Reactor for preparing hydrogen cyanide

Abstract

Provided in the present invention is a reactor for preparing hydrogen cyanide. The reactor comprises a reaction zone and a cooling zone, wherein a tapered tube plate is provided at the lower end of a shell in the reaction zone; an upper cooling shell in the cooling zone covers the periphery of a lower shell in the reaction zone; and a steam outlet is provided at the position on the upper cooling shell in the cooling zone that is staggered with the shell in the reaction zone. By using the above arrangement, a specific gas-liquid phase distribution is formed in the upper space in the cooling zone, ensuring that high-temperature elements (the tops of the tapered tube plate and a heat exchange tube) come into full contact with a coolant, and keeps away from a coolant high-temperature gas phase region as far as possible; and the stable operation of the device is facilitated.

Description

A reactor for preparing hydrogen cyanide Technical Field

[0001] The invention belongs to the field of chemical equipment and relates to a reactor for preparing hydrogen cyanide. Background Art

[0002] The Angstrom process is the primary method for producing hydrogen cyanide. The traditional Angstrom process uses air as a feedstock, and the nitrogen content in the exhaust gas can reach approximately 55-75%, resulting in high subsequent separation costs and affecting hydrocyanic acid production capacity.

[0003] The pure oxygen method uses pure oxygen (oxygen-enriched air) instead of air for the ammonia oxidation reaction. The oxygen content in oxygen-enriched air is generally between 70% and 90%. Compared to the traditional Ansler process, the pure oxygen method can more than double the hydrocyanic acid production capacity using the same equipment. Therefore, the pure oxygen method not only increases production capacity but also reduces production costs, offering excellent economic benefits.

[0004] Hydrogen cyanide easily reacts with rust (Fe2O3) at high temperatures, and the reaction equation is:

[0005] 2Fe2O3+3HCN→2Fe+3CO+3NO+0.5H2

[0006] Compared to the Angleworth process, the pure oxygen process has a different thermal balance and places distinct equipment requirements. The higher pressures and temperatures within the reaction chamber make existing reactors insufficient for the pure oxygen process to produce hydrogen cyanide. Therefore, a new hydrogen cyanide reactor design is needed to meet the production process requirements. Summary of the Invention

[0007] The present invention aims to provide a reactor for preparing hydrogen cyanide, comprising a reaction zone and a cooling zone. The reactor comprises a conical tube sheet at the lower end of the reaction zone shell, an upper cooling shell of the cooling zone wraps around the outer periphery of the lower shell of the reaction zone, and a steam outlet is provided on the upper cooling shell of the cooling zone at a position intersecting with the reaction zone shell. With this arrangement, a specific gas-liquid phase distribution is formed in the upper space within the cooling zone, ensuring that high-temperature components (conical tube sheet, top of heat exchange tube) are in full contact with the coolant and are kept as far away as possible from the high-temperature gas phase zone of the coolant. This arrangement is also conducive to the stable operation of the device under a pure oxygen process operating environment.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides a reactor for preparing hydrogen cyanide, comprising: a shell; the shell comprises a reaction zone located at the upper portion and a cooling zone located at the lower portion;

[0010] A conical tube plate is provided at the lower end of the reaction zone shell. The upper cooling shell of the cooling zone wraps the outer periphery of the lower shell of the reaction zone. A steam outlet is provided on the upper cooling shell of the cooling zone at a position intersecting with the reaction zone shell.

[0011] The term "wrapping" herein refers to sealing between the upper end portion of the upper cooling shell and the outer wall of the lower shell of the reaction zone.

[0012] The pure oxygen method for preparing hydrogen cyanide is generally carried out at high temperatures, with reaction temperatures exceeding 1100°C, placing high demands on reaction equipment. In the reactor described herein, a tapered tube sheet is disposed between the reaction zone and the cooling zone. The upper cooling shell of the cooling zone wraps around the outer periphery of the lower shell of the reaction zone. A steam outlet is provided on the upper cooling shell of the cooling zone at a position intersecting with the reaction zone shell. During operation of the device, a specific gas-liquid phase distribution is formed in the space above the cooling zone, ensuring that high-temperature components (tapered tube sheets, tops of heat exchange tubes) are in full contact with the coolant and are kept as far away as possible from the coolant's high-temperature gas phase zone. This facilitates improved operational stability of the device.

