Nitrile manufacturing method and manufacturing device with spraying liquid input pressure controlled

Abstract

The present invention relates to a method and an apparatus for producing nitrile with controlled spray liquid input pressure. According to the manufacturing method, spraying liquid can be atomized, the contact area with ammonia is increased, and the mass transfer efficiency is improved. The present invention relates to a method for producing nitrile, comprising a step (referred to as a reaction step) for producing a nitrile-containing reaction product by subjecting a hydrocarbon raw material to an ammoxidation reaction, and a step (referred to as a cooling step) for cooling the reaction product by spraying a spray liquid onto the reaction product by means of a spraying device, the spraying device comprises a spraying liquid inlet, a first spraying pipe in fluid communication with the spraying liquid inlet, and a plurality of second spraying pipes which are in fluid communication with the first spraying pipe, are perpendicular to the first spraying pipe and extend towards the two sides of the first spraying pipe. The first spraying pipe is communicated with the first spraying pipe through fluid, the second spraying pipe is communicated with the second spraying pipe through fluid, the third spraying pipes are communicated with the second spraying pipe through fluid and extend towards the two sides of the second spraying pipe perpendicular to the second spraying pipe, the nozzles are located at the tail ends of the third spraying pipes and communicated with the third spraying pipes through fluid, and in the cooling step, the spraying liquid input pressure of a spraying liquid inlet is controlled to be 0.06-1.00 MPaG.

Description

Technical Field

[0001] The present invention relates to the technical field of gas absorption, and more particularly to a method and a device for producing nitrile with controlled spray liquid input pressure. Background Art

[0002] In the process of generating corresponding nitriles by ammonia or ammoxidation, in order to convert the raw gas such as hydrocarbons as much as possible, the raw gas ammonia is generally excessive, that is, the molar ratio of ammonia to the raw gas hydrocarbon is greater than 1, such as in the ammoxidation of propylene, the ammonia ratio (ammonia to propylene molar ratio) is 1.10-1.35, and in the ammoxidation of aromatic hydrocarbons, the ammonia ratio (ammonia to aromatic hydrocarbon molar ratio) is 4-8, therefore, the reactor outlet tail gas must contain unreacted ammonia. On the one hand, such as in the acrylonitrile production process, acrylonitrile in the reaction gas is prone to polymerization under alkaline conditions, and on the other hand, even if a small amount of unreacted ammonia escapes, it is easy to cause environmental pollution. Therefore, in the ammonia or ammoxidation process, it is necessary to use an absorption device (generally referred to as an ammonia absorber or a quenching tower) to remove the unreacted ammonia in the gas phase with acid or water, and this process is very necessary.

[0003] With the development of production technology, production load is also increasing. Large-scale and large-scale equipment is the future development trend. The higher the load of the equipment, the larger the equipment including the absorption device. It is known that in the absorption device, the circulating liquid (spraying liquid) is spread in the absorption device through the spraying device, and is in reverse contact with the ammonia-containing gas to absorb, so as to remove the residual ammonia in the gas phase.

[0004] Patent CN105425849 removes the remaining ammonia by adjusting the amount of added acid according to the pH value of the effluent from the absorber; Patent CN1199940 improves the gas-liquid two-phase mass transfer and heat transfer effect by adding internal components at the bottom of the absorber, which is essentially to solve the problem of uniform distribution of the ammonia-containing gas phase. However, ammonia penetration will inevitably occur in the absorber, that is, a small amount of ammonia will still escape, resulting in product loss or environmental pollution in the subsequent refining and separation units.

[0005] Since the circulating fluid contains a certain concentration of ammonium salts and polymers, it is easy to adhere to the wall of the spray pipe and the inner wall of the nozzle, resulting in insufficient pressure at the nozzle at the end of the spray device, affecting the atomization effect, especially the nozzle farthest from the inlet of the spray device. In the existing device, ammonia absorption is not complete, and a small amount of ammonia still penetrates into the subsequent equipment. Summary of the invention

[0006] The inventors of the present invention have found that this problem can be solved by controlling the spray liquid input pressure of the spray liquid inlet within a specific value range. The present invention has been completed based on this finding.

[0007] In the first embodiment, the present invention relates to a method for producing nitrile, comprising a step of subjecting a hydrocarbon raw material to an ammoxidation reaction to produce a reaction product containing nitrile (referred to as a reaction step), and a step of spraying a spray liquid onto the reaction product through a spray device to cool the reaction product (referred to as a cooling step), wherein the spray device comprises a spray liquid inlet, a first spray pipe fluidly connected to the spray liquid inlet, a plurality of second spray pipes fluidly connected to the first spray pipe and extending perpendicularly to the first spray pipe to both sides thereof, a plurality of third spray pipes fluidly connected to the second spray pipe and extending perpendicularly to the second spray pipe to both sides thereof, and a nozzle located at the end of the third spray pipe and fluidly connected thereto, wherein in the cooling step, the spray liquid input pressure of the spray liquid inlet is controlled at 0.06-1.00MPaG.

