Absorption device with gas cavity and nitrile manufacturing method

Abstract

The invention relates to an absorption device with a gas cavity and a manufacturing method of nitrile. According to the absorption device, gas-phase ammonia can be uniformly dispersed on the cross section of the tower, and the ammonia absorption efficiency can be improved. The absorption device comprises a shell, a gas inlet and a spraying device arranged in the shell; 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 spraying device comprises a second spraying pipe, a plurality of third spraying pipes which are in fluid communication with the second spraying pipe, are perpendicular to the second spraying pipe and extend towards the two sides of the second spraying pipe, and nozzles which are located at the tail ends of the third spraying pipes and are in fluid communication with the third spraying pipes, and the gas inlet is located below the spraying device in the direction of the central axis of the absorption device; and the vertical distance between the gas inlet and the spraying liquid inlet of the spraying device is 800-6000 mm.

Description

Technical Field

[0001] The present invention relates to the technical field of gas absorption, and more particularly to an absorption device with a gas cavity and a method for producing nitrile. 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] In a one-stage ammonia absorption tower, ammonia-containing gas enters the tower along the inlet semicircular pipe line, and the gas moves from bottom to top, and contacts the acidic circulating liquid in reverse, during which the gas phase ammonia is neutralized by acid. Since the ammonia in the gas phase of the existing device is unevenly distributed on the cross section in contact with the first layer of acidic circulating liquid in the tower, the ammonia is also unevenly distributed on the cross section at each axial position during the gas rising process. Usually, the ammonia absorption rate in the area with relatively high ammonia content is met by increasing the concentration of circulating liquid acid. Therefore, the acid consumption in the existing device is relatively high. Summary of the invention

[0006] The inventors of the present invention have found that this problem can be solved by setting the vertical distance between the gas inlet and the spray liquid inlet within a specific numerical range. The present invention has been completed based on this finding.

[0007] In the first embodiment, the present invention relates to an absorption device, comprising a shell, a gas inlet and a spraying device arranged inside the shell, wherein the spraying 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 on both sides thereof, a plurality of third spray pipes fluidly 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 fluidly connected thereto, the gas inlet is located below the spraying device along the central axis direction of the absorption device, and the vertical distance between the gas inlet and the spray liquid inlet of the spraying device is 800-6000mm.

[0008] In a second embodiment, the present invention relates to a method for producing a nitrile, comprising the following steps: subjecting a hydrocarbon feedstock to an ammoxidation reaction to produce a reaction product containing a nitrile (referred to as a reaction step), and inputting the reaction product into the absorption device from a gas inlet of the absorption device, and spraying a spray liquid onto the reaction product by a spray device arranged inside the absorption device to cool the reaction product (referred to as a cooling step), wherein the absorption device is the absorption device described in the first embodiment.

[0009] Technical Effects

[0010] According to the absorption device of the present invention, the gaseous ammonia is distributed more uniformly in the ammonia absorption tower.

[0011] According to the absorption device of the present invention, the gaseous ammonia contacts the acidic liquid more fully, and the ammonia absorption is more complete.

[0012] According to the absorption device of the present invention, the usage amount of acid is reduced. 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 4A , Figure 4B 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 top view schematic diagram of the 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] 23: Gas distributor 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 an absorption device, in particular an ammonia absorption tower or a quenching tower. The absorption device is particularly suitable for use as an absorption device in the production of (meth)acrylonitrile.

[0051] According to one embodiment of the present invention, the absorption device comprises a shell, a gas inlet and a spraying device arranged inside the shell.

[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, the gas inlet is located below the spraying device along the central axis direction of the absorption device.

[0057] According to one embodiment of the present invention, the vertical distance between the gas inlet and the spraying liquid inlet of the spraying device (when there are multiple, it refers to the spraying device closest to the gas inlet) is 800-6000mm (preferably 1000-5000mm). The inventor of the present invention found that the gas enters the tower from the inlet along the semicircular inlet pipe that bends downward to the bottom of the tower, and then moves from bottom to top. Relatively speaking, the gas concentration is the highest at the inlet pipe. While the gas is going up, due to the difference in gas concentration, the gas diffuses to the surrounding area, and finally the gas concentration on the cross section of the tower reaches uniformity. If the vertical distance is less than 800mm, the gas concentration is prone to insufficient diffusion, and the concentration varies, which is easy to cause incomplete local ammonia absorption and local acid excess; if the vertical distance is too large, on the one hand, the tangent height of the ammonia absorption tower is too high, increasing equipment investment. On the other hand, during the rotating falling process of the spraying liquid, the two colliding droplets have behaviors such as separation, polymerization, and fragmentation, and when polymerization occurs, larger droplets are formed; when fragmentation occurs, smaller droplets are formed. The longer the distance the droplets are sprayed, the easier it is for them to aggregate or break, which is also not conducive to the absorption of ammonia.

