Apparatus for manufacturing nitrile and its use

Abstract

The present invention relates to the problem of describing an electrically heated reactor for the production of hydrogen cyanide and other nitriles that allows for distinct temperature profiles and is sufficient with inexpensive standard components. The essential part of the apparatus (0) according to the present invention is a chamber (1) made of gas-permeable insulating material that represents the actual reaction space. An electrical heating element (5) protrudes into the chamber (1), thereby allowing the chamber (1) to be heated from the inside by the heating element (5). The electrical connections of the heating element are located outside the reaction space, but inside the surrounding shell. That is, unlike the BMA method practiced industrially, heat is generated within the reaction space rather than being transported from the outside into the reaction space. Heat generation is carried out by the conversion of electrical energy by the heating element (5) according to the principle of resistance heating. To ensure the gastightness of the apparatus (0), a shell (9) is provided that gastightly surrounds the chamber (1).

Description

[Technical Field]

[0001] The present invention relates to an apparatus for producing at least one product gas from at least one starting gas. In particular, the apparatus is intended for the production of nitriles. Furthermore, the present invention relates to the production of nitriles, in particular hydrogen cyanide, and the use of the apparatus in providing a negative control output.

[0002] Hydrogen cyanide (HCN), the simplest nitrile, is an important synthetic unit in organic chemistry. On an industrial scale, the production of hydrogen cyanide is often carried out according to the Andrussau process or the BMA process.

[0003] The introduction of cyanide production technology was as follows: Gail, E., Gos, S., Kulzer, R., Loroesch, J., Rubo, A., Sauer, M., Kellens, R., Reddy, J., Steier, N. and Hasenpusch, W. (2011). Cyano Compounds, Inorganic. In Ullmann's Encyclopedia of Industrial Chemistry, (Ed.). DOI 10.1002 / 14356007.a08_159.pub3

[0004] In the BMA process (BMA = hydrogen cyanide composed of methane and ammonia), hydrogen cyanide is produced from methane (CH4) and ammonia (NH3) in a strongly endothermic reaction requiring relatively high reaction temperatures of 1000°C to 1300°C. In contrast to the Andrusseau process, the BMA process is carried out in the absence of oxygen. The need to use fossil energy carriers to supply reaction enthalpy, coupled with the low energy yield of hydrogen cyanide, results in the generation of a considerable amount of CO2.

[0005] The energy required in the BMA process is supplied within a separate combustion chamber by burning natural gas or refluxed hydrogen (H2) produced as a byproduct of the BMA process. In this case, based on the minimum temperature required for the hydrogen cyanide reaction, only a portion of the thermal energy used is utilized for the reaction itself, while the rest is used to heat the combustion air and fuel.

[0006] As an alternative energy source, HCN can be produced using electrical energy instead of fossil fuels. When using electricity from renewable sources, this method is nearly energy-neutral in terms of CO2 emissions. Furthermore, electrically heated BMA methods offer additional advantages over fossil fuel-heated BMA methods, particularly in terms of operating costs. By heating the combustion air to a high minimum reaction temperature, unavoidable energy losses on the fuel gas side can be avoided, leading to improved energy efficiency. • Because refractory materials are not required for the reactor lining, faster start-up and shutdown cycles are achieved. • More homogeneous temperature control enables higher yields, thereby reducing the specific amounts of methane and ammonia used for hydrogen cyanide production. In other words, it is known that significantly higher yields can be achieved under a homogeneous temperature distribution while simultaneously reducing by-product formation.

[0007] In terms of investment costs, electrically heated BMA equipment offers advantages over thermally heated equipment. The absence of fuel gas and exhaust gas spaces allows for more compact construction methods and higher space-time yields. Similarly, inexpensive module connectors are also possible.

[0008] Finally, the electrically operated BMA method is more sustainable: The hydrogen-containing residual gas produced can, in some cases, be used as a heating gas in downstream processes, replacing natural gas and achieving further CO2 reduction. • By eliminating the use of fire-resistant materials and implementing a process design that allows for a higher degree of automation, the ignition time (Fackelzeiten) in the event of an operational interruption can be significantly minimized. The hydrogen in the residual gas produced has a significantly lower CO2 footprint than the hydrogen produced from fossil hydrocarbons in a steam reformer, and can, in some cases, be used as a raw material for further chemical reactions after necessary purification.

[0009] For all these reasons, there is interest in developing an electrically powered BMA method that can produce hydrogen cyanide on an industrial scale.

[0010] Various concepts are known for producing HCN in electrically heated reactors.

[0011] One example describes the application of an electrically heated fixed-bed reactor for the production of hydrogen cyanide, where heating of the catalyst bed can be performed by induction; see International Publication No. 2017186437.

[0012] Another approach involves the use of a structured catalyst, a so-called monolith, made of a conductive material, as described in International Publication No. 2019228798 or International Publication No. 2021 / 063799. In the cited publications, the starting material is delivered through a catalyst-coated channel of an electrically heated structure (resistive heating).

[0013] From German Patent Application Publication No. 10317197, a reactor for the production of hydrogen cyanide by the BMA method is known, which may selectively include an induction heater or a resistance heater. Heating is carried out by a module located in a reaction space through which the reaction mixture is passed longitudinally. The reactor is surrounded by an insulating material and has a gas-tightly closed double cover. The double cover is filled with an inert gas. The drawback of this reactor is its monolithic structure, which makes the production of a defect-free homogeneous material from the green body very difficult, and it is susceptible to influences ranging from material loading to cracks due to thermal stress, and is considered complex for industrial-scale construction.

[0014] In view of this prior art, the fundamental problem of the present invention is to provide an electrically heated reactor for producing gaseous products, such as hydrogen cyanide and other nitriles, which is durable against thermal (alternating) loads, has high availability of heating elements, allows for distinct temperature profiles, and can be made with inexpensive standard components.