[0013] The device of the present invention adopts the above structure. Compared with the reactor with a shell equal diameter structure, it retains a certain gas phase space in the cooling zone while effectively protecting the high-temperature components and ensuring the stable reaction and cooling process.

[0014] Preferably, the equivalent diameter of the upper cooling shell of the cooling zone is larger than the equivalent diameter of the lower shell of the reaction zone; here, the equivalent diameter of the upper cooling shell of the cooling zone refers to the inner diameter, and the equivalent diameter of the lower shell of the reaction zone refers to the outer diameter.

[0015] Preferably, the semi-cone angle of the conical tube plate is selected from 65° to 80°, such as 70° or 75°, and preferably 75° to 80°.

[0016] In the present invention, the use of a tapered tube sheet is beneficial to improving the load-bearing capacity of the tube sheet. Controlling the semi-cone angle of the tapered tube sheet within the above-mentioned range can reduce the thickness of the tapered tube sheet, enhance the cooling effect of the coolant, prevent excessive local thermal stress, and improve the stability of the device.

[0017] Preferably, the shell of the cooling zone includes an upper cooling shell and a lower cooling shell; the upper cooling shell and the lower cooling shell are connected by a transition section;

[0018] The lower cooling shell is provided with a coolant inlet;

[0019] The conical tube plate is located in the upper cooling shell of the cooling zone; the equivalent diameter of the upper cooling shell is a first diameter; the equivalent diameter of the lower cooling shell is a second diameter; the first diameter is greater than the second diameter.

[0020] Here, the first diameter and the second diameter both refer to the inner diameter.

[0021] In the present invention, the shell of the cooling zone is set with the above-mentioned dimensions, which increases the gas phase space at the top of the cooling zone and ensures that the cooling operation is carried out stably.

[0022] Preferably, the cooling zone comprises a gas phase zone at the top and a liquid phase zone at the bottom, and the steam outlet is connected to the gas phase zone.

[0023] Preferably, a thermometer for monitoring the temperature of the gas phase region is provided on the housing of the cooling zone. The thermometer can be selected from a temperature sensor.

[0024] In the present invention, the cooling zone is used to cool down the reaction products in the reaction zone. The above arrangement is used to prevent the metal components from being damaged by temperature difference stress due to excessively high local temperatures.

[0025] Preferably, the material of the shell corresponding to the reaction zone is selected from stainless steel;

[0026] The material of the conical tube plate is selected from stainless steel.

[0027] Conventional hydrogen cyanide production equipment generally uses carbon steel. Hydrogen cyanide easily reacts with rust (Fe2O3) at high temperatures. The reaction equation is:

[0028] 2Fe2O3+3HCN→2Fe+3CO+3NO+0.5H2

[0029] Therefore, it is difficult to apply to the production of hydrogen cyanide by the pure oxygen method. The present invention has found through research that the use of stainless steel instead of carbon steel, combined with the above-mentioned specific structural setting of the present invention, can effectively avoid the occurrence of the reaction between rust and hydrogen cyanide products.

[0030] The present invention uses stainless steel instead of carbon steel to solve the problem of rust reacting with hydrogen cyanide and improve the corrosion resistance of the equipment. At the same time, the present invention prefers the above-mentioned specific stainless steel material, which has better corrosion resistance under high temperature and the presence of hydrogen cyanide products while maintaining better heat transfer effect.

[0031] Preferably, a heat exchange tube is provided in the cooling zone, one end of the heat exchange tube is connected to the hole of the tapered tube sheet; an insulating sleeve is provided in the heat exchange tube at a position corresponding to the hole of the tapered tube sheet;

[0032] The upper end of the thermal insulation sleeve extends out of the upper surface of the conical tube plate, and the lower end of the thermal insulation sleeve extends out of the lower surface of the conical tube plate.

[0033] Preferably, the heat exchange tubes are in a tube bundle structure.

[0034] Preferably, one end of the heat exchange tube connected to the conical tube sheet extends out of the conical tube sheet, which is beneficial to improving the stability of the connection between the conical tube sheet and the heat exchange tube.

