppermost layer of the catalyst bed. In its simplest embodiment, the fixing element can be a perforated sheet or metal mesh.

[0016] It is also conceivable that the mixing element itself exerts a fixing effect on the catalyst bed. In a preferred embodiment, the mixing element rests on the catalyst bed. The weight of the mixing element holds the catalyst particles down and also prevents their lateral movement. Due to the modular design, complex adjustments are unnecessary, as the residence time can be set as required.

[0017] According to a preferred embodiment, the injection means is a perforated tube. The perforation can be in a uniform or random pattern. The perforation can be circular or in the form of slots. A perforated tube is the simplest possible embodiment and therefore very cost-effective.

[0018] The invention further relates to a synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas comprising a reformer and an oxyreactor containing the system according to the invention for injecting a reactive gas-containing component.

[0019] Preferably, the reformer is an allothermally operated reformer and the oxyreactor is an autothermally operated reactor.

[0020] Preferably, the system according to the invention is arranged in the flow direction of the process gas upstream of a first catalyst bed of an oxyreactor, so that the process gas, which is partially dehydrated in the reformer, first flows through the static mixing element on its way to the catalyst bed.

[0021] In a further preferred embodiment, the oxyreactor comprises a second system arranged between the first catalyst bed and a second catalyst bed.

[0022] Furthermore, the invention relates to a process for the dehydrogenation of a partially dehydrogenated hydrocarbon-containing process gas, comprising the process steps: – providing an oxyreactor with a system for injecting a reactive gas-containing component, – injection of the reactive gas-containing component, – introducing a partially dehydrated hydrocarbon-containing process gas into the oxyreactor, wherein the partially dehydrated hydrocarbon-containing process gas flows through the mixing element arranged in the oxyreactor, and – Dehydration of the partially dehydrated hydrocarbon-containing process gas into a dehydrated process gas.

[0023] A dehydrated process gas within the meaning of the invention is a process gas that contains a higher proportion of unsaturated hydrocarbons compared to a partially dehydrated hydrocarbon-containing process gas.

[0024] Preferably, the reactive gas-containing component is an oxygen-containing vapor stream, and the partially dehydrated hydrocarbon-containing process gas is a gas mixture comprising molecules with 2 to 6 carbon atoms, preferably 3 or 4 carbon atoms. Most preferably, the partially dehydrated hydrocarbon-containing process gas is a gas mixture comprising propane / propene or butane / butene.

[0025] The oxygen-containing vapor stream more preferably has an oxygen content of at least 1 vol.%, more preferably 10–30 vol.% and most preferably 15–25 vol.%.

[0026] The present invention also relates to the use of the system according to the invention for injecting a reactive gas-containing component into a synthesis reactor, preferably a synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas. Brief description of the drawings

[0027] The invention will be explained in more detail below with reference to the drawings. Specifically, the drawings show:

[0028] Fig. 1 the system according to the invention for injecting a gas-containing component,

[0029] Fig. 2 comprising an oxyreactor, the system according to the invention. Description of preferred embodiments

[0030] Fig. Figure 1 shows the system according to the invention. 1 for injecting a gas-containing component. In the Fig. In the embodiment shown in 1, the system comprises 1 a static mixing element 10 , which consists of three layers. The individual layers are connected by folded sections with openings. 14 individual elements provided 12 formed. The openings 14 In the present embodiment, they are circular. This is due to the folding of the individual elements. 12 cavities will be 16 formed, which extend like a channel through the mixing element10 extend. The means for injecting the reactive gas-containing component is placed into this. 18 The introduced element, which in the present embodiment is a perforated tube from which the oxygen-water vapor mixture can flow out, has its layers arranged at an angle to each other, so that the cavities 16 of a single element 12 to a single element arranged above or below 12 form an angle of 90°.

[0031] Fig. Figure 2 shows an oxyreactor 20 containing the system according to the invention 1 The oxyreactor 20 shows an entrance 22 on, through which the partially dehydrogenated hydrocarbon-containing process gas from a reformer flows in. Inside the oxyreactor 20 is a catalyst bed 28 as well as above the catalyst bed 28 the system according to the invention 1 arranged. The area within the mixing element10 arranged means for injecting the reactive gas-containing component 18 is connected to a supply line 26 connected, via which the reactive gas-containing component enters the oxyreactor 20 is introduced. The partially dehydrated, hydrocarbon-containing process gas flows through the system. 1 and the catalyst bed 28 . Via an outlet 24 A dehydrated process gas then leaves the oxyreactor. 20 . Commercial applicability

[0032] Systems of the type described above are used to inject a reactive gas-containing component into a synthesis reactor, wherein the synthesis reactor is preferably a synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas. Reference symbol list 1 system 10 Static mixing element 12 individual elements 14 openings 16 Cavity 18 Means for injecting the reactive gas-containing component 20 Oxyreactor 22 Admission 24 outlet 26 Supply line 28 catalyst bed QUOTES INCLUDED IN THE DESCRIPTION

[0033] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0034] DE 10359744 A1 [0003, 0004]

Claims

[1] System for injecting a reactive gas-containing component into a synthesis reactor, comprising: – a static mixing element and – a means arranged within the mixing element for injecting the reactive gas-containing component into the synthesis reactor. [2] System according to claim 1, wherein the static mixing element consists of at least three layers and the individual layers consist of folded individual elements provided with numerous openings. [3] System according to claim 2, wherein the static mixing element consists of three to nine, preferably three to seven and more, preferably four to five layers of a single element. [4] System according to any one of the preceding claims 1 to 3, wherein the injection means is arranged above a first layer. [5] System according to any one of the preceding claims 1 to 4, wherein the individual elements consist of a material selected from the group consisting of stainless steels, carbon steel, Hastelloy, Monel, aluminum, copper bronze, brass, titanium, nickel, niobium, copper, PP, PVC-C, PVDF, PTFE, PEEK or carbon (CFC) or mixtures thereof. [6] System according to any one of the preceding claims 1 to 5, further comprising a fixing element. [7] System according to any one of the preceding claims 1 to 6, wherein the injection means is a perforated tube. [8] Synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas, comprising: – a reformer and – containing an oxyreactor and a system for injecting a reactive gas-containing component. [9] Synthesis reactor according to claim 8, wherein the system is arranged in the flow direction of the process gas upstream of a first catalyst bed, so that the process gas first flows through the static mixing element on its way to the catalyst bed. [10] Synthesis reactor according to claim 8 or 9, wherein the oxyreactor comprises a second static system arranged between the first catalyst bed and a second catalyst bed. [11] Synthesis reactor according to any one of the preceding claims 8 to 10, wherein the static mixing element rests on the catalyst bed. [12] Process for the dehydrogenation of a partially dehydrogenated hydrocarbon-containing process gas, comprising the process steps: – providing an oxyreactor with a system for injecting a reactive gas-containing component, – injecting the reactive gas-containing component, – introducing a partially dehydrated hydrocarbon-containing process gas into the oxyreactor, wherein the partially dehydrated hydrocarbon-containing process gas flows through the static mixing element arranged in the oxyreactor, and – Dehydration of the partially dehydrated hydrocarbon-containing process gas into a dehydrated process gas. [13] Method according to claim 12, wherein the reactive gas-containing component is an oxygen-containing vapor stream and the partially dehydrated hydrocarbon-containing process gas comprises 2 to 6 carbon atoms, preferably 3 or 4 carbon atoms. [14] Use of a system for injecting a reactive gas-containing component into a synthesis reactor, preferably a synthesis reactor for the catalytic dehydrogenation of a hydrocarbon-containing process gas.

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