[0015] This problem is solved by the apparatus described in claim 1. Therefore, the first object of the present invention is an apparatus for producing at least one product gas from at least one starting gas, in particular an apparatus for producing nitrile as a product, characterized by the following: a) The apparatus comprises a chamber having a gas-permeable and insulating wall, an inlet for the starting material gas, an outlet for the product gas, and a main flow direction extending from the inlet to the outlet; b) The apparatus comprises a gas-tight shell surrounding the chamber, with inlet and outlet passages connected to the shell; c) An intermediate chamber is provided between the chamber and the shell, and this intermediate chamber surrounds the chamber, which is itself surrounded by the shell; d) The apparatus comprises at least one electrical heating element, the at least one electrical heating element extending through the chamber and having a wall that is penetrated at least once, and having at least two electrical connections located inside the intermediate chamber and outside the chamber; e) The device comprises a voltage source arranged outside the shell, the voltage source being connected to a first electrical connection of the heating element via at least a first electrical line and to a second electrical connection of the heating element via a second electrical line, the first and second electrical lines being electrically conductive through the shell; f) The device comprises at least one connection element for a filling gas source arranged outside the shell, the filling gas source being fluidically connectable to the intermediate chamber via a filling gas line, whereby the intermediate chamber can be supplied with filling gas obtained from the filling gas source; g) A catalyst is arranged in the chamber; A device comprising the above.

[0016] The main part of the device according to the invention is a chamber representing the actual reaction space. Inside the chamber there is an electrical heating element, whereby the chamber can be electrically heated from the inside by the heating element. That is, unlike the BMA method practiced industrially, heat is not transported from the outside to the reaction space but is generated for the first time within the reaction space. The generation of heat takes place in the heating element by conversion of electrical energy according to the principle of resistive heating. Unlike the BMA method practiced industrially, in the device according to the invention there is no energy loss due to exhaust gas occurring at the reaction temperature. Thereby, the energy efficiency is significantly increased.

[0017] An important aspect of the device according to the invention is that the heating element penetrates the wall of the chamber. This means that the heating element is present not only inside the chamber but also partly outside the chamber. The part of the heating element present inside the chamber serves to heat the chamber. The part of the heating element present outside the chamber serves as an electrical connection. Since each heating element requires at least two electrical connections, each heating element has at least two parts outside the chamber. Each electrical connection is present in the part of the heating element outside the chamber.

[0018] The chamber walls are lined with and / or made of insulating material, so the temperature outside the chamber is lower than the temperature inside the chamber, which makes it easier to achieve electrical contact there.

[0019] Furthermore, the feedthrough of the heating element through the wall according to the present invention is based on the finding that sealing the chamber within the region of the heating element is not possible in any case. Due to thermal expansion, sufficient play must be ensured in the feedthrough of the heating element to allow relative movement between the wall and the heating element. According to the present invention, it is desirable that the feedthrough of the heating element through the wall be gas permeable. A delivered packing gas is used to prevent the starting material gas or product gas from migrating into the intermediate chamber. This also prevents the discharge of the starting material gas or product gas from the chamber within the intermediate chamber. The pressure generated must always be at least the same as or greater than the pressure inside the chamber. It also means that.

[0020] According to the present invention, a shell is provided that gastightly surrounds the chamber to ensure the gastightness of the apparatus. Thus, an intermediate chamber is created between the shell and the wall of the chamber. According to the present invention, a filling gas is supplied to the intermediate chamber, and this filling gas cannot flow out of the intermediate chamber to the outside due to the gastightness of the shell. The filling gas is mainly nitrogen, or hydrogen, or hydrocarbons, or a mixture mainly of nitrogen, hydrogen, and hydrocarbons. The filling gas may optionally contain trace amounts of other gases. Since the residual gas generated in the BMA process may contain the filling gas mentioned above, the filling gas can be recycled from a downstream process of the method.

[0021] During operation, the gas pressure in the intermediate chamber is always adjusted to be slightly higher than the reaction pressure in the main chamber. This virtually prevents gas from entering the intermediate chamber from the main chamber. Since the shell is gas-tight, even if this does occur, it is not a significant problem. Conversely, if some of the packing gas enters the main chamber through the gas-tight wall, this is also not a serious issue.

[0022] The shell is made of a thermally conductive metal and also serves as a heat dissipation mechanism. To this end, the shell absorbs thermal radiation emitted from the walls and dissipates it into the surroundings. Since the intermediate chamber between the walls and the shell is filled only with a packing gas, thermal radiation from the walls to the shell is not obstructed.

[0023] To further improve heat dissipation, the gas-tight shell may be equipped with an additional heat exchanger. The heat exchanger is located outside the shell and is heat-conductively connected to the shell. Thus, the radiant heat absorbed by the shell is dissipated through the heat exchanger. Preferably, a cooling fluid is supplied to the heat exchanger. For this purpose, the heat exchanger is fluid-guided to a cooling fluid source via a feed path and to a cooling fluid sink via a return path. In this way, the cooling fluid flows from its source through the feed path to the heat exchanger, where it absorbs heat from the shell, and then flows to the sink via the return path. In this case, the temperature of the cooling fluid usually rises, so the temperature of the cooling fluid in the return path is higher than that in the inflow path. It is also conceivable to combine the cooling fluid source and sink in a second heat exchanger to form a cooling fluid circuit.

[0024] Suitable cooling fluids include air, gaseous or liquid nitrogen, gaseous argon, gaseous or liquid water, liquid oil, gaseous ammonia, gaseous hydrocarbons, or mixtures thereof. The cooling fluid may undergo changes in its thermodynamic state within the heat exchanger, for example, it may evaporate. It is also possible to use a mixture of starting material gases as the cooling fluid and preheat it within the heat exchanger. The return path is connected to the chamber directly or via an inlet path. In this respect, the chamber acts as a coolant sink.

[0025] Various embodiments of the heat exchanger are considered. In the first embodiment, the gas-tight shell has a cover structure (double cover). A cavity is created between the two walls of the shell, and a cooling fluid is filled into it. Heat transfer occurs directly from the inner wall of the double cover to the cooling fluid. The double cover filled with cooling fluid has the advantage that the cooling fluid is further protected against gas leakage in the event of damage to the inner shell.

[0026] Alternatively, a heat exchanger could be formed as a cooling coil wrapped around the shell. The cooling coil serves as the connection between the supply and return paths for the cooling fluid.