[0058] According to a preferred embodiment of the present invention, the linear velocity of the gas inside the shell is 0.6-1.5m / s (preferably 0.7-1.3m / s). The inventors of the present invention have found that the operating speed inside the shell affects the gas diffusion speed. The greater the operating speed inside the shell, the stronger the turbulence effect, which is conducive to the diffusion of the gas, and therefore, the shorter the diffusion distance. When the speed inside the shell is lower than 0.6, relatively speaking, it takes a long time for the gas to diffuse uniformly, that is, the distance from the inlet to the first layer of the spraying device increases. However, when the linear velocity inside the shell is higher than 1.5m / s, since the droplets of the spraying liquid of the spraying device are usually in the form of droplets with a particle size of 50-5000μm, these droplets are easily entrained by the gas. The greater the speed inside the shell, the more serious the entrainment of the mist, resulting in more droplets containing ammonium salts being carried away from the ammonia absorption tower by the gas.

[0059] 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.

[0060] 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.

[0061] 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).

[0062] 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).

[0063] 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).

[0064] According to one embodiment of the present invention, the nozzles are the same or different from each other, and the inner diameter (referring to the nozzle outlet) is independently 3-20 mm (preferably 6-14 mm).

[0065] According to one embodiment of the present invention, the diameter of the rotating chamber of the nozzle is independently 10.0-55.0 mm (preferably 13.0-45.0 mm), and the spraying angle of the nozzle 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 particular limitation.

[0066] According to one embodiment of the present invention, on the first spray pipe, the horizontal distance between two adjacent second spray pipes is 640-1300 mm (preferably 700-1200 mm).

[0067] 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).

[0068] According to one embodiment of the present invention, on two adjacent second spray pipes, the straight-line distance M (e.g., Fig. 6A , Figure 6BThe 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.

[0069] According to one embodiment of the present invention, the nozzles are the same 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).

[0070] According to one embodiment of the present invention, the inner diameter of the gas inlet is 800-1900 mm (preferably 900-1700 mm).

[0071] According to one embodiment of the present invention, the inner diameter of the absorption device is 4.5-11.5m (preferably 4.8-10.5m). The inventors of the present invention have found that for an absorption tower of the same device scale, if the inner diameter is too small, the ammonia absorption will not be complete due to insufficient gas-liquid contact time, resulting in ammonia escaping from the absorption tower; if the inner diameter is too large, the stroke of the circulating liquid in the spraying device will increase, and the end of the third spraying pipe in the remote area will have low pressure and poor liquid atomization, resulting in ammonia escaping from this area.

[0072] According to a preferred embodiment of the present invention, the internal space of the absorption device between the gas inlet and the spraying device (when there are multiple, it refers to the spraying device closest to the gas inlet) is not provided with mechanical components that can substantially affect the flow of the gas, such as mechanical components that disturb the flow of the gas, especially baffles, trays, fillers, etc. The inventors of the present invention have found that although the gas phase ammonia can be evenly dispersed on the cross section before contacting the first layer of spray liquid by adding internal components, no matter what type of mechanical components are used, the system pressure of the device will be increased, which will eventually be reflected in the increase of reaction pressure and the reduction of the yield of the target product. The smaller the droplet size, the larger the contact surface between the droplet and the gas ammonia, and the better the absorption effect. Conversely, the ammonia absorption effect is worse. Usually, the ammonia absorption efficiency of the first layer spraying device is relatively the highest. As mentioned above, the droplet particle size is 50-5000μm, and the ammonia absorption efficiency of the first layer spraying device is 30-55% or even higher. If the droplet is too large, the ammonia absorption efficiency of the first layer is significantly reduced, thereby affecting the overall absorption efficiency. Gas is relatively easy to diffuse, and even if the gaseous ammonia is not completely dispersed and uniform at the first layer of spraying position, the gaseous ammonia will continue to diffuse during the rising process and will be captured and absorbed by the spraying liquid of the subsequent layers of spraying devices. Therefore, adding components here, although the purpose of rapid and uniform dispersion of gaseous ammonia is met, the vertical distance from the first layer of spraying devices to the inlet is 800-6000mm, preferably 1000-5000mm, which can meet the high efficiency reaction of the previous reaction stage and the absorption efficiency of ammonia in this tower, and is more economical for the entire device.