[0008] In a second embodiment, the present invention relates to a nitrile manufacturing device, comprising a reactor, an absorption device and a pressure controller, wherein the reactor is constructed to cause a hydrocarbon feedstock to undergo an ammoxidation reaction to produce a reaction product containing nitrile, and the absorption device is constructed to spray a spray liquid onto the reaction product through a plurality of spray devices arranged therein to cool the reaction product, wherein each of the spray devices independently includes a spray liquid inlet, a first spray pipe fluidly connected to the spray liquid inlet, a plurality of second spray pipes fluidly connected to the first spray pipe and extending perpendicularly to the first spray pipe to both sides thereof, a plurality of third spray pipes fluidly connected to the second spray pipe and extending perpendicularly to the second spray pipe to both sides thereof, and a nozzle located at the end of the third spray pipe and fluidly connected thereto, and the pressure controller is constructed to control the spray liquid input pressure of the spray liquid inlet of each of the spray devices within a range of 0.06-1.00MPaG.

[0009] Technical Effects

[0010] According to the spraying device of the present invention, the gas-liquid contact is more complete and the ammonia absorption effect is better.

[0011] According to the spraying device of the present invention, the droplet particle size is more suitable for the operating conditions of the ammonia absorption tower.

[0012] The spraying device according to the present invention can maintain a good ammonia absorption effect for a long period (such as continuous operation for 18 months or even longer) and reduce the escape of ammonia. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a front view schematic diagram of an ammonia absorption tower in the prior art.

[0014] Figure 2 It is a front view schematic diagram of an ammonia absorption tower in the prior art.

[0015] Figure 3a , Figure 3b It is a front view schematic diagram of the ammonia absorption tower of the present invention.

[0016] Figure 4 It is a front view schematic diagram of the ammonia absorption tower of the present invention.

[0017] Figure 5 It is a schematic top view of a spraying device of the present invention.

[0018] Fig. 6A , Figure 6B It is a schematic top view of a spraying device of the present invention.

[0019] Description of reference numerals:

[0020] 1: Ammonia absorption tower

[0021] 2: Ammonia absorber internals demister

[0022] 3: Spraying device for internal components of ammonia absorption tower, 3a-3f are spraying devices

[0023] 4: Gas distributor for internal components of ammonia absorber

[0024] 5: Spraying device for internal components of ammonia absorption tower, 5a-5b is the spraying device

[0025] 6: Upper circulation pump

[0026] 7: Lower circulation pump

[0027] 8: Ammonia-containing gas feed

[0028] 9: Gas phase discharge from ammonia absorption tower

[0029] 10: Rehydration in the upper part

[0030] 11: Discharge of wastewater from the lower section

[0031] 12: Discharge of ammonium salt solution from the upper section

[0032] 13: Lower circulating fluid

[0033] 14: Upper circulating fluid

[0034] 15: Acid solution

[0035] 16: Circulating fluid

[0036] 17: Circulation pump

[0037] 18: Spraying device inlet

[0038] 19: Spraying device first spray pipe

[0039] 20a, 20b: Second spray pipe of the spraying device

[0040] 21: The third spray pipe of the spray device

[0041] 22: Spraying device atomizing nozzle

[0042] P1, P2, P3, P4, P5, P6: Inlet pressure of the spraying liquid of the spraying device DETAILED DESCRIPTION

[0043] The specific embodiments of the present invention are described in detail below, but it should be pointed out that the protection scope of the present invention is not limited by these specific embodiments, but is determined by the claims in the appendix.

[0044] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definitions in this specification shall prevail.

[0045] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0046] In the context of this specification, by substantially it is meant a deviation of no more than 20%, preferably no more than 10% or 5%.

[0047] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight and pressure is gauge pressure.

[0048] In the context of this specification, any two or more embodiments of the present invention may be arbitrarily combined, and the technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0049] In the context of this specification, all technical details etc. not mentioned are directly applicable to relevant information known in the art.

[0050] According to one embodiment of the present invention, it relates to a method for producing nitrile, in particular, a method for producing (meth)acrylonitrile.

[0051] According to one embodiment of the present invention, the method for producing nitrile includes a step of subjecting a hydrocarbon raw material to an ammoxidation reaction to produce a reaction product containing nitrile (referred to as a reaction step), and a step of spraying a spray liquid onto the reaction product by a spray device to cool the reaction product (referred to as a cooling step).

[0052] According to one embodiment of the present invention, the spray device includes a spray liquid inlet, a first spray pipe fluidically connected to the spray liquid inlet, a plurality of (e.g., 10-26, preferably 12-22) second spray pipes fluidically connected to the first spray pipe and extending perpendicularly to the first spray pipe on both sides thereof, a plurality of (e.g., 4-26, preferably 6-22) third spray pipes fluidically connected to the second spray pipe and extending perpendicularly to the second spray pipe on both sides thereof, and a nozzle located at the end of the third spray pipe and fluidically connected to it.

[0053] The present invention has no specific limitation on the connection method between the spray pipes and between the third spray pipe and the nozzle, and conventional connection methods in the art can be used. For example, fixed connection or detachable connection can be used, preferably threaded connection, or other detachable connection methods, which are not specifically limited.

