Method and apparatus for nitrile production using controlled spray liquid input pressure

Abstract

The present invention relates to a method and apparatus for nitrile production using a controlled spray liquid input pressure. The production method atomizes the spray liquid, increasing the contact area with ammonia and improving mass transfer efficiency. The nitrile production method includes the steps of subjecting a hydrocarbon raw material to an ammoxidation reaction to produce a reaction product containing nitrile, and cooling the reaction product by spraying the spray liquid onto the reaction product via a spraying apparatus, wherein the spraying apparatus comprises a spray liquid inlet, a first spray pipe fluid-communicating with the spray liquid inlet, a plurality of second spray pipes fluid-communicating with the first spray pipe and extending perpendicularly to both sides of the first spray pipe, a plurality of third spray pipes fluid-communicating with the second spray pipe and extending perpendicularly to both sides of the second spray pipe, and a nozzle located at the end of the third spray pipe and fluid-communicating with it. In the cooling step, the spray liquid input pressure at the spray liquid inlet is controlled to 0.06 to 1.00 MPaG.

Description

Technical Field

[0001] The present invention relates to the technical field of gas absorption, and more specifically, to a method and apparatus for nitrile production with a controlled spray liquid input pressure.

Background Art

[0002] In the production process of the corresponding nitrile by ammoniation or ammoxidation, in order to maximize the conversion rate of the raw material gas such as hydrocarbon, ammonia is used in an excessive amount with respect to the raw material gas, that is, the molar ratio of ammonia to the hydrocarbon raw material gas is greater than 1. Generally, for example, in the ammoxidation of propylene, the ammonia ratio (molar ratio of ammonia to propylene) is 1.10 to 1.35, and in the ammoxidation of aromatic hydrocarbons, the ammonia ratio (molar ratio of ammonia to aromatic hydrocarbons) is 4 to 8. Therefore, the tail gas at the reactor outlet always contains unreacted ammonia. On the other hand, in the acrylonitrile production process, etc., reaction gases such as acrylonitrile are likely to polymerize under alkaline conditions. On the other hand, even if a small amount of unreacted ammonia leaks out, it easily causes environmental pollution. Therefore, in the ammoniation or ammoxidation process, it is desirable to remove unreacted ammonia from the gas phase using an absorber (generally called an ammonia absorption column or a quench column) with an acid or water, and this process is very necessary.

[0003] With the development of production technology, the production load has been continuously increasing, and the trend of equipment enlargement indicates the future development direction. The higher the equipment load, the larger the equipment including the absorber. In the absorber, it is known that the circulating liquid (spray liquid) is distributed into the absorber through a spraying device and contacts the ammonia-containing gas to be absorbed in countercurrent to achieve the purpose of removing residual ammonia from the gas phase.

[0004] CN105425849 teaches that residual ammonia can be removed by adjusting the amount of acid added based on the pH value of the effluent from the absorber. CN1199940 teaches that mass transfer and heat transfer effects between gas and liquid can be improved by adding components to the bottom of the absorber. This effectively addresses the problem of uniform distribution of the ammonia-containing gas phase. However, the absorber is still unavoidable in that ammonia escape occurs, meaning that small amounts of ammonia escape still exist, causing product loss or environmental contamination in subsequent purification and separation equipment.

[0005] In conventional ammonia absorption methods, the ammonia content in the absorbed tail gas increases significantly when the absorption device is operated for a long period compared to the initial stage of operation. [Overview of the project]

[0006] The inventors of this invention discovered that because the circulating fluid contains a certain concentration of deposit-prone substances such as ammonium salts and polymers, after long operating cycles, these deposit-prone substances tend to adhere to the inner walls of the spray pipes and nozzles of the spraying device. This results in insufficient nozzle pressure in the spraying device, affecting the atomization effect. Furthermore, this deposit problem becomes more severe the further away from the spray liquid inlet. After long-term operation, the degree of deposit differs at different locations in the spraying device, and the degree of atomization of the spray liquid differs at different nozzles. In areas where atomization is insufficient, ammonia leakage becomes more pronounced. In existing devices, the problem of insufficient pressure is particularly pronounced at the nozzles furthest from the spraying device inlet. Ammonia absorption is not complete, and small amounts of ammonia still leak into subsequent equipment.

[0007] The inventors of this invention analyzed the degree of accumulation of easily deposited substances in various parts of the spraying device as the operating cycle continues and the effect of this on the atomization effect. As a result of comprehensively considering factors such as the non-uniformity of the accumulation rate throughout the spraying device and pressure loss along the piping route, they discovered that by setting the input pressure of the spray liquid at the spray liquid inlet of the spraying device to a specific value, the non-uniform accumulation phenomenon at various positions in the spraying device after long-term operation can be reduced or eliminated, and a uniform degree of atomization can be achieved overall.

[0008] The inventors of this invention have also discovered that in a single-stage ammonia absorption column, when an ammonia-containing gas is supplied into the column along a semicircular inlet pipe, and the gas is supplied from bottom to top, the gaseous ammonia is neutralized by the acid during countercurrent contact with the acidic circulating liquid. In existing devices, the distribution of ammonia in the gas phase is non-uniform in the cross-section where it contacts the first layer of the acidic circulating liquid within the column, resulting in a non-uniform ammonia distribution in cross-sections at each axial position as the gas rises. Typically, the acid concentration in the circulating liquid is increased to satisfy the ammonia absorption rate in regions with relatively high ammonia content. Therefore, the acid consumption in existing devices is relatively high.

[0009] The inventors of this invention have discovered that this problem can be solved by controlling the input pressure of the spray liquid at the spray liquid inlet to a specific numerical range, and more preferably by setting the vertical distance between the gas inlet and the spray liquid inlet to a specific numerical range. This invention was completed based on this discovery.

[0010] Specifically, the present invention relates to the following points.

[0011] 1. A method for producing nitrile, comprising the steps of: subjecting a hydrocarbon raw material to an ammoxidation reaction to produce a reaction product containing nitrile (referred to as the reaction step); and spraying a spray liquid onto the reaction product via a spraying device to cool the reaction product (referred to as the cooling step), wherein the spraying device comprises: a spray liquid inlet; a first spray pipe communicating with the spray liquid inlet; and a plurality of (for example, 10 to 26, preferably 12 to 2) pipes communicating with the first spray pipe and extending perpendicularly to both sides relative to the first spray pipe. A production method comprising two second spray pipes, a plurality (e.g., 4 to 26, preferably 6 to 22) third spray pipes that are in fluid communication with the second spray pipes and extend perpendicularly to both sides relative to the second spray pipes, and nozzles positioned at the ends of the third spray pipes and in fluid communication, wherein in the cooling process, the input pressure of the spray liquid at the spray liquid inlet is controlled to 0.06 to 1.00 MPaG (preferably 0.12 to 0.90 MPaG, more preferably 0.18 to 0.80 MPaG).

[0012] 2. A production method according to either the preceding or following embodiment, wherein a plurality of second spray pipes extend perpendicularly to the first spray pipe and substantially parallel to it horizontally toward the opposite side, and / or a plurality of third spray pipes extend perpendicularly to the second spray pipe and substantially parallel to it horizontally toward the opposite side.

[0013] 3. A production method according to either the above or below description, wherein the first spray pipe has an inner diameter of 160 to 480 mm (preferably 200 to 450 mm) and a length of 4500 to 11500 mm (preferably 4800 to 10500 mm), and / or, a plurality of second spray pipes are identical or different from each other, each independently having an inner diameter of 30 to 150 mm (preferably 40 to 120 mm) and each independently having a length of 1200 to 5750 mm (preferably 1800 to 5250 mm), and / or, a plurality of third spray pipes are identical or different from each other, each independently having an inner diameter of 10 to 60 mm (preferably 15 to 50 mm) and each independently having a length of 160 to 325 mm (preferably 175 to 300 mm).