[0073] According to one embodiment of the present invention, a plurality (eg, 2-10, preferably 4-8) of the spraying devices are arranged in layers along the central axis direction of the absorption device at a predetermined vertical interval.

[0074] 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.

[0075] 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.

[0076] According to one embodiment of the present invention, two nozzles whose projections substantially coincide with each other have the same spray diameter.

[0077] According to one embodiment of the present invention, the vertical distance between two adjacent spraying devices (measured as the vertical distance between the spraying liquid inlets of the spraying devices) is 650-1350 mm (preferably 750-1200 mm).

[0078] According to one embodiment of the present invention, it also relates to a method for producing nitrile, in particular, a method for producing (meth)acrylonitrile.

[0079] According to one embodiment of the present invention, the method for producing the nitrile comprises the following steps:

[0080] subjecting a hydrocarbon feedstock to an ammoxidation reaction to produce a reaction product comprising a nitrile (referred to as a reaction step), and

[0081] The reaction product is fed into the absorption device from the gas inlet of the absorption device, and a spraying liquid is sprayed on the reaction product by a spraying device arranged inside the absorption device to cool the reaction product (referred to as a cooling step). According to the present invention, the absorption device is an absorption device as described in any of the above embodiments. For this reason, the contents not described in detail here can be directly referred to the relevant contents described above for the absorption device.

[0082] 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 -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 .

[0083] 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).

[0084] 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.

[0085] According to one embodiment of the present invention, the flow ratio of the spraying liquid to the reaction product is 15-25:1.

[0086] A specific embodiment of the present invention is described in detail below by way of example with reference to the accompanying drawings.

[0087] like Figure 4AAs 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 multi-layer spraying devices 3a-3f through the circulating pump 17. The spraying devices 3a-3f are arranged in sequence from top to bottom in the tower, 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 ammonia-containing gas feed port 8 and the spraying device 3f are arranged in sequence from top to bottom in the tower. The vertical distance is 1800mm; the acid-containing liquid is added to the circulating pump outlet pipeline from the acid solution port 15, and the circulating liquid passes through the spray device 3, enters from the inlet 18 of the spray device 3, and 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, absorbing 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.

[0088] Example

[0089] The present invention is further described in detail below using examples, but the present invention is not limited to these examples.

[0090] Example 1

[0091] Ammonia absorption tower Figure 3B The absorption tower has a two-stage structure, the inner diameter of the absorption tower is 7200 mm, and there is no gas distributor 23 in the tower. The linear velocity of the reaction gas in the tower is 1.1 m / s. The acid added to the circulating liquid is sulfuric acid. The acid-containing circulating liquid is delivered to the absorption tower through 4 spraying devices via the upper circulating pump. The vertical distance from the gas inlet to the spraying device 3d is 4000 mm, the inner diameter of the gas inlet is 1300 mm, and the interval between two adjacent spraying devices is 1200 mm. Each spraying device has 16 second spraying pipes, and the second spraying pipe is 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 pipes 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 pipes 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 projections of the third spray ends of the spray device overlap, and the adjacent two third spray pipes are as follows Figure 6BThe end distance shown is 580mm; the spraying 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 spraying amount of each nozzle is 4.8t / h, and the weight ratio of the spray liquid to the reaction gas entering from the gas inlet is 20. The residual ammonia concentration of the tail gas from the reaction outlet is 41ppm, and the amount of sulfuric acid added from the acid solution port 15 (kg / h): the amount of ammonia entering from the gas phase feed port 8 (kg / h) is 2.07.