[0035] Preferably, the insulating sleeve is made of ceramic.

[0036] In the present invention, one end of the insulation sleeve is located in the heat exchange tube, and the other end is fixedly connected to the insulation layer on the surface of the tapered tube sheet, thereby protecting the connection between the heat exchange tube and the tapered tube sheet to avoid corrosion or structural damage at high temperatures.

[0037] Preferably, a heat insulating material is provided inside the heat exchange tube and between the heat exchange tube and the heat insulating sleeve, and the heat insulating material is selected from ceramic fiber paper.

[0038] The present invention uses ceramic insulation sleeves and ceramic fiber paper to insulate the heat exchange tubes, reducing the impact of high temperature on the ends of the heat exchange tubes and increasing the stability of the equipment structure; and the preferred ceramic material is beneficial to further improve the stability of the connection between the reaction zone and the cooling zone.

[0039] Preferably, a ceramic refractory brick layer is provided inside the shell corresponding to the reaction zone;

[0040] In the reaction zone, a double-layer insulation layer is provided on the upper surface of the conical tube plate, comprising a first insulation layer adjacent to the conical tube plate surface and a second insulation layer located above the first insulation layer;

[0041] The first insulation layer is a corundum casting layer, and the second insulation layer is a ceramic refractory brick layer;

[0042] The double-layer insulation layer is provided with an opening at a position corresponding to the insulation sleeve, and the opening is used to connect the reaction zone and the insulation sleeve.

[0043] Preferably, the upper end opening of the thermal insulation sleeve is located in the first thermal insulation layer.

[0044] The present invention adopts the above-mentioned specific double-layer insulation layer, which has a better insulation effect compared to the single-layer insulation layer, and the end of the insulation sleeve is connected to the first insulation layer, and the connection has better structural stability.

[0045] Preferably, the upper shell of the reaction zone is provided with a feed inlet; and a gas distributor is provided below the feed inlet.

[0046] Preferably, in the reactor, the area between the feed port and the gas distributor is the gas inlet area.

[0047] Preferably, the gas distributor comprises at least one porous plate;

[0048] The purpose of providing a gas distributor above the reaction zone in the present invention is to uniformly distribute the feed gas entering the reactor through the gas input pipeline to the reaction zone. The specific form of the gas distributor can be several porous plates, a combination of a porous plate and a wire mesh, or other forms of gas distributor.

[0049] Preferably, the gas distributor comprises at least two porous plates, and the porosity and pore size of the upper porous plate are preferably larger than those of the lower porous plate.

[0050] Preferably, the gas distributor includes a first porous plate and a second porous plate located below the first porous plate, and the pore size and porosity of the first porous plate are larger than those of the second porous plate.

[0051] Preferably, the pore size of the first porous plate is 100 mm to 250 mm, for example, 150 mm or 200 mm;

[0052] The pore size of the second porous plate is 6 mm to 20 mm, for example, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm or 18 mm.

[0053] Preferably, a vertical plate is provided between the first porous plate and the second porous plate for dividing the space between the first porous plate and the second porous plate; the middle rectangular vertical plate assists in gas distribution and supports the upper and lower porous plates at the same time.

[0054] The present invention adopts the above-mentioned gas distributor, that is, the pore size and porosity are differentially distributed. Compared with a single porous plate structure, it can achieve step-by-step distribution of gas, and the distribution effect is significantly improved.

[0055] Preferably, a tube sheet is provided at the bottom of the cooling zone, the tube sheet being connected to the ends of the heat exchange tubes; a tube box is provided below the tube sheet, the tube box being provided with a discharge port, and a manhole is provided on the tube box.