[0027] In its simplest form, the cooling coil is a tube filled with a cooling fluid, connected to the outer surface of a gas-tight shell via a thermal bridge. The tube, like the shell, is made of steel. The thermal bridge is a steel web welded to the tube and the shell. Thus, the steel web serves to anchor the cooling coil to the shell and also acts as a thermal bridge between the shell and the cooling coil.

[0028] Alternatively, the cooling coil can be obtained by welding an open profile to the outer surface of a gas-tight shell. In this case, the cooling fluid is present at least partially between the profile and the outer surface of the gas-tight shell. This embodiment has the advantage that heat transfer occurs directly from the shell to the cooling fluid without bypassing thermal bridges.

[0029] The chamber walls are preferably formed of multiple layers. These walls preferably comprise an outer shell made of metal and an insulator made of thermal insulation material, positioned inside the formwork. The metal shell stabilizes the chamber and releases thermal radiation into the intermediate chamber. To keep heat loss low, an insulator made of thermal insulation material with a thermal conductivity much lower than that of the metal shell is used.

[0030] The insulator is preferably made from a mineral or ceramic material having high temperature resistance and low specific thermal conductivity. Preferably, a mineral microfiber plate is used as the insulator.

[0031] It is also possible to use multi-layer insulation, in which case each insulation layer will have a different specific thermal conductivity.

[0032] Particularly preferably, the insulating wall on the chamber side has an inner layer having a closed surface. A closed surface is understood to mean a surface that is substantially porosity-free. This can be achieved, for example, by staggering individual structural elements having suitable surfaces and arranging them vertically relative to each other. In particular, the wall may comprise, on its interior, metal or ceramic elements that are not made of fibrous material. Metal and ceramic elements can be manufactured substantially porosity-free by techniques common to these materials.

[0033] In a particularly preferred embodiment, the internal walls of the chamber are envisioned to have a catalytically active coating or a catalytically activatable coating containing a catalyst on their surface. This catalytically activates the chamber walls themselves, thereby preventing deposition on the insulating material.

[0034] It may be advantageous for the chamber to have a cross-section that is not circular when viewed in the direction of the main flow. In particular, it is reasonable for the chamber to have a rectangular cross-section when viewed in the direction of the main flow. On a rectangular cross-section, the heating elements can be distributed more evenly.

[0035] Regarding the arrangement of heating elements, it should be noted that, preferably, the heating elements are arranged either in front of or behind each other when viewed in the direction of the main flow, or offset from each other. When the heating elements are arranged in front of or behind each other when viewed in the direction of the main flow, a small passage is created between the heating elements, thereby reducing the flow resistance. When the heating elements are offset from each other and arranged in front of or behind each other, there is no free passage, so the flow resistance is higher, but all flow paths are in contact with the heating elements, resulting in stronger heat transfer.

[0036] It is particularly preferable when the innermost layer of an insulated wall with a closed surface has high temperature resistance. This is achieved through material selection and processing. High temperature resistance has the advantage that the device can be quickly heated and cooled again without damaging the wall's insulation.

[0037] This is particularly advantageous when the reactor can be used to supply negative control output as part of electrical system stabilization. Conventional BMA reactors have a refractory lining, which requires heating or cooling for several hours to prevent cracking. This is too slow to supply control output, where every second counts.

[0038] A further application of the present invention is the use of a device according to the present invention that supplies a negative control output for the purpose of stabilizing an electrical system. Preferably, this device can be used to supply a negative tertiary reserve. A negative control output means that the voltage obtained from the voltage source is supplied to the device only when there is an excess of electrical output in the system to which the voltage source is connected. Conversely, if there is insufficient available electrical output, the device can be isolated from the voltage source. In either method, the system to which the voltage source is integrated is stabilized. This is particularly interesting when the system utilizes many natural energy sources whose output levels fluctuate greatly, such as wind or solar power.

[0039] The advantage of the assembly of the device according to this invention is that conventional commercially available heating elements can be used as resistance heaters, just as they are used in conventional electrically heated industrial furnaces. No special assembly of electric resistance heaters or expensive 3D printing is required.

[0040] Electrical heating elements are commercially available from silicon carbide, molybdenum silicide, or other materials and are resistant to reaction conditions.

[0041] It is advantageous when the heating element is oriented perpendicular to the flow. This ensures that the heating element is subjected to only a small temperature difference. Since the apparatus according to the present invention is set to operate in a continuous manner, during operation a region of approximately the same temperature is created through the chamber, i.e., extending through the chamber substantially perpendicular to the main flow direction of the reactants. When the heating element is positioned along this direction, the load on the heating element due to the temperature difference is very low.

[0042] Furthermore, the heating elements can be easily controlled individually. The use of individually controllable heating elements allows for precise control of the reaction's temperature progression by adjusting the temperature profile, if necessary. This enables optimization of the reaction's conversion rate and yield, and suppression of undesirable by-product formation. The temperature profile is adjusted by controlling the electrical output: the temperature profile is obtained by adjusting the output profile over the length of the reactor.

[0043] A preferred embodiment of this device is based on the design of a commercially available heating element, which is either I-shaped, U-shaped, W-shaped, or M-shaped. All of these heating elements have a virtual principal resistance axis positioned transversely to the flow direction.

[0044] The heating elements are substantially cylindrical in shape, but may have other cross-sections, such as an elliptical cross-section. An I-shaped heating element has exactly two electrical connections, i.e., one electrical connection at each end. In its installed state, the I-shaped heating elements extend linearly through the chamber, with their end-side electrical connections protruding from the wall. Their main resistance axes correspond to their longitudinal axes.

[0045] The U-shaped heating element also has two electrical connections, namely at the open ends of its legs. Therefore, the connections are on the same side. In its installed state, both legs extend parallel to each other through the chamber. The legs penetrate the wall, causing the ends with the electrical connections to protrude. The main resistance axis corresponds to the axis of symmetry.

[0046] The W-shaped heating element corresponds to a double U and has three electrical connections. These are intended for use in a three-phase system. The main resistance axis corresponds to the axis of symmetry.