[0092] Example 2

[0093] Ammonia absorption tower Figure 4A The absorption tower has a one-stage structure, the inner diameter of the absorption tower is 7200 mm, and there is no gas distributor 23 in the tower. The linear velocity of the reaction gas in the tower is 1.1 m / s. The acid added to the circulating liquid is sulfuric acid. The circulating liquid containing the acid is delivered to the absorption tower through 6 spraying devices via a circulating pump. The vertical distance from the gas inlet to the spraying device 3f is 1500 mm, the inner diameter of the gas inlet is 1300 mm, and the vertical spacing between two adjacent spraying devices is 880 mm. Each spraying device has 14 second spraying pipes, and the second spraying pipe is 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 of the second spray pipe 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 of the third spray pipe is 250mm. The projections of the third spray ends of the spray device overlap. If two adjacent third spray pipes are Figure 6B The end distance shown is 707 mm. The spraying device has a total of 912 nozzles, the nozzle outlet diameter is 11.7 mm, the nozzle rotation chamber diameter is 36 mm, the nozzle spray angle is 80°, the spray liquid spraying amount of each nozzle is 5.1 t / h, and the weight ratio of the spray liquid to the reaction gas entering from the gas inlet is 20. The residual ammonia concentration of the tail gas from the reaction outlet is 27 ppm, and the amount of sulfuric acid added from the acid solution port 15 (kg / h): the amount of ammonia entering from the gas phase feed port 8 (kg / h) is 2.06.

[0094] Example 3

[0095] Same as Example 2, except that the vertical distance from the gas inlet to the spraying device 3f is 900 mm.

[0096] The residual ammonia concentration of the tail gas from the reaction outlet is 130 ppm, the amount of sulfuric acid added from the acid solution inlet 15 (kg / h): the amount of ammonia entering from the gas phase feed inlet 8 (kg / h) is 2.18.

[0097] Example 4

[0098] The same as Example 2, the only difference is that the spraying devices 3a-3f are on the same side of the absorption tower, such as Figure 2 shown.

[0099] The residual ammonia concentration of the tail gas from the reaction outlet is 85 ppm, the amount of sulfuric acid added from the acid solution inlet 15 (kg / h): the amount of ammonia entering from the gas phase feed inlet 8 (kg / h) is 2.23.

[0100] Example 5

[0101] The same as Example 2, the only difference is that the inner diameter of the absorption tower is 12500mm, the inner diameter of the gas inlet is 1900mm, each spraying device has 24 second spraying pipes, and the second spraying pipe is provided with 10 to 24 third spraying pipes. The inner diameter of the first spraying pipe of the spraying device is 550mm, and the length of the first spraying pipe is 12100mm; the inner diameter of the second spraying pipe is 140mm, and the length of the second spraying pipe is 2800mm-6150mm; the spraying device has a total of 2736 nozzles. The residual ammonia concentration of the tail gas from the reaction outlet is 105ppm, and the amount of sulfuric acid added from the acid solution port 15 (kg / h): the amount of ammonia entering from the gas phase feed port 8 (kg / h) is 2.15.

[0102] Example 6

[0103] The same as Example 2, the only difference is that a gas distributor 23 is provided in the tower, such as Figure 4B The residual ammonia concentration of the tail gas from the reaction outlet is shown to be 35ppm, and the amount of sulfuric acid added from the acid solution port 15 (kg / h): the amount of ammonia entering from the gas phase feed port 8 (kg / h) is 2.08. After adding the gas distribution internals, the pressure of the ammonia absorber kettle increased by 10KPa, resulting in an increase in the reaction pressure of the ammonia absorber front system by 10KPa, and the yield of the target product nitrile decreased by 1.5%

[0104] Example 7 is the same as Example 2, except that each spraying device has 22 second spraying pipes, and the second spraying pipes are provided with 11 to 22 third spraying pipes. The spacing between the second spraying pipes of the spraying device is 600 mm, and the spacing between the third spraying pipes of the spraying device is 300 mm. The inner diameter of the third spraying pipe is 40 mm, and the length of the third spraying pipe is 150 mm. The spacing between two adjacent third spraying pipes is 600 mm. Figure 6B The end distance shown is 300 mm. The spraying device has a total of 2448 nozzles. The residual ammonia concentration of the tail gas from the reaction outlet is 76 ppm, and the amount of sulfuric acid added from the acid solution port 15 (kg / h): the amount of ammonia entering from the gas phase feed port 8 (kg / h) is 2.16.