[0056] Preferably, a catalyst layer is provided below the gas distributor in the reaction zone;

[0057] Preferably, an ignition port is provided on the shell at the upper portion of the reaction zone. The reactor is provided with a plurality of burners through the ignition port, and a plurality of ignition ports are provided along the circumference of the shell at the top of the reaction zone; the ignition port is provided around the feed port; the burner is obliquely provided in the shell through the ignition port, and the end of the burner is provided below the gas distributor. The object of the present invention is to provide a reactor that can meet the production process requirements of hydrogen cyanide prepared by the pure oxygen method, wherein the high-performance insulation system includes a ceramic refractory brick layer located on the wall of the shell of the reaction zone, a double-layer insulation layer located on the upper surface of the conical tube plate, and an insulation sleeve and ceramic fiber paper located in the heat exchange tube; it covers the reaction zone and the conical tube plate and heat exchange tube area; the purpose is to prevent the high temperature from reducing the strength and corrosion resistance of stainless steel and failing to meet the process requirements.

[0058] In the present invention, the insulation material selected for the high-performance insulation system has a sufficiently low thermal conductivity and meets the required formability requirements. In a preferred embodiment, ceramic refractory bricks are used for thermal insulation of the reaction zone shell walls, ceramic refractory bricks and corundum castables are used for thermal insulation of the tube bundle tubesheets, and ceramic insulation sleeves and ceramic fiber paper are used for thermal insulation of the heat exchange tube holes.

[0059] The present invention provides an operating method for the above-mentioned reactor for preparing hydrogen cyanide, comprising: reactant raw gas enters the reactor through a feed port via at least one gas input pipeline, reacts in a reaction zone after passing through a gas distributor, and the reaction product enters a pipe box after heat exchange with an external coolant through a heat exchange pipe in a cooling zone, and is then discharged from the reactor through at least one output pipeline.

[0060] The coolant in the present invention can be selected from circulating water or cooling water.

[0061] In the present invention, the cross section of the reactor can be circular, rectangular or other shapes, and is preferably circular. The volume of the reactor vessel is determined according to the expected production capacity of the reactor.

[0062] The reactor of the present invention can meet the production process requirements of preparing hydrogen cyanide by pure oxygen method.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] In the present invention, the reactor includes a reaction zone and a cooling zone, the lower end of the reaction zone shell is provided with a tapered tube sheet, the upper cooling shell of the cooling zone wraps the outer periphery of the lower shell of the reaction zone, and a steam outlet is provided on the upper cooling shell of the cooling zone at a position intersecting with the reaction zone shell; with the above arrangement, during the operation of the device, a specific gas-liquid phase distribution is formed in the upper space within the cooling zone, ensuring that the high-temperature components (tapered tube sheet, top of the heat exchange tube) are in full contact with the coolant and as far away as possible from the high-temperature gas phase zone of the coolant; this is conducive to the stable operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] FIG1 is a schematic structural diagram of a reactor for preparing hydrogen cyanide in Example 1 of the present invention;

[0066] FIG2 is a schematic structural diagram of the connection between the tapered tube sheet and the heat exchange tube in Example 1 of the present invention (a partial view of area A in FIG1 );

[0067] FIG3 is a schematic structural diagram of a gas distributor according to an embodiment of the present invention;

[0068] 1-shell, 2-reaction zone, 20-feed port, 21-gas distributor, 22-gas inlet zone, 210-first porous plate, 211-second porous plate, 212-rectangular vertical plate, 3-cooling zone, 4-conical tube sheet, 5-steam outlet, 50-coolant inlet, 6-heat exchange tube, 60-insulating sleeve, 61-insulating material, 7-ceramic refractory brick layer, 8-first insulation layer, 9-second insulation layer, 90-pipe box, 91-discharge port, 92-ignition port, 93-thermometer. DETAILED DESCRIPTION

[0069] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0070] Example 1

[0071] This embodiment provides a reactor for preparing hydrogen cyanide, as shown in FIG1 , comprising: a shell 1 ; the shell 1 contains a reaction zone 2 located at the upper portion and a cooling zone 3 located at the lower portion;

[0072] A conical tube sheet 4 is provided at the lower end of the reaction zone shell. The upper cooling shell of the cooling zone 3 wraps around the outer periphery of the lower shell of the reaction zone. A steam outlet 5 is provided on the upper cooling shell of the cooling zone at a position intersecting with the reaction zone shell.