[0047] The heating element is preferably positioned such that its main resistance axis forms an angle φ of at least 0° and a maximum of 90° with respect to the main flow direction. Particularly preferably, the angle φ is 90°. The main resistance axis of the heating element is perpendicular to the main flow direction. This is most advantageous from a hydrodynamic and thermodynamic standpoint.

[0048] Preferably, the device is installed so that the main flow direction extends vertically, i.e., parallel to the acceleration due to gravity. In this way, the main flow direction is not deflected by gravity, thereby maintaining the orientation of the heating element relative to the flow. Preferably, the main flow direction extends opposite to the acceleration due to gravity, i.e., upward. This prevents thermal buoyancy lateral to the flow direction.

[0049] Preferably, a number of heating elements are installed in the apparatus. These may be connected to the first and second electrical lines, and optionally to the third electrical line, in a series, parallel, or star configuration, or a combination of these connections, so as to be conductive.

[0050] Preferably, a heating element made of silicon carbide or molybdenum silicide coated with a catalyst is used. It may be reasonable to provide a protective coating on the surface of the heating element to which the catalyst is applied. This prevents chemical or physical reactions between the catalyst and the core.

[0051] Alternatively, the catalyst may be attached to a conventional non-heated catalyst support and packed into the chamber.

[0052] In the wall region, short-circuit flow may form, which can lead to an unoptimal reaction course. To avoid the formation of undesirable flow regions, additional non-heating elements may be introduced.

[0053] Therefore, the apparatus structure according to the present invention offers numerous advantages, which are particularly enhanced in the production of product gases such as hydrogen cyanide or other nitriles, for example, acetonitrile or acrylonitrile.

[0054] Therefore, a second object of the present invention is a method for producing nitrile using the apparatus according to the present invention. Such a method is as follows: a) Steps to prepare the apparatus according to the present invention, b) A step of supplying a starting material gas mixture containing at least ammonia and gaseous hydrocarbons to an inlet, c) A step of supplying a current obtained from a voltage source to a heating element, d) Step of removing the product gas mixture containing at least one formed nitrile from the outlet: It holds.

[0055] Preferably, hydrogen cyanide is produced in this manner. Hydrogen cyanide is a nitrile produced in the product gas mixture. For this reason, the starting material gas mixture must contain methane, which is a hydrocarbon. When it is desired to produce hydrogen cyanide, a platinum-containing material is used as a catalyst.

[0056] When a starting gas mixture contains additional oxygen, a potentially flammable mixture is produced. A mixture is flammable if the oxygen concentration (KO2) in the starting gas mixture exceeds the oxygen limit concentration (SGK). The oxygen limit concentration (SGK) depends on the composition of the starting gas mixture and can be found in the corresponding table. Preferably, the starting gas mixture has low oxygen content such that the oxygen concentration (KO2) is below the oxygen limit concentration (SGK). This means the starting gas mixture is not flammable, thereby ensuring operational safety with less effort.

[0057] The method for producing hydrogen cyanide operated below its ignition limit is interpreted as the BMA method. Since the thermal energy required for the reaction is supplied by electricity, this will be referred to below as the "E-BMA method".

[0058] Unlike conventional thermal BMA and Andrusso processes, the E-BMA process enables nearly complete transformation of starting materials using electrical energy, and potentially even CO2 neutrality when using green electricity (the methane used in the Andrusso process is always partially converted to CO2 based on the process characteristics).

[0059] By specially assembling the apparatus according to the present invention, the E-BMA process operated using it can be optimized in terms of yield and conversion rate, thereby making the process competitive with conventional BMA and Andrusseau processes.

[0060] In addition to the E-BMA method, the apparatus according to the present invention can also be used for similar reactions, such as the production of acetonitrile and acrylonitrile.

[0061] The apparatus according to the present invention includes at least 1 * 10 5 Pa absolute pressure and maximum 5 * 10 5 Pa absolute pressure, reaction pressure p generated inside the chamber RIt is set to be operated by a gas pressure p. Preferably, in order to reduce the pressure difference to the reaction space, the intermediate chamber has a slightly larger gas pressure p. C This occurs. Thus, almost no pressure is applied to the walls of the reaction space. On the other hand, any excess pressure relative to the ambient pressure is supported by the shell walls. The shell walls should be constructed to be appropriately pressure-resistant.

[0062] gas pressure p in the intermediate chamber C This is added by a filling gas. The filling gas is mainly nitrogen, or hydrogen, or methane, or a mixture mainly of nitrogen, hydrogen, and methane. The filling gas may optionally contain trace amounts of other gases.

[0063] Preferably, this process is operated so that the flow is evenly distributed to the heating elements within the reaction space, thereby creating a nearly constant temperature profile across each heating element with consistent surface performance. In this way, the heat load becomes more tolerable for the heating elements, and the lifespan of the heating elements is extended.

[0064] The reaction temperature range is 800°C to less than 1500°C. The reaction temperature is not necessarily the same at all locations within the chamber and may take different values ​​within the given temperature range. In the intermediate chamber, the intermediate temperature T is less than 400°C, preferably less than 150°C. c This is happening.

[0065] To maintain the temperature in the intermediate chamber below 400°C, heat is preferably dissipated from the shell via a heat exchanger by a cooling fluid. For this purpose, the cooling fluid is continuously obtained from a cooling fluid source, continuously supplied to the heat exchanger, and continuously withdrawn from the heat exchanger, so that the temperature of the cooling fluid in the supply path is lower than that in the return path.

[0066] In a special embodiment, the starting material gas mixture is used as a cooling fluid. The chamber of the apparatus acts as a cooling fluid sink. In this way, the starting material gas mixture is preheated and heat is recovered.

[0067] Examples The present invention will be described below based on examples. [Brief explanation of the drawing]

[0068] [Figure 1] This is a schematic diagram of the first embodiment of the device (linear heating element). [Figure 2] This is a schematic diagram of the second embodiment of the device (U-shaped heating element). [Figure 3] This figure shows the temperature along the central heating element in the reactor when the heating elements are oriented horizontally and vertically. [Figure 4] This diagram shows the temperature progression across the reactor. [Figure 5] This is a diagram showing the progress of the yield. [Figure 6] This figure shows the progression of the output profile in Experiment 3.