[0014] 4. A production method according to either the preceding or following description, wherein the nozzles are identical or different from each other, and each nozzle independently has an inner diameter of 3 to 20 mm (preferably 6 to 14 mm) (see nozzle outlet), a rotating chamber diameter of 10.0 to 55.0 mm (preferably 13.0 to 45.0 mm), and a spray angle of 65 to 120° (preferably 70 to 100°).

[0015] 5. A production method according to either the above or below description, wherein on a first spray pipe, the horizontal spacing between two adjacent second spray pipes is 640 to 1300 mm (preferably 700 to 1200 mm), and / or, on the same second spray pipe, the horizontal spacing between two adjacent third spray pipes is 320 to 650 mm (preferably 350 to 600 mm), and / or, on two adjacent second spray pipes, the straight-line distance M between any end of a third spray pipe on one second spray pipe and any end of a third spray pipe on the other adjacent second spray pipe is 320 mm or more (preferably 350 mm or more).

[0016] 6. A production method according to either the above or below description, wherein the nozzles are identical or different from each other, and each nozzle independently has a spray liquid discharge rate of 0.5 to 7.5 t / h (preferably 0.9 to 6.5 t / h), and / or the nozzles may be identical or different from each other, and each nozzle independently has a spray liquid discharge pressure of 0.03 to 0.85 MPaG (preferably 0.04 to 0.65 MPaG) at the nozzle outlet.

[0017] 7. A production method according to either of the above or below descriptions, wherein in the cooling step, the spray liquid and the reaction product come into contact in a countercurrent manner.

[0018] 8. A production method according to either the above or below description, wherein the flow rate ratio of the spray liquid to the reaction product is 15 to 25:1 during the cooling process.

[0019] 9. A production method according to either the above or the following description, wherein the cooling step is carried out within an absorption device, and a plurality of (e.g., 2 to 10, preferably 4 to 8) spraying devices are arranged in layers within the absorption device at predetermined vertical intervals along the central axis of the absorption device.

[0020] 10. A production method according to either the preceding or following embodiment, wherein when an absorption device is cut in a direction perpendicular to its central axis to obtain a cross-section, at least one (preferably all) selected from the first spray tube, second spray tube, and third spray tube on one of the plurality of spray devices and at least one (preferably all) selected from the first spray tube, second spray tube, and third spray tube on another of the plurality of spray devices substantially coincide in projection in the cross-section.

[0021] 11. A production method according to either the preceding or following embodiment, characterized in that all nozzles of one spraying device and all nozzles of the other spraying device substantially coincide in cross-sectional projection, and / or two nozzles whose projections substantially coincide have the same spray diameter.

[0022] 12. A production method according to either the preceding or following embodiment, wherein the vertical distance between two adjacent spraying devices (calculated as the vertical distance between the spray liquid inlets of the spraying devices) is 650 to 1350 mm (preferably 750 to 1200 mm).

[0023] 13. A production method according to either of the above or below descriptions, wherein the difference (absolute value) of the spray liquid input pressure at the spray liquid inlet of any two spray devices is less than 0.024 MPa (preferably less than 0.018 MPa, more preferably less than 0.012 MPa).

[0024] 14. A production method according to either the above or below description, wherein the absorption device has an inner diameter of 4.5 to 11.5 m (preferably 4.8 to 10.5 m).

[0025] 15. The absorption device further comprises an outer shell and a gas inlet. The reaction product is supplied to the absorption device through the gas inlet, and the gas inlet is located below the spraying device along the central axis direction of the absorption device. The production method according to any of the foregoing or following embodiments.

[0026] 16. The vertical distance between the gas inlet and the spraying liquid inlet of the spraying device (when there are multiple spraying devices, it refers to the spraying device closest to the gas inlet) is 800 - 6000 mm (preferably 1000 - 5000 mm), and / or the gas inlet has an inner diameter of 800 - 1900 mm (preferably 900 - 1700 mm), and / or the linear velocity of the gas in the outer shell is 0.6 - 1.5 m / s (preferably 0.7 - 1.3 m / s). The production method according to any of the foregoing or following embodiments.

[0027] 17. In the internal space of the absorption device between the gas inlet and the spraying device (when there are multiple spraying devices, it refers to the spraying device closest to the gas inlet), there are no mechanical components that may substantially affect the gas flow. The production method according to any of the foregoing or following embodiments.

[0028] 18. In the reaction step, the hydrocarbon raw material is propylene, and the molar ratio of propylene / ammonia / air (calculated as molecular oxygen) is 1:1.1 - 1.3:1.8 - 2.0. The reaction is at a temperature of 420 - 440 °C, a reaction pressure (gauge pressure) of 0.03 - 0.14 MPa, and a catalyst weight hourly space velocity of 0.06 - 0.15 h -1 or the hydrocarbon raw material is isobutylene, and the molar ratio of isobutylene / ammonia / air (calculated as molecular oxygen) is 1:1.3 - 1.6:2.2 - 2.8. The reaction is at a temperature of 395 - 420 °C, a reaction pressure (gauge pressure) of 0.03 - 0.14 MPa, and a catalyst weight hourly space velocity of 0.08 - 0.17 h -1 The production method according to any of the foregoing or following embodiments.

[0029] 19. A production method according to either of the above or below embodiments, wherein in the cooling step, the spray liquid cools the reaction product from 195 to 235°C to 81 to 86°C, and / or, in the cooling step, the spray liquid reduces the ammonia content of the reaction product to 150 ppm or less.

[0030] 20. A nitrile production apparatus comprising a reactor, an absorption apparatus, and a pressure control device, wherein the reactor is configured to produce a reaction product containing nitrile by subjecting a hydrocarbon raw material to an ammoxidation reaction, and the absorption apparatus is configured to cool the reaction product by spraying a spray liquid onto the reaction product through a plurality of spray devices located inside it, each spray device independently comprising a spray liquid inlet, a first spray pipe in fluid communication with the spray liquid inlet, and a plurality of (e.g., 1) pipes in fluid communication with the first spray pipe and extending perpendicularly to both sides relative to the first spray pipe A production apparatus comprising: 0 to 26 (preferably 12 to 22) second spray pipes; a plurality (e.g., 4 to 26, preferably 6 to 22) third spray pipes that are in fluid communication with the second spray pipes and extend perpendicularly to both sides relative to the second spray pipes; and nozzles positioned at the ends of the third spray pipes and in fluid communication with them, wherein a pressure control device is configured to control the spray liquid input pressure at the spray liquid inlet of each spray apparatus to 0.06 to 1.00 MPaG (preferably 0.12 to 0.90 MPaG, more preferably 0.18 to 0.80 MPaG).

[0031] 21. A production apparatus according to either the preceding or following embodiment, wherein the absorption device further comprises an outer shell and a gas inlet, the gas inlet being located below the spray device along the central axis of the absorption device, and the vertical distance between the gas inlet and the spray liquid inlet of the spray device (if there are multiple spray devices, this refers to the spray device closest to the gas inlet) is 800 to 6000 mm (preferably 1000 to 5000 mm). [Effects of the Invention]

[0032] According to the present invention, even after long-term operation (for example, continuous operation for 18 months or more), the ammonia content in the absorbed tail gas does not increase significantly compared to the initial stage of operation, and a good ammonia absorption effect can be maintained for a long period of time, thereby reducing ammonia escape.

[0033] According to the present invention, ammonia gas is uniformly distributed within the absorption column, which is advantageous for ammonia absorption.