[0054] According to one embodiment of the present invention, the spraying liquid is water or an acidic aqueous solution. Preferably, the ammonia-containing gas contacts the acidic aqueous solution as the spraying liquid from bottom to top in reverse from top to bottom, and the acidic H+ contained in the aqueous solution reacts with ammonia to remove the ammonia. Here, the acidic aqueous solution is an aqueous solution of an acidic substance. The acidic substance may be an inorganic acid, such as hydrochloric acid, sulfuric acid, phosphoric acid; may also be an organic acid, such as acrylic acid, acetic acid; may also be an acidic salt, such as ammonium sulfate, without specific limitation.

[0055] According to the present invention, the droplet size of the spray liquid sprayed from the nozzle is very small, usually only 50-5000 microns, which can effectively play the gas absorption function, especially the ammonia removal function.

[0056] According to one embodiment of the present invention, in the cooling step, the spray liquid input pressure of the spray liquid inlet is controlled at 0.06-1.00MPaG (preferably 0.12-0.90MPaG, more preferably 0.18-0.80MPaG). The inventor of the present invention found that the circulating liquid enters the spray device from the spray device inlet, passes through the first spray pipe, the second spray pipe, the third spray pipe, and is transported to the absorption tower through the nozzle at the end of the third spray pipe. Since the pressure gradually decreases along the direction of fluid travel, and the droplet particle size is inversely proportional to the pressure, the droplet particle size is continuously increased along the direction of circulation of the circulating liquid fluid, that is, the droplet size formed at the atomizing nozzle at the far end of the direction of fluid travel from the spray inlet is larger than the droplet size formed at the atomizing nozzle at the near end of the direction of fluid travel from the spray inlet, which also leads to the ammonia absorption efficiency at the far end of the direction of fluid travel from the spray inlet is lower than the ammonia absorption efficiency at the near end of the direction of fluid travel from the spray inlet. The spray liquid input pressure at the spray liquid inlet is controlled within the aforementioned specified range to meet the sufficient pressure of the remote nozzle and ensure the atomization effect. In addition, as the device runs for a long time, the polymer with a certain viscosity produced in the reaction process and the ammonium salt mixed in the circulating liquid adhere to the wall of the spray pipe, resulting in a continuous increase in the resistance of the pipe side. In particular, after the device has been running for 18 months, the increase in the resistance of the pipe side is more obvious, and the pressure of the remote nozzle is further reduced, resulting in a larger droplet size of the remote nozzle and a worse atomization effect. According to the present invention, by controlling the spray liquid input pressure at the spray liquid inlet within the aforementioned specified range, even after a long period of continuous operation, the remote nozzle can meet the sufficient pressure to ensure the atomization effect.

[0057] According to one embodiment of the present invention, the plurality of second spraying pipes extend substantially in parallel along a horizontal direction perpendicular to the first spraying pipe toward opposite sides thereof.

[0058] According to one embodiment of the present invention, the plurality of third spraying pipes extend substantially in parallel along a horizontal direction perpendicular to the second spraying pipe toward opposite sides thereof.

[0059] According to one embodiment of the present invention, the inner diameter of the first spray pipe is 160-480 mm (preferably 200-450 mm), and the length is 4500-11500 mm (preferably 4800-10500 mm).

[0060] According to one embodiment of the present invention, the plurality of second spray pipes are the same as or different from each other, and each has an inner diameter independently of 30-150 mm (preferably 40-120 mm) and a length independently of 1200-5750 mm (preferably 1800-5250 mm).

[0061] According to one embodiment of the present invention, the plurality of third spray pipes are the same as or different from each other, and each independently has an inner diameter of 10-60 mm (preferably 15-50 mm) and a length of 160-325 mm (preferably 175-300 mm).

[0062] According to one embodiment of the present invention, the nozzles are the same or different from each other, the inner diameter (referring to the nozzle outlet) is independently 3-20mm (preferably 6-14mm), the diameter of the rotating chamber is independently 10.0-55.0mm (preferably 13.0-45.0mm), and the spraying angle is independently 65-120° (preferably 70-100°). According to the present invention, the rotating chamber can adopt any structure known in the art, as long as the spray liquid can leave the nozzle outlet in a rotating manner after passing through the rotating chamber, and there is no special limitation.

[0063] According to one embodiment of the present invention, on the first spray pipe, the horizontal interval between two adjacent second spray pipes is 640-1300 mm (preferably 700-1200 mm).

[0064] According to one embodiment of the present invention, on the same second spraying pipe, the horizontal distance between two adjacent third spraying pipes is 320-650 mm (preferably 350-600 mm).

[0065] According to one embodiment of the present invention, on two adjacent second spray pipes, the straight-line distance M (e.g., Fig. 6A , Figure 6B The distance between the ends of the two spray pipes is not less than 320 mm, preferably not less than 350 mm. The inventors of the present invention have found that in order to improve the ammonia absorption efficiency, generally at any position on the cross section of the tower, there are at least two or more conical liquid surfaces formed with the nozzle as the center, including the tower wall. If the distance between the ends of the two spray pipes is too large, it is difficult to meet the overlap of the liquid surfaces sprayed by more than two nozzles at any position on the tower wall due to the limitation of the nozzle structure, which increases the probability of ammonia escaping from the "gap". If the distance between the ends of the two spray pipes is too small, in order to ensure the atomization quality of the spray liquid, the amount of circulating liquid in the ammonia absorption tower will inevitably increase, that is, the energy consumption of the pump will increase.