[0069] Figure 1 schematically shows the apparatus 0 according to the present invention. Apparatus 0 comprises a chamber 1 having non-gastight walls 2. The walls 2 consist of an insulating material and a shell made of a metallic material placed around them. A chemical reaction is carried out within the chamber 1. Therefore, the chamber 1 is a reaction space.

[0070] A chemical reaction is, for example, the conversion of methane (CH4) with ammonia (NH3) in the absence of oxygen (O2), which produces hydrogen cyanide (HCN) and hydrogen (H2) (E-BMA method).

[0071] The starting material stream, mainly containing methane (CH4) and ammonia (NH3), is sent as a gaseous mixture to chamber 1 through an inlet 3 via a distribution device (e.g., a perforated plate). The products, hydrogen cyanide (HCN) and hydrogen (H2), as well as any unused starting materials and by-products, are similarly withdrawn from chamber 1 in gaseous form, i.e., through an outlet 4 provided for this purpose.

[0072] Chemical conversion requires thermal energy. According to the present invention, this is generated by converting electrical energy within chamber 1. Heat is required at a temperature level in the range of 800°C to 1500°C (reaction temperature T R ).

[0073] For this purpose, a number of heating elements 5 extending through chamber 1 are provided within chamber 1. In the simplest case, the heating element 5 is a cylindrical element made of silicon carbide. Silicon carbide is highly temperature stable and is often used in practice for converting electrical energy into heat based on its physical properties. Each heating element 5 has at least two electrical connections + / -. Based on the high reaction temperature (T R = 800°C to 1500°C) occurring within chamber 1, it is important that the electrical connections (+ / -) of the heating element 5 are located outside chamber 1. For this reason, the heating element 5 extends through the wall 2 of chamber 1. In the feed-through region, sleeves are respectively arranged between the wall and the heating element (not shown). The wall 2 is made of a heat-insulating material, and since the device 0 has an active cooling part described later, the temperature outside chamber 1 is much lower in the region of the electrical connections + / -, which is less than about 400°C. Here, this temperature is referred to as the intermediate temperature T c .

[0074] In this lower temperature range, the electrical connections + / - are respectively connected to the first connection point 61 and the second connection point 62, and the first electrical line 71 or the second electrical line 72. The connection points 61, 62 may be in series connection (not shown), or parallel connection (shown), or a combination from both. In a three-phase system, a star connection is also possible (not shown). The first electrical line and the second electrical line 71, 72 are connected to the voltage source 8. In a three-phase system, a third electrical line to the voltage source 8 is required (not shown).

[0075] The voltage source 8 supplies the energy required for the process in the form of electricity. Preferably, all the energy required to chemically convert methane and ammonia into hydrogen cyanide and hydrogen is supplied in the form of electricity.

[0076] During operation, a voltage U obtained from the voltage source 8 is supplied to the electrical heating element via electrical lines 71, 72 and connection points 61, 62, causing a current I to flow through the electrical heating element 5. The heating element 5 converts electrical energy into thermal energy, thereby heating the surface of the heating element. This enables the reaction.

[0077] In contrast to conventional thermal heating BMA methods, the heat required for the reaction is not introduced into the chamber 1 from the outside, but is generated in-situ within the reaction space by the heating element 5.

[0078] To increase the reaction rate, a catalyst is used in chamber 1. The catalyst may contain platinum and is preferably coated on the surface of heating element 5.

[0079] The hydrogen cyanide (HCN) produced in this process is highly toxic. To prevent leakage of hydrogen cyanide, chamber 1 is surrounded by a gas-tight shell 9 with a cover structure as a double cover. The double cover 9 also functions as a heat exchanger 10 filled with a cooling fluid.

[0080] The inlet passage 3 and outlet passage 4 are respectively led to the shell 9 and sealed to the shell 9, so that the gaseous starting materials CH4 and NH3 enter the chamber 1 through the gas-tight shell 9, and the products HCN, H2, and unconverted starting materials, as well as by-products, exit the chamber 1 again.

[0081] An intermediate chamber 12 extends between the shell 9 and the chamber 1. The heating element 5 extends through the wall 2 of the chamber 1 into the intermediate chamber 12, where the electrical connections + and - of the heating element 5 are located.

[0082] The feedthrough of the heating element 5 through wall 2 is not gastight because, here, some mobility of the heating element 5 relative to wall 2 is required due to thermal expansion. Unlike shell 9, wall 2 of chamber 1 is also not gastight, which means that reaction participants from chamber 1 may enter the intermediate chamber 12. To prevent this, the intermediate chamber 12 may optionally contain a small amount of starting material and can be statically supplied with a filling gas that has a pressure difference with respect to the reaction space. The filling gas is obtained from a filling gas source 11 and is delivered to the intermediate chamber 12 via a filling gas pipeline (not shown) and connecting elements (not shown).

[0083] Similarly, the double cover 9 is supplied with cooling fluid from the cooling fluid source 13 from the inside. However, the cooling fluid is again drawn out of the shell 9, i.e., drawn out to the cooling fluid sink 14. Thus, the cooling fluid flows from its source 13 through the shell 9 to its sink 14. In this way, heat is dissipated from the double cover 9 through the cooling fluid. The double cover 9 also functions as a heat exchanger 10. Thus, the device 0 undergoes active cooling. For this purpose, a substance with good specific heat capacity, such as liquid water or liquid oil, is used as the cooling fluid. The heat dissipated to the sink 14 through the cooling fluid is the heat transferred from the metal shell of the wall 2 to the double cover 9 by thermal radiation. This heat is relatively small due to the insulation of the wall 2.

[0084] As an alternative to the double cover 9, the heat exchanger 10 can also be realized by a cooling coil wound around a shell 9 (not shown). Since the cooling fluid flows through the cooling coil, the shell 9 can be formed with a single wall.