[0073] The semi-cone angle of the conical tube plate is 78°;

[0074] The shell of the cooling zone 3 includes an upper cooling shell and a lower cooling shell; the upper cooling shell and the lower cooling shell are connected by a transition section;

[0075] The lower cooling shell is provided with a coolant inlet 50;

[0076] The conical tube sheet is located in the upper cooling shell of the cooling zone;

[0077] The diameter of the upper cooling shell is 3730 mm; the diameter of the lower cooling shell is 2790 mm.

[0078] The cooling zone comprises a gas phase zone at the top and a liquid phase zone at the bottom, and the steam outlet is connected to the gas phase zone;

[0079] A heat exchange tube 6 is provided in the cooling zone. As shown in FIG2 , one end of the heat exchange tube is connected to the hole of the tapered tube sheet. An insulating sleeve 60 is provided in the heat exchange tube 6 at a position corresponding to the hole of the tapered tube sheet. The upper end of the insulating sleeve 60 extends beyond the upper surface of the tapered tube sheet, and the lower end of the insulating sleeve extends beyond the lower surface of the tapered tube sheet.

[0080] The thermal insulation sleeve is made of ceramic with a thermal conductivity of less than 1W / (m·K);

[0081] Located inside the heat exchange tube, a heat insulating material 61 is provided between the heat exchange tube 6 and the heat insulating sleeve 60, and the heat insulating material 61 is selected from ceramic fiber paper;

[0082] A ceramic refractory brick layer 7 is provided inside the shell corresponding to the reaction zone;

[0083] In the reaction zone, a double-layer insulation layer is provided on the upper surface of the conical tube sheet, comprising a first insulation layer 8 adjacent to the conical tube sheet surface and a second insulation layer 9 located above the first insulation layer;

[0084] The first insulation layer is a corundum casting layer, and the second insulation layer is a ceramic refractory brick layer;

[0085] The double-layer insulation layer is provided with an opening at a position corresponding to the insulation sleeve, and the opening is used to connect the reaction zone and the insulation sleeve;

[0086] The upper end opening of the thermal insulation sleeve is located in the first thermal insulation layer.

[0087] A tube sheet is provided at the bottom of the cooling zone, and the tube sheet is connected to the ends of the heat exchange tubes; a tube box 90 is provided below the tube sheet, and a discharge port 91 is provided on the tube box.

[0088] An ignition port 92 is provided on the shell at the upper part of the reaction zone; a plurality of ignition ports 92 are provided along the circumference of the top of the shell 1; the ignition ports 92 are arranged around the feed port 20; the burner is arranged obliquely in the shell 1 through the ignition port 92, and the end of the burner is arranged below the gas distributor 21.

[0089] A thermometer 93 for monitoring the temperature of the gas phase region is provided on the shell of the cooling region.

[0090] Example 2

[0091] As shown in FIG1 , in this embodiment, a feed port 20 is provided on the upper shell of the reaction zone; and a gas distributor 21 is provided below the feed port 20 .

[0092] In the reactor, the area between the feed port and the gas distributor is the gas inlet area 22 .

[0093] As shown in FIG3 , the gas distributor includes a first porous plate 210 and a second porous plate 211 located below the first porous plate; the aperture of the first porous plate is 200 mm; the porosity is 37%; the aperture of the second porous plate is 10 mm;

[0094] A rectangular vertical plate 212 is provided between the first porous plate and the second porous plate. The height of the rectangular vertical plate is 500 mm, dividing the cross section of the reactor container into several 500 mm×500 mm areas.

[0095] Application examples:

[0096] The raw gas enters the reactor through the gas input pipeline via the feed port, is evenly distributed through the gas inlet area and gas distributor, enters the reaction zone, and reacts through ignition catalysis. The reaction product then passes through the heat exchange tube bundle, where it is cooled by heat exchange with the circulating water between the tube bundles, reducing the temperature from approximately 1170°C to approximately 350°C. The product then enters the pipe box and is discharged through the outlet through the output pipeline.

[0097] The use of the reactor of the present invention reduces the decomposition of HCN in the reaction synthesis gas and improves the product yield, which is increased by 10-30% compared with the traditional carbon steel reactor (yield of 40-50%); reduces the frequency of shutdown and maintenance, and extends the internal parts replacement cycle by 1-3 months compared with 3-6 months for traditional reactors, thereby increasing the service life of the equipment and ensuring stable operation of the device.