[0066] According to one embodiment of the present invention, the nozzles are the same as or different from each other, and the spraying liquid spraying amount is independently 0.5-7.5 t / h (preferably 0.9-6.5 t / h).

[0067] According to a preferred embodiment of the present invention, the nozzles are the same or different from each other, and the spraying pressure of the spraying liquid at the nozzle outlet is independently 0.03-0.85MPaG (preferably 0.04-0.65MPaG). The inventor of the present invention found that for the atomizing nozzle of the ammonia absorber, pressure is one of the main factors that promote the formation of droplets by the liquid. Within a certain pressure range, the size of the droplet particle size will increase as the pressure decreases. Compared with large atomized droplets, small atomized droplets are generally considered to have better mass transfer and heat transfer efficiency. When the spraying pressure of the spraying liquid at the nozzle outlet is less than 0.03MPaG, the atomization effect of the acidic circulating liquid after passing through the spraying device is poor, and the droplet particle size is large, that is, the contact with ammonia is not sufficient; when the spraying pressure of the spraying liquid at the nozzle outlet is greater than 0.85MPaG, although the atomization effect of the acidic circulating liquid after passing through the spraying device is good, due to the small droplet particle size, the liquid is easily entrained out of the ammonia absorber by the gas, and the ammonium salt dissolved in the liquid brings unnecessary trouble to the subsequent process. In addition, as the device runs for a long time, the viscous polymers produced during the operation of the device also adhere to the inner cavity of the nozzle, increasing the resistance of the nozzle and causing the pressure at the nozzle outlet to decrease. For example, after the device has been running continuously for 18 months, dirt adheres to the inner cavity of the nozzle, changing the movement of the spray liquid in the nozzle, and in particular, increasing the instability of the atomization of the distal nozzle. This instability will become more prominent as the device runs longer. According to the present invention, by controlling the spray pressure of the spray liquid at the nozzle outlet within the aforementioned specified range, even after a long period of continuous operation, the atomization of the distal nozzle can be ensured to be stable and the atomization effect can be guaranteed.

[0068] According to one embodiment of the present invention, in the cooling step, the spraying liquid contacts the reaction product in a countercurrent manner.

[0069] According to one embodiment of the present invention, in the cooling step, the flow ratio of the spraying liquid to the reaction product is 15-25:1.

[0070] According to one embodiment of the present invention, the cooling step is carried out in an absorption device (particularly an ammonia absorption tower or a quenching tower), and a plurality of (e.g., 2-10, preferably 4-8) of the spraying devices are layered inside the absorption device at a predetermined vertical spacing along the central axis direction of the absorption device.

[0071] According to one embodiment of the present invention, when the cross section is obtained by cross-cutting the absorption device in a direction perpendicular to the central axis of the absorption device, the projections of at least one (preferably all) of the first spray pipe, the second spray pipe and the third spray pipe selected from one of the multiple spray devices and another of the multiple spray devices on the cross section basically coincide.

[0072] According to one embodiment of the present invention, projections of all nozzles of the one spraying device and the other spraying device on the cross section substantially coincide with each other.

[0073] According to one embodiment of the present invention, two nozzles whose projections substantially coincide with each other have the same spray diameter.

[0074] According to one embodiment of the present invention, the vertical spacing between two adjacent spraying devices (measured by the vertical spacing of the spraying liquid inlet of the spraying device) is 650-1350mm (preferably 750-1200mm). The inventor of the present invention found that when the vertical spacing between two adjacent spraying devices is less than 650mm, for an ammonia absorption tower with the same number of spraying devices, due to the insufficient contact time between the rising ammonia-containing gas and the descending circulating liquid, part of the ammonia in the gas phase directly passes through the hollow conical liquid surface formed by the circulating liquid, resulting in poor ammonia absorption efficiency. Although sufficient gas-liquid contact time can be met by increasing the number of spraying devices to achieve complete absorption of ammonia in the gas phase, the total amount of circulating liquid will be increased, and the energy consumption of the pump will be increased, which is obviously uneconomical. When the vertical spacing between two adjacent spraying devices is greater than 1350mm, in the case of the same spraying device, the height of the tower will increase, that is, the equipment investment cost will increase, and in addition, the difficulty of maintenance and repair will be increased.

[0075] According to one embodiment of the present invention, the difference (absolute value) in the spray liquid input pressure of any two of the spray devices' spray liquid inlets is less than 0.024MPa (preferably less than 0.018MPa, more preferably less than 0.012MPa). The inventors of the present invention have found that the size of the droplets of the circulating liquid after atomization is closely related to the pressure of the nozzle. Too much or too little pressure is not conducive to the operation of the device. The nozzle pressure starts from the spray liquid input pressure of the spray liquid inlet. In theory, it is hoped that the spray liquid input pressures of the spray liquid inlets are the same. However, in reality, since the multi-layer spray devices are arranged up and down, there is a pressure drop loss when the circulating pump transports the circulating liquid to each layer of the spray devices. Therefore, the difference in the spray liquid input pressure of the spray liquid inlets of any two spray devices is as low as possible so that all nozzles of the top and bottom spray devices can meet the optimal pressure conditions.