[0034] According to the present invention, sufficient gas-liquid contact is achieved, the ammonia absorption effect is excellent, and the amount of acid used can be reduced. [Brief explanation of the drawing]

[0035] [Figure 1] This is a schematic front view of a conventional ammonia absorption column. [Figure 2] This is a schematic front view of a conventional ammonia absorption column. [Figure 3A] This is a schematic front view of the ammonia absorption column of the present invention. [Figure 3B] This is a schematic front view of the ammonia absorption column of the present invention. [Figure 4A] This is a schematic front view of the ammonia absorption column of the present invention. [Figure 4B] This is a schematic front view of the ammonia absorption column of the present invention. [Figure 5] This is a schematic top view of the spraying device of the present invention. [Figure 6A] This is a schematic top view of the spraying device of the present invention. [Figure 6B] This is a schematic top view of the spraying device of the present invention. [Modes for carrying out the invention]

[0036] Explanation of reference symbols: 1: Ammonia absorption column 2: Internal components of the demister of an ammonia absorption column 3: Internal components of the ammonia absorption column spraying device; 3a to 3f are the spraying device. 4: Internal components of the gas distributor in the ammonia absorption column 5: Internal components of the ammonia absorption column spraying device; 5a-5b are the spraying device. 6: Upper circulation pump 7: Lower circulation pump 8: Supply of ammonia-containing gas 9: Gas phase outlet of ammonia absorption column 10: Upper water supply 11: Lower wastewater discharge 12: Discharge of upper ammonium salt-containing solution 13: Lower circulating fluid 14: Upper circulating fluid 15: Acid-containing solution 16: Circulating fluid 17: Circulation pump 18: Spray device inlet 19: First spray pipe of the spraying device 20a, 20b: Second spray pipe of the spraying device 21: Third spray pipe of the spraying device 22: Atomizing nozzle of spraying device 23: Gas distributor P1, P2, P3, P4, P5, P6: Input pressure of the spray liquid in the spraying device.

[0037] Embodiments of the present invention will be described in detail below. However, the scope of protection of the present invention is not limited to these embodiments and is determined by the appended claims.

[0038] All publications, patent applications, patents, and other references mentioned herein are incorporated herein by reference in their entirety. Unless otherwise defined, all technical and scientific terms used herein are to be construed as having the same meaning as that generally understood by those skilled in the art. In the event of any conflict, the definitions herein shall prevail.

[0039] In this specification, when introducing materials, substances, processes, procedures, apparatus, components, etc., that begin with "well known to those skilled in the art," or when beginning with expressions such as "prior art," the subject matter is intended to include not only those that were conventionally used by those skilled in the art at the time of filing, but also those that are not currently in common use but will become known among those skilled in the art as suitable for similar purposes.

[0040] In this specification, the term “substantially” means a deviation not exceeding 20%, preferably a deviation not exceeding 10% or 5%.

[0041] All percentages, parts, ratios, etc., mentioned herein are based on weight, and pressures are gauge pressures unless explicitly stated.

[0042] In the present invention, two or more embodiments or aspects of the present invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure herein and are within the scope of the present invention.

[0043] All technical details not mentioned herein should be directly applied to relevant information well known to those skilled in the art.

[0044] One embodiment of the present invention involves a process for producing nitriles, particularly (meth)acrylonitrile.

[0045] According to one embodiment, the nitrile manufacturing process includes a step of subjecting hydrocarbon raw materials to an ammoxidation reaction to produce a reaction product containing nitrile (referred to as the reaction step), and a step of spraying a spray solution onto the reaction product via a spraying device to cool the reaction product (referred to as the cooling step).

[0046] According to one embodiment, the spraying device comprises a spray liquid inlet, a first spray pipe that is in fluid communication with the spray liquid inlet, a plurality of (e.g., 10 to 26, preferably 12 to 22) second spray pipes that are in fluid communication with the first spray pipe and extend perpendicularly to both sides of the first spray pipe, a plurality of (e.g., 4 to 26, preferably 6 to 22) third spray pipes that are in fluid communication with the second spray pipe and extend perpendicularly to both sides of the second spray pipe, and a nozzle disposed at the end of the third spray pipe and in fluid communication with it.

[0047] The means of connecting the various spray tubes and the third spray tube and nozzles, etc., are not particularly limited by the present invention, and conventional connecting means in the art of those skilled in the art can be used. For example, fixed connections or detachable connections can be used, preferably screw connections or other detachable connecting means, and are not particularly limited.

[0048] According to one embodiment, the spray liquid is water or an acidic aqueous solution. Preferably, the ammonia-containing gas is brought into contact in a countercurrent with the acidic aqueous solution flowing from bottom to top as the spray liquid, and the acidic H contained in the aqueous solution is released. + This neutralizes and removes ammonia. Here, an acidic aqueous solution refers to an aqueous solution of an acidic substance. Examples of acidic substances include inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, or organic acids such as acrylic acid and acetic acid, as well as acidic salts such as ammonium sulfate, and are not particularly limited.

[0049] According to the present invention, the atomized droplets of the spray liquid sprayed from the nozzle have a very small droplet size, typically only 50 to 5000 μm, thereby effectively achieving a gas absorption function, particularly an ammonia removal function.

[0050] According to one embodiment, during the cooling process, the spray liquid input pressure at the spray liquid inlet is controlled to 0.06 to 1.00 MPaG (preferably 0.12 to 0.90 MPaG, more preferably 0.18 to 0.80 MPaG). The inventors have discovered that the circulating liquid is supplied to the spray device from the spray device inlet, passes through the first spray pipe, the second spray pipe, and the third spray pipe, and is supplied into the absorption column from the nozzle at the end of the third spray pipe. As the pressure gradually decreases along the direction of fluid flow, and droplet size is inversely proportional to pressure, the droplet size continuously increases along the direction of circulating liquid flow. That is, the droplet size formed by spray nozzles located farther from the spray inlet in the direction of fluid flow is larger than the droplet size formed by spray nozzles located closer to the spray inlet in the direction of fluid flow. For this reason, the ammonia absorption efficiency decreases at the far end from the spray inlet in the direction of fluid flow compared to the near end. Therefore, in order to ensure a sufficient atomization effect, it is essential to control the input pressure of the spray liquid at the spray inlet within the aforementioned range. Furthermore, if the device is operated for a long period of time, viscous polymers are produced during the reaction process, which mix with ammonium salts in the circulating liquid and adhere to the inner walls of the spray pipe and nozzle. This increases resistance along the piping path, and the rate of resistance increase becomes more pronounced, especially 18 months after the start of operation, causing a further decrease in pressure at the far-end nozzle. As a result, the droplet size at the far-end nozzle increases, and the atomization effect deteriorates. According to the present invention, by controlling the spray liquid input pressure at the spray liquid inlet within the above range, sufficient pressure can be ensured at the far-end nozzle even after long-term continuous operation, and the atomization effect can be guaranteed.

[0051] According to one embodiment, the multiple second spray tubes extend substantially parallel to the opposite side in a horizontal direction perpendicular to the first spray tube.

[0052] According to one embodiment, the multiple third spray tubes extend substantially parallel to the opposite side in a horizontal direction perpendicular to the second spray tube.

[0053] According to one embodiment, the first spray pipe has an inner diameter of 160 to 480 mm (preferably 200 to 450 mm) and a length of 4500 to 11500 mm (preferably 4800 to 10500 mm).

[0054] According to one embodiment, the multiple second spray pipes may be the same or different from each other, and each independently has an inner diameter of 30 to 150 mm (preferably 40 to 120 mm) and a length of 1200 to 5750 mm (preferably 1800 to 5250 mm).