[0098] During the application of the reactor in this application example, the reactor is made of stainless steel. During the operation of the device, no rust reacts with the hydrogen cyanide product. The device has good heat transfer effect, meeting the cooling requirements of the reaction product. The device operates stably at high temperatures and can meet the production process requirements of the pure oxygen method for preparing hydrogen cyanide.

[0099] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A reactor for preparing hydrogen cyanide, characterized in that, Comprising: A housing; Inside the housing, there is a reaction zone located in the upper part and a cooling zone located in the lower part; At the lower end of the housing of the reaction zone, a conical tube sheet is provided. The upper cooling housing of the cooling zone wraps the outer periphery of the lower housing of the reaction zone. At the position where the upper cooling housing of the cooling zone intersects with the housing of the reaction zone, a vapor outlet is provided.

2. The reactor according to claim 1, characterized in that, The half-cone angle of the conical tube sheet is selected from 65° to 80°, preferably 75° to 80°.

3. The reactor according to claim 1, characterized in that, The housing of the cooling zone includes an upper cooling housing and a lower cooling housing; the upper cooling housing and the lower cooling housing are connected through a transition section; A coolant inlet is provided on the lower cooling housing; The conical tube sheet is located inside the upper cooling housing of the cooling zone; The equivalent diameter of the upper cooling housing is the first diameter; the equivalent diameter of the lower cooling housing is the second diameter; the first diameter is greater than the second diameter.

4. The reactor according to claim 1, characterized in that, Inside the cooling zone, there is a gas phase zone located in the upper part and a liquid phase zone located in the lower part, and the vapor outlet communicates with the gas phase zone.

5. The reactor according to claim 1, characterized in that, The material of the housing corresponding to the reaction zone is selected from stainless steel; The material of the conical tube sheet is selected from stainless steel.

6. The reactor according to claim 1, wherein, Heat exchange tubes are provided inside the cooling zone. One end of the heat exchange tube is connected to the pore passage of the conical tube sheet; an adiabatic sleeve is provided at the position corresponding to the pore passage of the conical tube sheet inside the heat exchange tube; The upper end of the adiabatic sleeve extends out of the upper surface of the conical tube sheet, and the lower end of the adiabatic sleeve extends out of the lower surface of the conical tube sheet; Preferably, the end of the heat exchange tube connected to the conical tube sheet extends out of the conical tube sheet.

7. The reactor according to claim 6, characterized in that, The material of the adiabatic sleeve is ceramic; An adiabatic material is provided between the heat exchange tube and the adiabatic sleeve, and the adiabatic material is selected from ceramic fiber paper; Preferably, a ceramic refractory brick layer is provided inside the housing corresponding to the reaction zone; Preferably, inside the reaction zone, a double-layer adiabatic layer is provided on the upper surface of the conical tube sheet, including a first adiabatic layer adjacent to the surface of the conical tube sheet and a second adiabatic layer located above the first adiabatic layer; Preferably, the first adiabatic layer is a corundum casting layer, and the second adiabatic layer is a ceramic refractory brick layer; Preferably, an opening is provided at the position of the double-layer adiabatic layer corresponding to the adiabatic sleeve, and the opening is used to communicate the reaction zone and the adiabatic sleeve; Preferably, the upper end opening of the adiabatic sleeve is located inside the first adiabatic layer.

8. The reactor according to claim 1, wherein, An inlet is provided on the upper housing of the reaction zone; a gas distributor is provided below the inlet; The gas distributor includes at least two porous plates. The porosity and pore diameter of the porous plate located above are larger than those of the porous plate located below.

9. The reactor according to claim 8, wherein, The gas distributor includes a first porous plate and a second porous plate located below the first porous plate; The pore diameter of the first porous plate is 100 mm to 250 mm; The pore diameter of the second porous plate is 6 mm to 20 mm.

10. The reactor according to claim 1, characterized in that, A tube sheet is provided at the bottom of the cooling zone, and the tube sheet connects the end of the heat exchange tube; a tube box is provided below the tube sheet, and an outlet is provided on the tube box.

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