[0076] According to one embodiment of the present invention, the inner diameter of the absorption device is 4.5-11.5 m (preferably 4.8-10.5 m).

[0077] According to one embodiment of the present invention, in the reaction step, the hydrocarbon feedstock is propylene, the molar ratio of propylene / ammonia / air (in terms of 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 weight hourly space velocity is 0.06-0.15 h -1Alternatively, the hydrocarbon feedstock is isobutylene, the molar ratio of isobutylene / ammonia / air (in terms of 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 hourly space velocity is 0.08-0.17 h -1 .

[0078] According to one embodiment of the present invention, in the cooling step, the spraying liquid cools the temperature of the reaction product from 425-445°C (or 390-420°C) to 81-86°C (or 87-95°C).

[0079] According to one embodiment of the present invention, in the cooling step, the spraying liquid reduces the ammonia content of the reaction product to below 150 ppm.

[0080] According to one embodiment of the present invention, it is also related to a manufacturing device of nitrile. According to the present invention, the manufacturing device of the nitrile is specifically used to implement the manufacturing method of the nitrile described above. For this reason, the content not described in detail in the manufacturing device part can directly refer to the related content described for the manufacturing method above.

[0081] According to one embodiment of the present invention, the nitrile manufacturing device includes a reactor, an absorption device and a pressure controller, wherein the reactor is configured to cause ammoxidation reaction of a hydrocarbon feedstock to produce a reaction product containing nitrile, and the absorption device is configured to spray a spray liquid to the reaction product through a plurality of spray devices arranged therein to cool the reaction product, wherein each of the spray devices independently includes a spray liquid inlet, a first spray pipe fluidly connected to the spray liquid inlet, a plurality of second spray pipes fluidly connected to the first spray pipe and extending perpendicularly to the first spray pipe to both sides thereof, a plurality of third spray pipes fluidly connected to the second spray pipe and extending perpendicularly to the second spray pipe to both sides thereof, and a nozzle located at the end of the third spray pipe and fluidly connected thereto, and the pressure controller is configured to control the spray liquid input pressure of the spray liquid inlet of each of the spray devices to be 0.06-1.00MPaG (preferably 0.12-0.90MPaG, more preferably 0.18-0.80MPaG).

[0082] A specific embodiment of the present invention is described in detail below by way of example with reference to the accompanying drawings.

[0083] like Figure 4As shown, according to the present invention, the reaction gas with a temperature of 440°C and unreacted ammonia enter the ammonia absorption tower 1 from the ammonia-containing gas feed port 8, and the circulating liquid is extracted from the bottom of the tower and sent to the spraying device 3a-spraying device 3f through the circulating pump 17, wherein the spraying devices 3a\3c\3e are on the same side, and the spraying devices 3b\3d\3f are on the opposite side to the spraying devices 3a\3c\3e. The spraying liquid input pressures of the spraying liquid inlets of the spraying devices 3a\3c\3e are 0.327MPaG, 0.330MPaG, and 0.334MpaG, respectively. The spraying devices 3a\3c\ The spray liquid input pressures at the spray liquid inlet 3e are 0.327MPaG, 0.330MPaG, and 0.334MpaG, respectively. Sulfuric acid is added to the circulating pump outlet pipeline from the acid solution port 15. The circulating liquid passes through the spray device 3 and enters from the inlet 18 of the spray device 3. It passes through the first spray pipe 19, the second spray pipe 20a (20b), and the third spray pipe 21 along the fluid direction to the atomizing nozzle 22. The circulating liquid is sprayed from the nozzle 22 to form an acid mist liquid layer in the ammonia absorption tower, which absorbs the gaseous ammonia from the gas feed port 8, and the tail gas is discharged from the ammonia absorption tower from the gas phase discharge port 9. The tail gas temperature at the top of the tower is 84°C. The projections of the ends of the third spray pipes of the spray devices 3a-3f overlap on the cross section of the tower, as shown in FIG. Figure 5 shown.

[0084] Example

[0085] The present invention is further described in detail below using examples, but the present invention is not limited to these examples.