[0055] According to one embodiment, the multiple third spray tubes may be identical or different from one another, and each independently has an inner diameter of 10 to 60 mm (preferably 15 to 50 mm) and a length of 160 to 325 mm (preferably 175 to 300 mm).

[0056] According to one embodiment, the nozzles may be identical or different from each other, and each nozzle independently has an inner diameter (referring to the nozzle outlet) of 3 to 20 mm (preferably 6 to 14 mm), a rotating chamber diameter of 10.0 to 55.0 mm (preferably 13.0 to 45.0 mm), and a spray angle of 65 to 120° (preferably 70 to 100°). According to the present invention, the rotating chamber can employ any rotating chamber structure known in the art, and is not particularly limited, as long as it allows the spray liquid to be discharged from the nozzle outlet while rotating after passing through the rotating chamber.

[0057] According to one embodiment, the horizontal distance between two adjacent second spray pipes on the first spray pipe is 640 to 1300 mm (preferably 700 to 1200 mm).

[0058] According to one embodiment, the horizontal distance between two adjacent third spray pipes on the same second spray pipe is 320 to 650 mm (preferably 350 to 600 mm).

[0059] According to one embodiment, in two adjacent second spray tubes, the straight-line distance M (as shown in Figures 6A and 6B) between any end of a third spray tube on one second spray tube and any end of a third spray tube on another adjacent second spray tube is 320 mm or more, preferably 350 mm or more. The inventors of the present invention have found that in order to improve ammonia absorption efficiency, it is generally necessary that any position in the internal cross-section of the column be covered by at least two overlapping conical liquid surfaces formed around the nozzle, and that the same situation applies to the column wall. If the distance between the ends of the two spray tubes is too large, the limitations of the nozzle structure make it difficult to satisfy the requirement that any position on the column wall be covered by overlapping liquid surfaces sprayed from two or more nozzles, increasing the likelihood of ammonia leaking through "gaps". If the distance between the ends of the two spray tubes is too small, it is necessary to increase the amount of circulating liquid in the ammonia absorption column in order to ensure the atomization quality of the spray liquid. In other words, the energy consumption of the pump increases.

[0060] According to one embodiment, the nozzles may be identical or different from each other, and each independently has a spray liquid discharge rate of 0.5 to 7.5 t / h (preferably 0.9 to 6.5 t / h).

[0061] In a preferred embodiment, the nozzles may be identical or different, and the spray liquid discharge pressure at each nozzle outlet is 0.03 to 0.85 MPaG (preferably 0.04 to 0.65 MPaG). The inventors of the present invention have found that pressure is one of the main factors that causes liquid to droplet in a spray nozzle of an ammonia absorption column. Within a certain pressure range, droplet size increases as the pressure decreases. Generally, smaller spray droplets are considered to have better mass and heat transfer efficiency than larger spray droplets. If the spray liquid discharge pressure at the nozzle outlet is less than 0.03 MPaG, the atomization effect of the acidic circulating liquid after passing through the spraying device is insufficient, and the droplet size becomes large. In other words, contact with ammonia becomes insufficient. If the spray liquid discharge pressure at the nozzle outlet exceeds 0.85 MPaG, the atomization effect of the acidic circulating liquid after passing through the spraying device is good, but the droplet size is too small, so the liquid is easily entrained by the gas and discharged from the ammonia absorption column, and the ammonium salt dissolved in the liquid causes unnecessary problems in subsequent processes. In addition, if the device is operated for a long period of time, the viscous polymer produced during operation will adhere to the inside of the nozzle lumen, increasing nozzle resistance and reducing the pressure at the nozzle outlet. For example, after 18 months of continuous operation, dirt will adhere to the inside of the nozzle, changing the movement of the spray liquid inside the nozzle. In particular, atomization instability at the far end nozzle increases, and this instability becomes more pronounced as the operating time of the device increases. According to the present invention, by controlling the spray liquid discharge pressure at the nozzle outlet within the above range, atomization at the far end nozzle can be stabilized even after long-term continuous operation, and the atomization effect can be ensured.

[0062] According to one embodiment, in the cooling process, the spray liquid and the reaction product are brought into contact in a countercurrent manner.

[0063] According to one embodiment, in the cooling process, the flow rate ratio of the spray liquid to the reaction product is 15 to 25:1.

[0064] According to one embodiment, the cooling process is carried out in an absorption device (particularly an ammonia absorption column or a quenching column), and a plurality of (e.g., 2 to 10, preferably 4 to 8) spraying devices are arranged in layers inside the absorption device at predetermined vertical intervals along the central axis of the absorption device.

[0065] According to one embodiment, when the absorber is cut in a direction perpendicular to the central axis of the absorber to obtain a cross-section, at least one (preferably all) selected from the first spray tube, second spray tube, and third spray tube on one of the plurality of sprayers and at least one (preferably all) selected from the first spray tube, second spray tube, and third spray tube on another of the plurality of sprayers substantially coincide in the projection in the cross-section.

[0066] According to one embodiment, all the nozzles of one spraying device and the other spraying device substantially coincide in their cross-sectional projection.

[0067] According to one embodiment, two nozzles whose projections substantially coincide have the same spray diameter.

[0068] According to one embodiment, the vertical distance between two adjacent spray devices (calculated as the vertical distance between the spray liquid inlets of the spray devices) is 650 to 1350 mm (preferably 750 to 1200 mm). The inventors of the present invention have found that when the vertical distance between two adjacent spray devices is less than 650 mm, in an ammonia absorption column with the same number of spray devices, the contact time between the rising ammonia-containing gas and the descending circulating liquid becomes insufficient, causing some of the ammonia in the gas phase to pass directly through the hollow conical liquid surface formed by the circulating liquid, thus reducing the ammonia absorption efficiency. Increasing the number of spray devices ensures sufficient gas-liquid contact time and allows for complete absorption of ammonia in the gas phase, but this increases the total volume of circulating liquid and thus increases the energy consumption of the pump, which is clearly uneconomical. When the vertical distance between two adjacent spray devices exceeds 1350 mm, the column height increases if the number of spray devices remains the same, which not only increases the capital investment cost but also increases the difficulty of maintenance and repair.

[0069] According to one embodiment, the difference (absolute value) in the spray liquid input pressure at the spray liquid inlet of any two spray devices is less than 0.024 MPa (preferably less than 0.018 MPa, more preferably less than 0.012 MPa). The inventors of the present invention have found that the particle size of the spray liquid is closely related to the nozzle pressure. Both excessively high and excessively low pressure are detrimental to the operation of the device. Since the nozzle pressure originates from the spray liquid input pressure at the spray liquid inlet, theoretically it is desirable that the spray liquid input pressure at the spray liquid inlet be the same. However, in reality, since the multi-layer spray devices are arranged vertically, pressure loss occurs when the circulation pump supplies circulating liquid to the spray devices of each layer. Therefore, the pressure difference between the spray liquid inlets of any two spray devices should be kept as small as possible, so that all nozzles of the uppermost and lowermost spray devices can meet the optimal pressure conditions.

[0070] According to one embodiment, the absorption device has an inner diameter of 4.5 to 11.5 m (preferably 4.8 to 10.5 m).

[0071] According to one embodiment, the absorption device further comprises an outer shell and a gas inlet. According to the present invention, the spraying device is located inside the outer shell of the absorption device. Furthermore, the reaction product is supplied to the absorption device through the gas inlet.

[0072] According to one embodiment, the gas inlet is located below the spraying device along the central axis direction of the absorption device.