[0085] gas pressure p of the filling gas in the intermediate chamber 12 C The reaction pressure p in chamber 1 RIf the pressure is only slightly greater than the gas pressure p, the wall 2 of chamber 1 will experience almost no mechanical load. In particular, it does not need to withstand large internal pressures. Therefore, the wall 2 can be optimized in terms of thermal insulation. Conversely, the double cover 9 is subjected to pressure loads. That is, this double cover 9, in contrast to the wall 2 of chamber 1, is subjected to gas pressure p C It needs to withstand the internal pressure corresponding to the difference between the ambient pressure p0 and the shell 9. The shell 9 does not experience a very strong thermal load (temperature T of the cooling fluid inside the shell 9). i (In many cases, the temperature is below 100°C), where pressure safety can be achieved much more easily. Furthermore, the double cover 9 may be made of steel, which is mechanically more durable than the insulating material including the wall 2 of the chamber 1, although it does not have thermal insulation properties. Thus, in the apparatus according to the present invention, the wall 2 performs only the function of thermal insulation, while the functions of gastightness and pressure holding are taken over by the shell 9.

[0086] A further important aspect of the apparatus according to the present invention is the orientation of the heating element 5 with respect to the gravitational acceleration g and the main flow direction V of the reactants.

[0087] The main flow direction V extends from the inlet to the outlet through Chamber 1. Along this main flow direction V, the starting materials CH4 and NH3 flow into Chamber 1, and the products HCN and H2, as well as unconverted starting materials and by-products, flow out of Chamber 1 again.

[0088] In the embodiment of the apparatus according to the present invention shown in Figure 1, the heating element 5 is arranged laterally with respect to the main flow direction V, so that the longitudinal axis H of the heating element 5 forms a 90° angle φ with respect to the main flow direction V.

[0089] This has the advantage that each heating element 5 is subjected to only a small temperature difference. In other words, the reaction temperature T RThe temperature is not the same everywhere within chamber 1, but varies along the main flow direction V. This is because, on the one hand, the temperature changes along the main flow direction based on the progress of the transformation. On the other hand, the heating element 5 can be adjusted to different temperatures via the power supply to give the reaction along the main flow direction an optimal temperature profile. The power supply, and ultimately the temperature, can also be set in relation to the magnitude of the electricity obtained from the voltage source 8.

[0090] When the heating elements 5 are positioned laterally with respect to the main flow direction V, the temperature profile at the location of each heating element is approximately constant. Therefore, the thermal expansion of the heating elements is constant along their entire length, thereby improving the stability of the heating elements.

[0091] In the embodiment of the apparatus of the present invention shown in Figure 1, the main flow direction V is positioned vertically, opposite to the acceleration due to gravity g. Therefore, preferably, flow is directed from bottom to top through the chamber 1, and other flow directions are similarly possible if required by the structural shape.

[0092] If the main flow direction V extends vertically, and the longitudinal axis of the heating element 5 extends 90° laterally with respect to it, then the longitudinal axis H of the heating element 5 optimally extends horizontally.

[0093] In the embodiment shown in Figure 1, the device 0 has a cylindrical heating element 5 with its longitudinal axis H positioned horizontally.

[0094] If heating elements of other structural shapes are selected, their orientation should be appropriately chosen within the chamber.

[0095] Therefore, Figure 2 shows a second embodiment of the apparatus 0 according to the present invention, in which case the heating resistor 5 is U-shaped. In order to orient the U-shaped heating element along the isotherm, the legs of the U should be oriented laterally with respect to the main flow direction V and should be positioned at the same location along the main flow direction V within the chamber 1. In the case of a vertical main flow direction V, the legs of the U may be at the same height level (not shown). In this respect, both the U-shaped heating element and the cylindrical heating element extend along the main resistance axis H which is positioned laterally with respect to the main flow direction V. The legs of the U extend parallel to both sides of the main resistance axis H which corresponds to the axis of symmetry of the U. In the case of a cylindrical heating element (Figure 1), the longitudinal axis corresponds to the main resistance axis H.

[0096] I would like to summarize the essential aspects of this invention once again: The fundamental problem of the present invention is to provide an electrically heated reactor for the production of hydrogen cyanide and other nitriles that allows for distinct temperature profiles and can be adequately constructed with inexpensive, standard components. The essential component of the apparatus 0 according to the present invention is a chamber 1 made of gas-permeable insulating material, representing the actual reaction space. An electrical heating element 5 protrudes into the chamber 1, thereby allowing the chamber 1 to be heated from the inside by the heating element 5. The electrical connections of the heating element are located outside the reaction space, but inside the surrounding shell. That is, unlike the BMA method practiced industrially, heat is generated within the reaction space rather than being transported from the outside into the reaction space. Heat generation is achieved by the conversion of electrical energy by the heating element 5 according to the principle of resistance heating. To ensure the gastightness of the apparatus 0, a shell 9 is provided that gastightly surrounds the chamber 1.

[0097] experiment The following experiments demonstrate the advantageous effects of the apparatus according to the present invention.

[0098] These experiments were simulations using computational fluid dynamics (CFD). Ansys Fluent (version Fluent 2021R2) software was used.

[0099] The reaction space is rectangular and contains approximately 900 heating elements.

[0100] In all three experiments, the synthesis gas was 2.8 bar (2.8 * 10 5 The gas consists of ammonia and methane in a molar ratio of 1.1:1 at an absolute pressure of Pa. The gas is preheated to 200°C, and the starting material amount is 1440 kg / h. The simulation is performed under adiabatic conditions with a heating output of 4.1 MW.

[0101] The simulation results are illustrated in graphs in Figures 3-6: Figure 3 shows the temperature along the central heating element in the reactor when the heating element is oriented horizontally and vertically. Figure 4 shows the temperature progression across the reactor. Figure 5 shows the progress of the yield. Figure 6 shows the progression of the output profile in Experiment 3.

[0102] Experiment 1 (Vertical orientation of heating element - constant output) The heating element is positioned vertically, i.e., parallel to the acceleration due to gravity, and the flow through the reactor is horizontal. The output of the heating element is 38 kW / m² in the example described here. 2 It is being done.