[0086] Example 1

[0087] Ammonia absorption tower Figure 3bThe two-stage structure has an inner diameter of 7200mm. The acid added to the circulating liquid is sulfuric acid. The acid-containing circulating liquid is delivered to the absorption tower through the upper circulation pump through four spraying devices. The fluid directions in the first spraying pipes of spraying devices 3a, 3c and 3b, 3d are opposite. The spraying liquid input pressures at the spraying liquid inlets of spraying devices 3a(b) and 3c(d) are 0.440MPaG and 0.446MPaG respectively. The spraying liquid spraying pressure is 0.051MPaG. The interval between two adjacent spraying devices is 1200mm. Each spraying device has 16 second spraying pipes, and the second spraying pipes are provided with 11 to 18 third spraying pipes. The inner diameter of the first spray pipe of the spray device is 250mm, and the length of the first spray pipe is 7000mm; the spacing of the second spray pipe of the spray device is 820mm, the inner diameter of the second spray pipe is 100mm, and the length of the second spray pipe is 2100mm-3450mm; the spacing of the third spray pipe of the spray device is 410mm, the inner diameter of the third spray pipe is 40mm, and the length of the third spray pipe is 205mm; the spray device has a total of 960 nozzles, the nozzle outlet diameter is 11.5mm, the nozzle rotation chamber diameter is 40mm, the nozzle spray angle is 75°, the spray liquid spray volume of each nozzle is 4.8t / h, and the weight ratio of the spray liquid to the gas entering from the gas inlet is 20. At the beginning of the operation of the device, the residual ammonia concentration of the tail gas from the reaction outlet was 41ppm, and the residual ammonia concentration of the tail gas from the reaction outlet was 52ppm after the device was operated for 24 months. .

[0088] Example 2

[0089] Ammonia absorption tower Figure 4 The absorber has a one-stage structure, the inner diameter of the absorber is 7200 mm, the acid added to the circulating liquid is sulfuric acid, and the circulating liquid containing the acid is delivered to the absorber through 6 spraying devices via a circulating pump, wherein the fluid directions in the first spraying pipes of the spraying devices 3a, 3c, 3e and 3b, 3d, 3f are opposite, the spraying liquid input pressures at the spraying liquid inlets of the spraying devices 3a(b), 3c(d) and 3e(f) are 0.425 MPaG, 0.430 MPaG, 0.435 MPaG, respectively, and the spraying liquid spraying pressures are 0.055 MPaG, respectively, and the vertical spacing between two adjacent spraying devices is 880 mm, and each spraying device has 14 second spraying pipes, and the second spraying pipes are provided with 6 to 14 third spraying pipes. The inner diameter of the first spray pipe of the spray device is 200mm, and the length of the first spray pipe is 7000mm; the spacing of the second spray pipes of the spray device is 1000mm, the inner diameter of the second spray pipe is 100mm, and the length is 1850mm-3450mm; the spacing of the third spray pipes of the spray device is 500mm, the inner diameter of the third spray pipe is 40mm, and the length is 250mm. The projections of the third spray ends of the spray device overlap. If two adjacent third spray pipes are Fig. 6AThe end distance shown is 500mm; the spraying device has a total of 912 nozzles, the nozzle outlet diameter of the spraying device is 11.7mm, the nozzle rotation chamber diameter is 36mm, the spraying angle is 80°, the spraying liquid spraying amount of each nozzle is 5.1t / h, and the weight ratio of the spraying liquid to the gas entering from the gas inlet is 20. At the beginning of the operation of the device, the residual ammonia concentration of the tail gas from the reaction outlet was 27ppm, and the residual ammonia concentration of the tail gas from the reaction outlet was 34ppm after the device was operated for 24 months.

[0090] Example 3

[0091] The same as Example 2, the only difference is that the spray liquid input pressures at the spray liquid inlets of the spray devices 3a (b), 3c (d) and 3e (f) are 0.098 MPaG, 0.103 MPaG, and 0.108 MPaG, respectively, and the spray liquid spray pressures are 0.04 MPaG, respectively. The nozzle outlet diameter of the spray device is 12.3 mm. At the initial stage of the device operation, the residual ammonia concentration of the tail gas from the reaction outlet is 85 ppm. After the device has been in operation for 24 months, the residual ammonia concentration of the tail gas from the reaction outlet is 108 ppm.

[0092] Example 4

[0093] The same as Example 2, the only difference is that the spray liquid input pressures of the spray liquid inlets of the spray devices 3a (b), 3c (d) and 3e (f) are 0.900 MPaG, 0.904 MPaG, and 0.909 MPaG, respectively, and the spray liquid spray pressures are 0.42 MPaG, respectively. The nozzle outlet diameter of the spray device is 11.1 mm. At the initial stage of the device operation, the residual ammonia concentration of the tail gas from the reaction outlet is 65 ppm. After the device has been in operation for 24 months, the residual ammonia concentration of the tail gas from the reaction outlet is 92 ppm.

[0094] Example 5

[0095] The same as Example 2, except that the vertical spacing between two adjacent spraying devices is 1200 mm, each spraying device has 24 second spraying pipes, and the second spraying pipes are provided with 9 to 24 third spraying pipes. The spacing between the second spraying pipes of the spraying device is 580 mm, the inner diameter of the second spraying pipe is 80 mm, and the vertical spacing between two adjacent third spraying pipes is 1200 mm. Fig. 6A The end distance shown is 290mm. The spraying device has a total of 2640 nozzles, the nozzle outlet diameter of the spraying device is 9.1mm, the nozzle rotation chamber diameter is 30mm, the spraying angle is 65°, and the spraying liquid spraying amount of each nozzle is 2.0t / h. At the beginning of the operation of the device, the residual ammonia concentration of the tail gas from the reaction outlet was 106ppm. After 24 months of operation, the residual ammonia concentration of the tail gas from the reaction outlet was 115ppm.