[0073] In one embodiment, the vertical distance between the gas inlet and the spray liquid inlet of the spraying device (if there are multiple spraying devices, this refers to the spraying device closest to the gas inlet) is 800 to 6000 mm (preferably 1000 to 5000 mm). The inventors of the present invention discovered that the gas is introduced into the column through a downwardly curved semicircular inlet tube and then supplied from bottom to top. Relatively, the gas concentration is highest in the inlet tube. As the gas rises, the difference in gas concentration causes the gas to diffuse to the periphery, and eventually the gas concentration on the column cross-section becomes uniform. If the vertical distance is less than 800 mm, the gas concentration does not diffuse sufficiently, resulting in an uneven concentration distribution. This can easily lead to localized insufficient ammonia absorption or excessive acid supply. On the other hand, if the vertical distance is too large, the tangential height of the ammonia absorption column becomes excessive, increasing capital investment. Meanwhile, as the spray liquid rotates and falls, the colliding droplets exhibit behaviors such as separation, coalescence, and fragmentation. Coalescence forms larger droplets, and fragmentation forms smaller droplets. The longer the spray distance of the droplets, the more likely they are to coalesce or break apart, which is also detrimental to ammonia absorption.

[0074] According to one embodiment, the gas inlet has an inner diameter of 800 to 1900 mm (preferably 900 to 1700 mm).

[0075] According to one embodiment, the linear velocity of the gas inside the outer shell is 0.6 to 1.5 m / s (preferably 0.7 to 1.3 m / s). The inventors of the present invention have discovered that the operating speed inside the outer shell affects the gas diffusion speed. The higher the operating speed inside the outer shell, the stronger the turbulent effect, which is advantageous for gas diffusion and therefore shortens the diffusion distance. When the velocity inside the outer shell is less than 0.6 m / s, the time required for the gas to diffuse uniformly is relatively long, meaning that the distance from the inlet to the first layer of the spraying device increases. However, when the linear velocity inside the outer shell exceeds 1.5 m / s, the spray droplets from the spraying device usually become mist with a particle size of 50 to 5000 μm, and these mist droplets are easily entrained by the gas. The higher the velocity inside the outer shell, the more severe the mist entrainment phenomenon becomes, and as a result, more mist droplets containing ammonium salts are carried out of the ammonia absorption column by the gas.

[0076] According to one embodiment, the internal space of the absorption device between the gas inlet and the spraying device (if multiple spraying devices exist, this refers to the spraying device closest to the gas inlet) is free from mechanical components that could substantially affect the gas flow, particularly baffles, trays, packing materials, and other mechanical components that obstruct the gas flow. The inventors of the present invention have found that while it is possible to add internal components to ensure uniform distribution of gaseous ammonia across the cross-section before contact with the first layer of spray liquid, any type of mechanical component increases the system pressure of the device, which ultimately reflects as an increase in reaction pressure and reduces the yield of the target product. Smaller droplets result in a larger contact area between the droplet and gaseous ammonia, improving the absorption effect. Conversely, larger droplets worsen the ammonia absorption effect. Typically, the ammonia absorption efficiency of the first-layer spraying device is relatively high. As mentioned above, droplet sizes are 50-5000 μm, and the ammonia absorption efficiency of the first-layer spraying device is 30-55% or higher. If the droplets are too large, the ammonia absorption efficiency of the first layer decreases significantly, affecting the overall absorption efficiency. However, gases are relatively diffusive. Even if the gaseous ammonia is not perfectly uniformly distributed at the spraying position of the first layer, it continues to diffuse during the upward process and is captured and absorbed by the spray liquid of the subsequent spraying layer. Therefore, the objective of rapid and uniform dispersion of gaseous ammonia can be achieved by adding components here, but the vertical distance from the first layer spraying device to the inlet is 800 to 6000 mm, preferably 1000 to 5000 mm. This not only satisfies the efficient reaction of the preceding reaction section and the ammonia absorption efficiency of the column, but is also more economical for the entire apparatus.

[0077] According to one embodiment, in the reaction process, the hydrocarbon raw material is propylene, the molar ratio of propylene / ammonia / air (calculated as molecular oxygen) is 1:1.1~1.3:1.8~2.0, the reaction temperature is 420~440°C, the reaction pressure (gauge pressure) is 0.03~0.14 MPa, and the catalyst gravimetric time-space velocity is 0.06~0.15 h. -1Alternatively, the hydrocarbon raw material is isobutylene, the molar ratio of isobutylene / ammonia / air (calculated as molecular oxygen) is 1:1.3~1.6:2.2~2.8, the reaction temperature is 395~420°C, the reaction pressure (gauge pressure) is 0.03~0.14 MPa, and the catalyst weight-time-space velocity is 0.08~0.17 h. -1 That is the case.

[0078] According to one embodiment, depending on the various reaction steps, the composition of the reaction product is approximately 10-20% by weight of C, with the total weight of the reaction product being 100% by weight. 1-4 Nitrile (e.g., acrylonitrile), approximately 0.1-5% by weight of C 1-4 The reaction product contains oxygen-containing compounds (e.g., acrolein), approximately 0.1 to 5% by weight of O2, approximately 0.1 to 2% by weight of ammonia, and the remaining impurities. After pre-cooling, the temperature of the reaction product is approximately 195 to 235°C and the pressure is approximately 0.03 to 0.14 MPaG. According to the present invention, the technical effects of the manufacturing process described above are particularly excellent for this specific reaction product.

[0079] According to one embodiment, in the cooling step, the spray liquid cools the reaction product from 195-235°C to 81-86°C. More preferably, the spray liquid reduces the ammonia content of the reaction product to 150 ppm or less.

[0080] According to one embodiment, an apparatus for manufacturing nitrile is also provided. According to the present invention, the apparatus for manufacturing nitrile is specifically provided for carrying out the nitrile manufacturing process described above. Therefore, for matters not described in detail in the description of the apparatus, one can refer directly to the relevant matters described above regarding the manufacturing process.

[0081] According to one embodiment, the apparatus for producing nitriles comprises a reactor, an absorption apparatus, and a pressure control device. The reactor is configured to produce a reaction product containing nitrile by subjecting hydrocarbon raw materials to an ammoxidation reaction. The absorption apparatus is configured to cool the reaction product by spraying a spray liquid onto it through a plurality of spray devices located inside it. Each spray device independently comprises a spray liquid inlet, a first spray pipe that is in fluid communication with the spray liquid inlet, a plurality of second spray pipes that are in fluid communication with the first spray pipe and extend perpendicularly to both sides of the first spray pipe, a plurality of third spray pipes that are in fluid communication with the second spray pipe and extend perpendicularly to both sides of the second spray pipe, and a nozzle located at the end of the third spray pipe and in fluid communication with it. The pressure control device is configured to control the spray liquid input pressure at the spray liquid inlet of each spray device to 0.06 to 1.00 MPaG (preferably 0.12 to 0.90 MPaG, more preferably 0.18 to 0.80 MPaG).

[0082] According to one embodiment, the absorption device further comprises an outer shell and a gas inlet. According to the present invention, the spray device is located inside the outer shell. Furthermore, the reaction product is supplied to the absorption device through the gas inlet.

[0083] According to one embodiment, the gas inlet is located below the spraying device along the central axis of the absorption device, and the vertical distance between the gas inlet and the spray liquid inlet of the spraying device (if there are multiple spraying devices, this refers to the spraying device closest to the gas inlet) is 800 to 6000 mm (preferably 1000 to 5000 mm).

[0084] Specific embodiments of the present invention will be described in detail illustratively with reference to the drawings.