[0103] Based on thermal buoyancy, a temperature gradient of 500-700K may exist along the heating element (see dashed line in Figure 3), which could adversely affect the lifespan of the heating element.

[0104] The temperature progression across the reactor is shown by the dashed line in Figure 4. The yield of HCN based on NH3 is illustrated by the dashed line in Figure 5. The yield is 72%.

[0105] Experiment 2 (Horizontal orientation of heating element - constant output) Maintaining the operating parameters from Experiment 1, i.e., the output of the heating element remained constant at 38 kW / m². 2However, the heating element is positioned horizontally, and the reactor is designed to flow from bottom to top.

[0106] Based on the horizontal arrangement of the heating elements, a relatively uniform temperature is maintained above each heating element, which may have a favorable impact on the lifespan of the heating elements (see solid line in Figure 3).

[0107] The temperature progression is shown by the dotted line in Figure 4. The yield of HCN based on NH3 is illustrated by the dotted line in Figure 5. The maximum gas temperature exceeds 1400°C, which may adversely affect the lifetime of the heating element. The yield of HCN based on NH3 is 80%.

[0108] Experiment 3 (Horizontal orientation of heating elements with fluctuating output profiles) The heating element is positioned horizontally, and the reactor flows from bottom to top. The output of the heating element is controlled via a profile, with an output of 4-60 kW / m². 2 It fluctuates within this range. The evolution of the output profile is illustrated in Figure 6.

[0109] Based on the horizontal arrangement of the heating elements, a nearly uniform temperature is maintained above each heating element, which may favorably influence the lifespan of the heating elements. The temperature progression along the rod length is illustrated by the solid line in Figure 3.

[0110] The temperature progression throughout the reactor is illustrated in Figure 4 (solid line). The maximum gas temperature is in the range of 1300°C. Based on the output profile which decreases towards the end (Figure 6), the temperature also decreases again towards the end of Experiment 3 (solid line in Figure 4).

[0111] The yield of HCN based on NH3 is illustrated by the solid line in Figure 5. The yield of HCN based on NH3 is 83%, which is therefore higher than that of experiments 1 and 2.

[0112] conclusion When the heating element is positioned horizontally and a variable output profile is provided, the maximum yield can be achieved. Furthermore, the horizontal heating element is subjected to less temperature stress. [Explanation of symbols]

[0113] 0 equipment 1 Chamber 2 walls 3 Inflow channel 4 Outflow channel 5 heating element 61 First connection point 62 Second connection point 71 First Electrical Line 72 Second Electrical Line 8. Voltage source 9. Shell (formed as a double cover) 10 Heat exchanger 11. Gas source for filling 12. Intermediate Room 13 Cooling fluid source 14 Cooling fluid sink + First electrical connection - Second electrical connection Pt platinum catalyst T R Reaction temperature T c intermediate temperature T i Cooling fluid temperature p R reaction pressure p C Counter-pressure p0 peripheral pressure CH4 methane NH3 Ammonia HCN (hydrogen cyanide) H2 hydrogen O2 (Oxygen) g gravitational acceleration V Main flow direction H Main resistance axis φ angle

Claims

1. An apparatus (0) for producing at least one product gas from at least one starting material gas, in particular an apparatus (0) for producing nitrile, a) A chamber (1) having a gas-permeable and insulating wall (2), an inlet (3) for the starting material gas, an outlet (4) for the product gas, and a main flow direction (V) extending from the inlet (3) to the outlet (4), b) A gas-tight shell (9) surrounding the chamber (1), the shell (9) through which the inlet passage (3) and the outlet passage (4) are connected, c) An intermediate chamber (12) is located between the chamber (1) and the shell (9), surrounding the chamber (1) and being surrounded by the shell (9), d) At least one electrical heating element (5) having a wall (2) that extends through the chamber (1) and is penetrated at least once, and having at least two electrical connections (+, -) located inside the intermediate chamber (12) and outside the chamber (1), e) A voltage source (8) located outside the shell (9), which is connected to the first electrical connection (+) of the heating element (5) via at least a first electrical line (71), and connected to the second electrical connection (-) of the heating element (5) via a second electrical line (72), and the first and second electrical lines (71, 72) are conductive to the shell (9), f) At least one connecting element for a filling gas source (11) located outside the shell (9), which is fluid-guided to the intermediate chamber (12) via a filling gas pipeline, thereby enabling the supply of filling gas from the filling gas source (11) to the intermediate chamber (12), g) The catalyst and the catalyst placed in the chamber (1) A device (0) comprising:

2. The apparatus (0) according to claim 1, characterized in that it is provided with at least one heat exchanger (10) located outside the gas-tight shell (9) and connected to the shell (9) by heat conduction.

3. The apparatus (0) according to claim 2, characterized in that the heat exchanger (10) contains a cooling fluid, and the heat exchanger (10) is fluid-guided to a cooling fluid source (13) via a feed path and to a cooling fluid sink (14) via a return path.

4. The apparatus (0) according to claim 3, characterized in that the gas-tight shell (9) has a cover structure as a double cover (9), and the cooling fluid can be guided at least partially inside the double cover (9).

5. The apparatus (0) according to claim 3, wherein the heat exchanger (10) comprises a cooling coil, the cooling coil is connected to the return path via a cooling fluid guide via the supply path, and is wound around the shell (9).

6. The apparatus (0) according to claim 5, characterized in that the cooling coil is formed as a tube connected to the outer surface of the gas-tight shell (9) via a thermal bridge.

7. The apparatus (0) according to claim 5, wherein the cooling coil is obtained by welding an open profile to the outer surface of the gas-tight shell (9), and the cooling fluid can be guided at least partially between the profile and the outer surface of the gas-tight shell (9).

8. The apparatus (0) according to any one of claims 3 to 7, characterized in that the cooling fluid is selected from the group consisting of the following cooling fluids: air, gaseous nitrogen, gaseous argon, gaseous water, liquid water, liquid nitrogen, liquid oil, gaseous ammonia, gaseous hydrocarbons, or mixtures thereof.

9. The apparatus (0) according to any one of claims 1 to 8, characterized in that the electrical heating element (5) has exactly two electrical connections (+, -) and extends linearly through the chamber (1).