[0096] Example 6

[0097] The same as Example 2, except that the spray liquid input pressures of the spray liquid inlets of the spray devices 3a (b), 3c (d) and 3e (f) are 0.376 MPaG, 0.380 MPaG and 0.385 MPaG respectively; the spray liquid spray pressures are 0.045 MPaG respectively, the vertical spacing between two adjacent spray devices is 550 mm, and the adjacent third spray pipes are as follows: Figure 6B The end distance shown is 707 mm. At the beginning of the operation of the device, the residual ammonia concentration of the tail gas from the reaction outlet was 120 ppm. After 24 months of operation, the residual ammonia concentration of the tail gas from the reaction outlet was 132 ppm.

[0098] Example 7

[0099] The same as Example 2, except that the vertical spacing between two adjacent spraying devices is 1200 mm, and the two adjacent third spraying pipes are as follows: Figure 6B The end distance shown is 707mm. The nozzle outlet diameter of the spraying device is 11.8mm, and the spraying liquid spraying amount of each nozzle is 5.8t / h. At the beginning of the operation of the device, the residual ammonia concentration of the tail gas from the reaction outlet is 98ppm. After the device has been in operation for 24 months, the residual ammonia concentration of the tail gas from the reaction outlet is 116ppm.

[0100] Example 8

[0101] The same as Example 2, the only difference is that the spray liquid input pressures at the spray liquid inlets of spray devices 3a (b), 3c (d) and 3e (f) are 0.405MPaG, 0.0421MpaG, and 0.435MpaG, respectively. At the initial stage of the device operation, the residual ammonia concentration of the tail gas from the reaction outlet is 65ppm. After the device has been in operation for 24 months, the residual ammonia concentration of the tail gas from the reaction outlet is 89ppm.

[0102] Example 9

[0103] The same as Example 2, the only difference is that the spray liquid input pressures at the spray liquid inlets of the spray devices 3a (b), 3c (d) and 3e (f) are 0.920 MPaG, 0.934 MPaG, and 0.959 MPaG, respectively, and the spray liquid discharge pressures are 0.88 MPaG, respectively. At the initial stage of the device operation, the residual ammonia concentration in the tail gas from the reaction outlet is 112 ppm. After the device has been in operation for 24 months, the residual ammonia concentration in the tail gas from the reaction outlet is 145 ppm.

[0104] Comparative Example 1

[0105] The same as Example 1, except that the ammonia absorption tower adopts Figure 1The two-stage structure has the following features: the spray liquid input pressures at the spray liquid inlets of the spray devices 3a, 3b, 3c and 3d are 0.04MPaG, 0.044MPaG, 0.046MPaG and 0.051MPaG respectively; the spray liquid discharge pressure is 0.02MPaG; the nozzle outlet diameter is 14.2mm; at the initial stage of the device operation, the residual ammonia concentration in the tail gas at the reaction outlet is 400ppm; after the device has been in operation for 24 months, the residual ammonia concentration in the tail gas at the reaction outlet is 529ppm.

[0106] Comparative Example 2

[0107] Same as Example 2, except that the ammonia absorption tower adopts Figure 2 The device has a one-stage structure, with spraying devices 3a, 3b, 3c, 3d, 3e and 3f. The spraying liquid input pressures at the spraying liquid inlet are 1.202MPaG, 1.205MPaG, 1.209MpaG, 1.214MPaG, 1.217MPaG and 1.220MpaG respectively. The spraying liquid discharge pressure is 0.076MPaG. At the initial stage of operation of the device, the residual ammonia concentration in the tail gas from the reaction outlet is 85ppm. After 24 months of operation of the device, the residual ammonia concentration in the tail gas from the reaction outlet is 96ppm. However, 1.5% ammonium sulfate is detected in the tail gas condensate at the outlet of the ammonia absorption tower.

Claims

1. A method for producing a nitrile, comprising the steps of making a hydrocarbon feedstock undergo ammoxidation reaction and producing a reaction product comprising nitrile (referred to as a reaction step), and spraying a spray liquid to the reaction product by a spray device to cool the reaction product (referred to as a cooling step), wherein the spray device comprises a spray liquid inlet, a first spray pipe fluidly connected to the spray liquid inlet, a plurality of (such as 10-26, preferably 12-22) second spray pipes fluidly connected to the first spray pipe and extending perpendicularly to the first spray pipe to both sides thereof, a plurality of (such as 4-26, preferably 6-22) third spray pipes fluidly connected to the second spray pipe and extending perpendicularly to the second spray pipe to both sides thereof, and a nozzle disposed at the end of the third spray pipe and in fluid communication therewith, wherein in the cooling step, the spray liquid input pressure of the spray liquid inlet is controlled to be 0.06-1.00 MPaG (preferably 0.12-0.90 MPaG, more preferably 0.18-0.80 MPaG).

2. The manufacturing method according to claim 1, wherein the plurality of second spray pipes extend perpendicularly to the first spray pipe and substantially parallel to its opposite sides along the horizontal direction, and / or the plurality of third spray pipes extend perpendicularly to the second spray pipe and substantially parallel to its opposite sides along the horizontal direction.