[0085] For example, as shown in Figure 4A, according to the present invention, a reaction gas at 225°C and unreacted ammonia are supplied to the ammonia absorption column 1 through the ammonia-containing gas supply inlet 8. The circulating liquid is drawn from the bottom of the column and sent to multi-layer sprayers 3a to 3f by the circulation pump 17. The sprayers 3a to 3f are arranged sequentially vertically within the column, with sprayers 3a, 3c, and 3e located on the same side, and sprayers 3b, 3d, and 3f located on the opposite side from sprayers 3a, 3c, and 3e. The vertical distance between the ammonia-containing gas supply inlet 8 and sprayer 3f is 1800 mm. The spray liquid input pressures at the spray liquid inlets of sprayers 3a, 3c, and 3e are 0.327 MPaG, 0.330 MPaG, and 0.334 MPaG, respectively. Sulfuric acid is added from the acid-containing solution inlet 15 to the outlet piping of the circulation pump. The circulating fluid is supplied through the spraying device 3, introduced from the inlet 18 of the spraying device, and reaches the spray nozzle 22 via the first spray pipe 19, the second spray pipe 20a (20b), and the third spray pipe 21 along the fluid direction. The circulating fluid sprayed from the nozzle 22 forms an acid mist layer in the ammonia absorption column and absorbs gaseous ammonia flowing in from the gas supply inlet 8. The tail gas is discharged from the gas phase outlet 9 of the ammonia absorption column. The temperature of the top tail gas is 84°C. As shown in Figure 5, the protruding ends of the third spray pipes of the spraying devices 3a to 3f coincide on the cross-section of the column. [Examples]

[0086] The present invention will be described in more detail with reference to the following embodiments. However, the present invention is not limited to these embodiments.

[0087] Example 1 As shown in Figure 3b, the ammonia absorption column had a two-stage structure. The inner diameter of the absorption column was 7200 mm, and no gas distributor 23 was installed inside the column. The linear velocity of the reaction gas in the column was 1.1 m / s. The acid added to the circulating fluid was sulfuric acid. The circulating fluid containing the acid was supplied to the absorption column from four sprayers via an upper circulation pump. The fluid direction in the first spray tubes of sprayers 3a and 3c was opposite to that of 3b and 3d. The spray fluid input pressure at the spray fluid inlet of sprayers 3a(b) and 3c(d) was 0.440 MPaG and 0.446 MPaG, respectively. The spray fluid discharge pressure was 0.051 MPaG. The distance between two adjacent sprayers was 1200 mm. Each sprayer had 16 second spray tubes, and the second spray tubes were equipped with 11 to 18 third spray tubes. The first spray pipe of the spraying device had an inner diameter of 250 mm and a length of 7000 mm. The spacing between the second spray pipes of the spraying device was 820 mm, and the second spray pipe had an inner diameter of 100 mm and a length of 2100 to 3450 mm. The spacing between two adjacent spraying devices was 1200 mm. The spacing between the third spray pipes of the spraying device was 410 mm, and the inner diameter of the third spray pipe was 40 mm and its length was 205 mm. The spraying device had a total of 960 nozzles. The nozzle outlet diameter was 11.5 mm, the nozzle rotation chamber diameter was 40 mm, and the nozzle spray angle was 75°. The vertical distance from the gas supply inlet 8 to spraying device 3d was 4000 mm, and the inner diameter of the supply inlet was 1300 mm. The reaction product gas supplied from the supply inlet contained approximately 0.71% by weight of ammonia, 13.2% by weight of acrylonitrile, and remaining impurities such as O2, acrolein, and nitrogen, at a temperature of 225°C and a pressure of 0.06 MPaG. The spray liquid discharge rate per nozzle was 4.8 t / h, and the weight ratio of spray liquid to reaction product gas supplied from the gas inlet was 20. In the initial stages of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 41 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 52 ppm.

[0088] Example 2 As shown in Figure 4, the ammonia absorption column had a single-stage structure. The inner diameter of the absorption column was 7200 mm, and no gas distributor 23 was installed inside the column. The linear velocity of the reaction gas in the column was 1.1 m / s. The acid added to the circulating fluid was sulfuric acid. The circulating fluid containing the acid was supplied to the absorption column from six sprayers via a circulation pump. The fluid direction in the first spray tubes of sprayers 3a, 3c, and 3e was opposite to that of 3b, 3d, and 3f. The spray fluid input pressures at the spray fluid inlets of sprayers 3a(b), 3c(d), and 3e(f) were 0.425 MPaG, 0.430 MPaG, and 0.435 MPaG, respectively. The spray fluid discharge pressure was 0.055 MPaG, respectively. The vertical distance between two adjacent sprayers was 880 mm. Each sprayer had 14 second spray tubes, and each second spray tube was equipped with 6 to 14 third spray tubes. The first spray pipe of the spraying device had an inner diameter of 200 mm and a length of 7000 mm. The second spray pipes of the spraying device were spaced 1000 mm apart, with an inner diameter of 100 mm and a length of 1850 to 3450 mm. The third spray pipes of the spraying device were spaced 500 mm apart, with an inner diameter of 40 mm and a length of 250 mm. The protruding ends of the third spray pipes of the spraying device coincided, and as shown in Figure 6A, the distance between the ends of two adjacent third spray pipes was 500 mm. The total number of nozzles in the spraying device was 912. The nozzle outlet diameter of the spraying device was 11.7 mm, the nozzle rotation chamber diameter was 36 mm, and the spray angle was 80°. The vertical distance from the gas supply inlet 8 to the spraying device 3f was 1500 mm, and the inner diameter of the supply inlet was 1200 mm. The reaction product gas supplied from the supply inlet contained approximately 0.71% by weight of ammonia, 13.2% by weight of acrylonitrile, and remaining impurities such as O2, acrolein, and nitrogen, at a temperature of 225°C and a pressure of 0.06 MPaG. The spray liquid discharge rate per nozzle was 5.1 t / h, and the weight ratio of spray liquid to reaction product gas passing through the gas inlet was 20. In the initial stages of operation of the apparatus, the residual ammonia concentration in the tail gas at the reaction outlet was 27 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 34 ppm.

[0089] Example 3 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of spray devices 3a(b), 3c(d), and 3e(f) were set to 0.152 MPaG, 0.160 MPaG, and 0.168 MPaG, respectively, and the nozzle outlet diameter of the spray device was set to 11.9 mm. In the initial stages of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 72 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 98 ppm.

[0090] Example 4 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of spray devices 3a(b), 3c(d), and 3e(f) were set to 0.838 MPaG, 0.844 MPaG, and 0.85 MPaG, respectively, the spray liquid discharge pressure was set to 0.42 MPaG, and the nozzle outlet diameter of the spray device was set to 12.1 mm. At the initial stage of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 84 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 92 ppm.

[0091] Example 5 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of spray devices 3a(b), 3c(d), and 3e(f) were set to 0.950 MPaG, 0.954 MPaG, and 0.959 MPaG, respectively, the spray liquid discharge pressure was set to 0.42 MPaG, and the nozzle outlet diameter of the spray device was set to 11.1 mm. At the initial stage of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 105 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 116 ppm.

[0092] Example 6 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of spray devices 3a(b), 3c(d), and 3e(f) were set to 0.098 MPaG, 0.103 MPaG, and 0.108 MPaG, respectively, the spray liquid discharge pressure was set to 0.04 MPaG, and the nozzle outlet diameter of the spray device was set to 12.3 mm. At the beginning of the device's operation, the residual ammonia concentration in the tail gas at the reaction outlet was 132 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 181 ppm.

[0093] Example 7 Example 2 was repeated, except that the vertical distance between two adjacent spraying devices was 1200 mm, and the distance between the ends of the two adjacent third spraying pipes shown in Figure 6B was 707 mm. The nozzle outlet diameter of the spraying device was 11.8 mm, and the spray liquid discharge rate per nozzle was 5.8 t / h. In the initial stages of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 68 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 96 ppm.