10. The apparatus (0) according to any one of claims 1 to 8, characterized in that the electrical heating element (5) has exactly two electrical connections (+, -) and extends through the chamber (1) in a U-shape or M-shape, or the electrical heating element (5) has exactly three electrical connections and extends through the chamber in a W-shape, or a combination thereof.

11. The apparatus (0) according to claim 9 or 10, wherein the electrical heating element (5) extends through the chamber (1) along the main resistance axis (H), and the main resistance axis (H) and the main flow direction (V) form an angle (φ) that is at least 0° and at most 90°.

12. The apparatus (0) according to claim 11, characterized in that the angle (φ) is 90°.

13. The apparatus (0) according to claim 12, characterized in that the main flow direction (V) extends vertically.

14. The apparatus (0) according to claim 13, characterized in that the main flow direction (V) extends in the opposite direction to the acceleration due to gravity (g).

15. The apparatus (0) according to any one of claims 1 to 14, characterized in that it is provided with a number of electrically heated elements (5) that are electrically connected to each other in series and / or parallel.

16. The apparatus (0) according to claim 15, characterized in that the catalyst is deposited on the surface of at least one electrically heated element (5) in the form of a catalytically active coating.

17. The apparatus (0) according to claim 16, characterized in that it is provided with at least one heating element (5) that does not have a catalytically active coating.

18. The apparatus (0) according to any one of claims 1 to 14, characterized in that the heat insulating wall (2) of the chamber (1) is formed in multiple layers.

19. The apparatus (0) according to claim 18, characterized in that the thermal insulation wall (2) comprises at least two layers with respect to specific thermal conductivity.

20. The apparatus (0) according to claim 18 or 19, characterized in that an additional inner layer is provided on the wall of the chamber having a closed surface.

21. The apparatus (0) according to any one of claims 18 to 20, characterized in that the inner layer provided on the wall (2) of the chamber (1) comprises a catalytically active coating containing the catalyst or a catalytically activatable coating.

22. The apparatus (0) according to any one of claims 1 to 21, characterized in that the chamber (1) has a cross-section of a shape different from a circle in the main flow direction (V).

23. The apparatus (0) according to any one of claims 1 to 22, characterized in that the heating elements (5) are arranged in a sequence, one in front of the other, or offset from each other, when viewed in the main flow direction (V).

24. The apparatus (0) according to claim 22 or 23, characterized in that at least one heating element (5) is provided, which is located in close proximity to the wall (2), extends parallel to the wall (2), and is not connected to at least one of the two electrical lines (71, 72).

25. The apparatus (0) according to any one of claims 1 to 24, characterized in that the catalyst contains platinum (Pt).

26. The apparatus (0) according to any one of claims 1 to 25, characterized in that the heating element (5) comprises a core made of silicon carbide or molybdenum silicide, a protective coating is applied to the core, and a catalytically active coating is applied to the protective coating.

27. A method for producing nitriles, particularly hydrogen cyanide (HCN), a) A step of preparing the apparatus (0) according to any one of claims 1 to 26, b) At least ammonia (NH ３ ) and gaseous hydrocarbons, preferably methane (CH ４ A step of supplying a starting material gas mixture containing ) to the inlet passage (3), c) A step of supplying the current obtained from the voltage source (8) to the heating element (5), d) The step of removing the product gas mixture containing at least one formed nitrile, preferably hydrogen cyanide (HCN), from the outlet passage (4), and e) Supply a filling gas to the intermediate chamber (12), thereby reducing the reaction pressure (p) generated in the chamber (1) within the intermediate chamber. Ｒ Gas pressure (p) greater than or equal to Ｃ ) to cause, step Methods that include...

28. The aforementioned starting material gas mixture is methane (CH4 ３ The method according to claim 27, characterized in that it contains ) and thereby produces hydrocyanic acid (HCN).

29. The aforementioned starting material gas mixture contains oxygen (O ２ ) is additionally contained, thereby allowing the starting material gas mixture to be assigned an oxygen limit concentration (SGK) above which the starting material gas mixture becomes flammable, and the oxygen concentration (KO) in the starting material gas mixture ２ The method according to claim 27 or 28, characterized in that ) is less than the oxygen limit concentration (SGK).

30. At least 1 ＊ 10 ５ Absolute pressure of Pa and maximum 5 ＊ 10 ５ The reaction pressure (p Ｒ ) generated in the chamber (1) and absolute pressure of Pa, the method according to claim 27, 28 or 29

31. The method according to any one of claims 27 to 30, characterized in that it is carried out continuously so as to generate a flow through the chamber (1) along the main flow direction (V) extending from the inlet passage (3) to the outlet passage (4), the heating element (5) extends through the chamber (1) along the main resistance axis (H), and the main flow direction (V) extends perpendicular to the main resistance axis (H) of the heating element (5).

32. At least one reaction temperature (T) generated in the chamber (1) is greater than 800°C and less than 1500°C. Ｒ ) is carried out in the intermediate chamber (12) at an intermediate temperature of less than 400°C (T ｃ The method according to any one of claims 27 to 31, wherein the occurrence of ) occurs.

33. The method according to any one of claims 30 to 33, characterized in that the filling gas is selected from the group consisting of the following filling gases: gaseous nitrogen, gaseous hydrogen, gaseous hydrocarbons, gaseous ammonia, or mixtures thereof.

34. The method according to any one of claims 27 to 33, wherein an apparatus (0) according to any one of claims 3 to 26 is prepared, the cooling fluid is continuously obtained from the cooling fluid source (13), the cooling fluid is continuously supplied to the heat exchanger (10), the cooling fluid is continuously withdrawn from the heat exchanger (10), and the temperature of the cooling fluid in the supply path is lower than that in the return path.

35. The method according to claim 34, characterized in that the cooling fluid is a mixture of starting material gases, the cooling fluid sink is the chamber (1), and thereby the mixture of starting material gases is preheated in the heat exchanger (10).

36. Use of the apparatus (0) according to any one of claims 1 to 26 for the purpose of providing a negative control output for the purpose of stabilizing an electrical system.

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