[0105] Example 8

[0106] The same as Example 2, the only difference is that the linear velocity of the reaction gas in the tower is 0.5 m / s, the residual ammonia concentration of the tail gas from the reaction outlet is 78 ppm, the amount of sulfuric acid added from the acid solution inlet 15 (kg / h): the amount of ammonia entering from the gas phase feed inlet 8 (kg / h) is 2.18.

[0107] Comparative Example 1

[0108] Same as Example 2, except that the distance from the gas inlet to the spraying device 3f is 500 mm.

[0109] The residual ammonia concentration of the tail gas from the reaction outlet is 350 ppm, the amount of sulfuric acid added from the acid solution inlet 15 (kg / h): the amount of ammonia entering from the gas phase feed inlet 8 (kg / h) is 2.40.

[0110] Comparative Example 2 is the same as Example 2, except that the spraying devices 3a-3f are on the same side of the absorption tower. Figure 2 The distance from the gas inlet to the spraying device 3f is 7000 mm, the residual ammonia concentration of the tail gas from the reaction outlet is 166 ppm, the amount of sulfuric acid added from the acid solution port 15 (kg / h): the amount of ammonia entering from the gas phase feed port 8 (kg / h) is theoretically 2.34.

[0111] As the total height of the tower equipment increases, the equipment investment cost increases, and at the same time, the difficulty of maintenance of the device is also increased.

Claims

1. An absorption device, comprising a shell, a gas inlet and a spraying device arranged inside the shell, wherein the spraying device comprises a spray liquid inlet, a first spray pipe fluidly connected to the spray liquid inlet, a plurality of (e.g., 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 (e.g., 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 located at the end of the third spray pipe and fluidly connected to the third spray pipe, the gas inlet is located below the spraying device along the central axis direction of the absorption device, and the vertical distance between the gas inlet and the spray 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).

2. The absorption device according to claim 1, wherein the plurality of second spray pipes extend substantially parallel to the opposite sides of the first spray pipe perpendicularly to the first spray pipe, and / or the plurality of third spray pipes extend substantially parallel to the opposite sides of the second spray pipe perpendicularly to the second spray pipe.

3. The absorption device 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 plurality of second spray pipes are the same or different from each other, and the inner diameters are independently 30-150 mm (preferably 40-120 mm) and the lengths are independently 1200-5750 mm (preferably 1800-5250 mm), and / or the plurality of third spray pipes are the same or different from each other, and the inner diameters are independently 10-60 mm (preferably 15-50 mm) and the lengths are independently 160-325 mm (preferably 175-300 mm).

4. The absorption device according to 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 rotation 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 absorption device 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 second spray pipe is not less than 320 mm (preferably not less than 350 mm).

6. The absorption device according to claim 1, wherein the nozzles are the same or different from each other, and the spraying amount of the spraying liquid is independently 0.5-7.5 t / h (preferably 0.9-6.5 t / h).

7. The absorption device according to claim 1, wherein the inner diameter of the gas inlet is 800-1900 mm (preferably 900-1700 mm), and / or the inner diameter of the absorption device is 4.5-11.5 m (preferably 4.8-10.5 m), and / or the linear velocity of the gas inside the shell is 0.6-1.5 m / s (preferably 0.7-1.3 m / s).

8. The absorption device according to claim 1, wherein 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) is not provided with any mechanical components that can substantially affect the flow of the gas.

9. The absorption device according to claim 1, wherein a plurality (such as 2-10, preferably 4-8) of the spraying devices are arranged in layers along the central axis direction of the absorption device at a predetermined vertical interval.

10. The absorption device of claim 9, wherein when a cross section is obtained by 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 absorption device 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 absorption device 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. A method for producing nitrile, comprising the steps of: subjecting a hydrocarbon feedstock to an ammoxidation reaction to produce a reaction product comprising a nitrile (referred to as a reaction step), and The reaction product is introduced into the absorption device from the gas inlet of the absorption device, and a spraying liquid is sprayed on the reaction product by a spraying device disposed inside the absorption device to cool the reaction product (referred to as a cooling step), The absorption device is the absorption device according to claim 1.

14. The production method according to claim 13, 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 .

15. The manufacturing method of claim 13, 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.

16. The manufacturing method according to claim 13, wherein the flow ratio of the spraying liquid to the reaction product is 15-25:1.

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