[0094] Example 8 The same procedure as in Example 2 was repeated, except that the vertical distance between two adjacent spraying devices was 1200 mm, each spraying device was equipped with 18 second spraying pipes, each second spraying pipe was equipped with 7 to 20 third spraying pipes, the spacing between the second spraying pipes of the spraying devices was 670 mm, the inner diameter of the second spraying pipes was 80 mm, and the distance between the ends of adjacent third spraying pipes as shown in Figure 6A was 335 mm. The total number of nozzles in the spraying devices was 2000. The nozzle outlet diameter of the spraying devices was 11.3 mm, the nozzle rotation chamber diameter was 30 mm, and the spray angle was 65°. The spray liquid discharge rate per nozzle was 2.64 t / h. In the initial stage of device operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 86 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 105 ppm.

[0095] Example 9 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of spray devices 3a(b), 3c(d), and 3e(f) were set to 0.376 MPaG, 0.380 MPaG, and 0.385 MPaG, respectively, the spray liquid discharge pressures were set to 0.045 MPaG, the vertical distance between two adjacent spray devices was set to 550 mm, and the distance between the ends of two adjacent third spray pipes shown in Figure 6B was set to 707 mm. At the initial stage of device operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 120 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 162 ppm.

[0096] Example 10 The vertical distance between two adjacent spraying devices was 1200 mm, each spraying device was equipped with 24 second spray pipes, each second spray pipe was equipped with 9 to 24 third spray pipes, the spacing between the second spray pipes of the spraying devices was 580 mm, the inner diameter of the second spray pipes was 80 mm, and the distance between the ends of adjacent third spray pipes shown in Figure 6A was 290 mm. The same procedure as in Example 2 was repeated. The total number of nozzles in the spraying devices was 2640. The nozzle outlet diameter was 9.1 mm, the nozzle rotation chamber diameter was 30 mm, and the spray angle was 65°. The spray liquid discharge rate per nozzle was 2.0 t / h. In the initial stage of device operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 146 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 185 ppm.

[0097] Example 11 Example 2 was repeated, except that the spray liquid discharge rate per nozzle was set to 8.5 t / h and the weight ratio of the spray liquid to the reaction product gas supplied from the gas inlet was set to 32. After 1 month of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 85 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 99 ppm.

[0098] Example 12 Example 2 was repeated, except that the spray liquid discharge rate per nozzle was set to 1.5 t / h and the weight ratio of the spray liquid to the reaction product gas supplied from the gas inlet was set to 11. After 1 month of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 145 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 178 ppm.

[0099] Example 13 Example 2 was repeated, except that the inlets of the sprayers 3a to 3f were positioned in different directions within the apparatus. Here, the first spray tubes of sprayers 3a to 3f coincided in cross-sectional projection, but the second spray tube, third spray tube, and nozzles did not coincide in cross-sectional projection. After one month of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 137 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 148 ppm.

[0100] Example 14 Example 2 was repeated, except that the nozzle diameters of the 1st to 11th second spray pipes of the first spray pipe were set to 36 mm along the fluid direction, and the nozzle diameters of the 12th to 14th second spray pipes of the first spray pipe were set to 32 mm. After 1 month of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 63 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 99 ppm.

[0101] Example 15 Example 2 was repeated, except that the vertical distance between two adjacent spraying devices was set to 1250 mm. In the initial stages of device operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 77 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 85 ppm.

[0102] Example 16 Example 2 was repeated, except that the vertical distance between two adjacent spraying devices was set to 720 mm. In the initial stages of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 111 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 129 ppm.

[0103] Example 17 Example 2 was repeated, except that the vertical distance between two adjacent spraying devices was set to 1650 mm. In the initial stages of device operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 177 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 195 ppm.

[0104] Example 18 Example 2 was repeated, except that the spray liquid input pressure at the spray liquid inlets of sprayers 3a(b), 3c(d), and 3e(f) was set to 0.405 MPaG, 0.421 MPaG, and 0.435 MPaG, respectively. In the initial stages of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 65 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 89 ppm.

[0105] Example 19 Example 2 was repeated, except that the spray liquid input pressure at the spray liquid inlets of sprayers 3a(b), 3c(d), and 3e(f) was set to 0.327 MPaG, 0.352 MPaG, and 0.376 MPaG, respectively. In the initial stages of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 112 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 145 ppm.

[0106] Example 20 Example 1 was repeated, except that the vertical distance from the gas inlet to the spraying device 3f was set to 6000 mm. At the beginning of the device's operation, the residual ammonia concentration in the tail gas at the reaction outlet was 77 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 85 ppm.

[0107] Example 21 Example 2 was repeated, except that the vertical distance from the gas inlet to the spraying device 3f was set to 8000 mm. In the initial stages of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 90 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 106 ppm. However, the increase in the total height of the column apparatus led to increased capital investment costs and also increased the difficulty of maintaining the apparatus.

[0108] Example 22 Example 2 was repeated, except that the vertical distance from the gas inlet to the spraying device 3f was set to 900 mm. In the initial stages of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 125 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 142 ppm.

[0109] Example 23 Example 2 was repeated, except that the vertical distance from the gas inlet to the spraying device 3f was set to 500 mm. In the initial stages of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 182 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 219 ppm.

[0110] Example 24 Example 2 was repeated, except that the gas partition 23 was placed inside the column, as shown in Figure 4B. The residual ammonia concentration in the tail gas at the reaction outlet was 35 ppm. After adding the internal components of the gas partition, the pressure at the bottom of the ammonia absorption column increased by 10 kPa. This increased the reaction pressure of the system preceding the ammonia absorption column by 10 kPa, resulting in a 1.5% decrease in the yield of the target product, nitrile.

[0111] Example 25 Example 2 was repeated, except that the linear velocity of the reaction gas in the column was set to 0.6 m / s and the spray liquid discharge rate per nozzle was set to 2.8 t / h. In the initial stages of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 82 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 99 ppm.

[0112] Example 26 Example 2 was repeated, except that the linear velocity of the reaction gas in the column was set to 1.4 m / s, the spray liquid discharge rate per nozzle was set to 5.1 t / h, and the weight ratio of the spray liquid to the reaction product gas supplied from the gas inlet was 17. In the initial stages of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 132 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 154 ppm.

[0113] Example 27 Example 2 was repeated, except that the linear velocity of the reaction gas in the column was set to 0.4 m / s and the spray liquid discharge rate per nozzle was set to 2.0 t / h. At the beginning of the apparatus operation, the residual ammonia concentration in the tail gas at the reaction outlet was 173 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 195 ppm.

[0114] Example 28 Example 2 was repeated, except that the linear velocity of the reaction gas in the column was set to 1.9 m / s, the spray liquid discharge rate per nozzle was set to 6.2 t / h, and the weight ratio of the spray liquid to the reaction product gas supplied from the gas inlet was 15. At the initial stage of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 182 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 199 ppm.

[0115] Example 29 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of spray devices 3a(b), 3c(d), and 3e(f) were set to 0.212 MPaG, 0.220 MPaG, and 0.228 MPaG, respectively, the spray liquid discharge pressure was set to 0.04 MPaG, and the nozzle outlet diameter of the spray device was 11.9 mm. At the initial stage of device operation, the residual ammonia concentration in the tail gas at the reaction outlet was 60 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 81 ppm.