3. The manufacturing method according to claim 1, wherein the inner diameter of the first spray pipe is 160-480 mm (preferably 200-450 mm) and the length is 4500-11500 mm (preferably 4800-10500 mm), and / or the multiple second spray pipes are the same or different from each other, and the inner diameters are each independently 30-150 mm (preferably 40-120 mm) and the lengths are each independently 1200-5750 mm (preferably 1800-5250 mm), and / or the multiple third spray pipes are the same or different from each other, and the inner diameters are each independently 10-60 mm (preferably 15-50 mm) and the lengths are each independently 160-325 mm (preferably 175-300 mm).

4. The manufacturing method of claim 1, wherein the nozzles are the same or different from each other, the inner diameter (referring to the nozzle outlet) is independently 3-20 mm (preferably 6-14 mm), the diameter of the rotating chamber is independently 10.0-55.0 mm (preferably 13.0-45.0 mm), and the spraying angle is independently 65-120° (preferably 70-100°).

5. The manufacturing method according to claim 1, wherein on the first spray pipe, the horizontal spacing between two adjacent second spray pipes is 640-1300 mm (preferably 700-1200 mm), and / or, on the same second spray pipe, the horizontal spacing between two adjacent third spray pipes is 320-650 mm (preferably 350-600 mm), and / or, on two adjacent second spray pipes, the straight-line distance M between the end of any third spray pipe on one second spray pipe and the end of any third spray pipe on another adjacent second spray pipe is not less than 320 mm (preferably not less than 350 mm).

6. The manufacturing method according to claim 1, wherein the nozzles are the same or different from each other, and the spray liquid spraying amount is independently 0.5-7.5t / h (preferably 0.9-6.5t / h), and / or, the nozzles are the same or different from each other, and the spray liquid spraying pressure at the nozzle outlet is independently 0.03-0.85MPaG (preferably 0.04-0.65MPaG).

7. The production method according to claim 1, wherein in the cooling step, the spraying liquid contacts the reaction product in a countercurrent manner.

8. The manufacturing method according to claim 1, wherein in the cooling step, the flow ratio of the spraying liquid to the reaction product is 15-25:

1.

9. The manufacturing method of claim 1, wherein the cooling step is carried out in an absorption device, and a plurality (e.g., 2-10, preferably 4-8) of the spraying devices are layered inside the absorption device at a predetermined vertical spacing along the central axis direction of the absorption device.

10. The manufacturing method according to claim 9, wherein when a cross section is obtained by cross-cutting the absorption device in a direction perpendicular to the central axis of the absorption device, a projection of at least one (preferably all) of the first spray pipe, the second spray pipe and the third spray pipe selected from one of the multiple spray devices and another of the multiple spray devices on the cross section substantially coincides.

11. The manufacturing method according to claim 10, wherein the projections of all nozzles of the one spraying device and the other spraying device on the cross section substantially overlap, and / or the two nozzles whose projections substantially overlap have the same spray diameter.

12. The manufacturing method according to claim 9, wherein the vertical distance between two adjacent spraying devices (measured by the vertical distance between the spraying liquid inlets of the spraying devices) is 650-1350 mm (preferably 750-1200 mm).

13. The manufacturing method according to claim 9, wherein the difference (absolute value) in the spray liquid input pressure of any two spray liquid inlets of the spraying devices is less than 0.024 MPa (preferably less than 0.018 MPa, more preferably less than 0.012 MPa).

14. The production method according to claim 9, wherein the inner diameter of the absorption device is 4.5-11.5 m (preferably 4.8-10.5 m).

15. The production method according to claim 1, wherein in the reaction step, the hydrocarbon feedstock is propylene, the molar ratio of propylene / ammonia / air (in terms of 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 weight hourly space velocity is 0.06-0.15 h -1 Alternatively, the hydrocarbon feedstock is isobutylene, the molar ratio of isobutylene / ammonia / air (in terms of 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 hourly space velocity is 0.08-0.17 h -1 .

16. The manufacturing method of claim 1, wherein in the cooling step, the spraying liquid cools the temperature of the reaction product from 425-445°C (or 390-420°C) to 81-86°C (or 87-95°C), and / or, in the cooling step, the spraying liquid reduces the ammonia content of the reaction product to below 150 ppm.

17. A nitrile manufacturing device, comprising a reactor, an absorption device and a pressure controller, wherein the reactor is constructed to cause ammoxidation reaction of a hydrocarbon feedstock to produce a reaction product containing nitrile, the absorption device is constructed to spray a spray liquid onto the reaction product through a plurality of spray devices arranged therein to cool the reaction product, wherein each of the spray devices independently comprises a spray liquid inlet, a first spray pipe fluidly connected to the spray liquid inlet, a plurality of second spray pipes fluidly connected to the first spray pipe and extending perpendicularly to the first spray pipe to both sides thereof, a plurality of third spray pipes fluidly connected to the second spray pipe and extending perpendicularly to the second spray pipe to both sides thereof, and a nozzle located at the end of the third spray pipe and fluidly connected thereto, and the pressure controller is constructed to control the spray liquid input pressure of the spray liquid inlet of each of the spray devices to be within 0.06-1.00MPaG (preferably 0.12-0.90MPaG, more preferably 0.18-0.80MPaG).

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