[0116] Example 30 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of spray devices 3a(b), 3c(d), and 3e(f) were set to 0.780 MPaG, 0.784 MPaG, and 0.789 MPaG, respectively, and the spray liquid discharge pressure was set to 0.42 MPaG. At the initial stage of device operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 65 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 96 ppm.

[0117] Example 31 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of sprayers 3a(b), 3c(d), and 3e(f) were set to 0.185 MPaG, 0.190 MPaG, and 0.195 MPaG, respectively, and the vertical distance from the gas inlet to sprayer 3f was set to 1000 mm. At the beginning of the operation of the apparatus, the residual ammonia concentration in the tail gas at the reaction outlet was 85 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 112 ppm.

[0118] Example 32 Example 2 was repeated, except that the spray liquid input pressures at the spray liquid inlets of sprayers 3a(b), 3c(d), and 3e(f) were set to 0.79 MPaG, 0.795 MPaG, and 0.801 MPaG, respectively, and the vertical distance from the gas inlet to sprayer 3f was set to 4800 mm. At the beginning of the operation of the apparatus, the residual ammonia concentration in the tail gas at the reaction outlet was 91 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 116 ppm.

[0119] Comparative Example 1 The procedure was repeated from Example 1, except that the ammonia absorption column had a two-stage structure as shown in Figure 1. The spray liquid input pressures at the spray liquid inlets of sprayers 3a, 3b, 3c, and 3d were 0.04 MPaG, 0.044 MPaG, 0.046 MPaG, and 0.051 MPaG, respectively. The spray liquid discharge pressure was 0.02 MPaG, and the nozzle outlet diameter was 14.2 mm. In the initial stages of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 400 ppm. After 24 months of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 529 ppm.

[0120] Comparative Example 2 Example 2 was repeated, except that the ammonia absorption column was a single-stage structure as shown in Figure 2. The spray liquid input pressures at the spray liquid inlets of sprayers 3a, 3b, 3c, 3d, 3e, and 3f were 1.202 MPaG, 1.205 MPaG, 1.209 MPaG, 1.214 MPaG, 1.217 MPaG, and 1.220 MPaG, respectively. The spray liquid discharge pressure was 0.076 MPaG. In the initial stages of operation, the residual ammonia concentration in the exhaust gas at the reaction outlet was 85 ppm. After 24 months of operation, the residual ammonia concentration in the tail gas at the reaction outlet was 96 ppm. However, 1.5% ammonium sulfate was detected in the condensate of the tail gas from the ammonia absorption column outlet.

Claims

1. A method for producing nitrile, comprising the steps of: subjecting a hydrocarbon raw material to an ammoxidation reaction to produce a reaction product containing the nitrile (referred to as a reaction step); and spraying a spray liquid onto the reaction product via a spraying device to cool the reaction product (referred to as a cooling step), wherein the spraying device comprises a spray liquid inlet, a first spray pipe in fluid communication with the spray liquid inlet, a plurality of second spray pipes in fluid communication with the first spray pipe and extending perpendicularly to both sides relative to the first spray pipe, a plurality of third spray pipes in fluid communication with the second spray pipes and extending perpendicularly to both sides relative to the second spray pipe, and a nozzle disposed at the end of the third spray pipe and in fluid communication, wherein in the cooling step, the input pressure of the spray liquid at the spray liquid inlet is controlled to 0.06 to 1.00 MPaG (preferably 0.12 to 0.90 MPaG, more preferably 0.18 to 0.80 MPaG).

2. The production method according to claim 1, wherein in two adjacent second spray pipes, the straight-line distance M between any end of a third spray pipe on one second spray pipe and any end of a third spray pipe on the other adjacent second spray pipe is 320 mm or more (preferably 350 mm or more), and / or the nozzles are identical or different and each independently has a spray liquid discharge rate of 0.5 to 7.5 t / h (preferably 0.9 to 6.5 t / h), and / or the nozzles are identical or different and each independently has a spray liquid discharge pressure of 0.03 to 0.85 MPaG (preferably 0.04 to 0.65 MPaG) at the nozzle outlet, and / or in the cooling step, the flow rate ratio of the spray liquid to the reaction product is 15 to 25:

1.

3. The production method according to claim 1, wherein the cooling step is carried out within an absorption device, and a plurality of (for example, 2 to 10, preferably 4 to 8) of the spraying devices are arranged in layers within the absorption device at predetermined vertical intervals along the central axis direction of the absorption device.

4. The production method according to claim 3, wherein in a cross-section obtained by cutting the absorption device in a direction perpendicular to its central axis, at least one (preferably all) selected from the first spray pipe, second spray pipe, and third spray pipe on one of the plurality of spray devices and at least one (preferably all) selected from the first spray pipe, second spray pipe, and third spray pipe on another of the plurality of spray devices substantially coincide in projection in said cross-section.

5. The production method according to claim 4, wherein all nozzles of one spraying device and all nozzles of the other spraying device substantially coincide in cross-sectional projection, and / or two nozzles whose projections substantially coincide have the same spray diameter.

6. The production method according to claim 3, wherein the vertical distance between two adjacent spraying devices (calculated as the vertical distance between the spray liquid inlets of the two spraying devices) is 650 to 1350 mm (preferably 750 to 1200 mm).

7. The production method according to claim 3, wherein the difference (absolute value) of the spray liquid input pressure at the spray liquid inlet of any two spray devices is less than 0.024 MPa (preferably less than 0.018 MPa, more preferably less than 0.012 MPa).

8. The production method according to claim 3, wherein the absorption device further comprises an outer shell and a gas inlet, the reaction product is supplied to the absorption device through the gas inlet, and the gas inlet is located below the spraying device along the central axis direction of the absorption device.

9. The production method according to claim 8, wherein the vertical distance between the gas inlet and the spray liquid inlet of the spraying device (if there are multiple spraying devices, this refers to the spraying device closest to the gas inlet) is 800 to 6000 mm (preferably 1000 to 5000 mm), and / or the inner diameter of the gas inlet is 800 to 1900 mm (preferably 900 to 1700 mm), and / or the linear velocity of the gas in the outer shell is 0.6 to 1.5 m / s (preferably 0.7 to 1.3 m / s).

10. The production method according to claim 8, wherein no mechanical components that could substantially affect the gas flow are located in the internal space of the absorption device between the gas inlet and the spraying device (if there are multiple spraying devices, this refers to the spraying device closest to the gas inlet).

11. An apparatus for producing nitriles, comprising a reactor, an absorption device, and a pressure control device, wherein the reactor is configured to produce a reaction product containing nitrile by subjecting a hydrocarbon raw material to an ammoxidation reaction, the absorption device is configured to cool the reaction product by spraying a spray liquid onto the reaction product through a plurality of spray devices located inside it, each spray device independently comprising a spray liquid inlet, a first spray pipe in fluid communication with the spray liquid inlet, a plurality of second spray pipes in fluid communication with the first spray pipe and extending perpendicularly to both sides relative to the first spray pipe, a plurality of third spray pipes in fluid communication with the second spray pipe and extending perpendicularly to both sides relative to the second spray pipe, and a nozzle located at the end of the third spray pipe and in fluid communication with it, and the pressure control device is configured to control the spray liquid input pressure at the spray liquid inlet of each spray device to 0.06 to 1.00 MPaG (preferably 0.12 to 0.90 MPaG, more preferably 0.18 to 0.80 MPaG).

12. The absorbent device further comprises an outer shell and a gas inlet, the gas inlet being located below the spraying device along the central axis of the absorbent device, and the vertical distance between the gas inlet and the spray liquid inlet of the spraying device (if there are multiple spraying devices, this refers to the spraying device closest to the gas inlet) is 800 to 6000 mm (preferably 1000 to 5000 mm), according to claim 11.

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