TWI666060B - Improved air grid design for an oxidation or ammoxidation reactor - Google Patents

Abstract

Commercial acrylonitrile reaction when the distance between the spreader system 16 and the air grille 14 is controlled within 6 to 24 inches (~ 15 to ~ 61cm), preferably 8 to 12 inches (~ 20 to ~ 30.5cm) Inadequate reactant mixing in the reactor and local reactor hot spots can be significantly reduced. In addition, the movement of the air grid in contact with or away from the support and the mechanical failure of the air grid can be substantially completely solved by means of an improved system for attaching the air grid to the wall of the reactor and the support beams inside it To eliminate.

Description

Improved air grill design for oxidation or ammonia oxidation reactors

The present invention is an improved air grill design for an oxidation or ammonia oxidation reactor.

Background of the invention

In the commercial manufacture of acrylonitrile, propylene, ammonia and oxygen react together according to the following reaction scheme: CH ₂ = CH-CH ₃ + NH ₃ +3/2 O ₂ → CH ₂ = CH-CN + 3 H ₂ O This process, known as ammoxidation, is carried out in the gas phase at elevated temperatures in the presence of a suitable fluidized bed ammoxidation catalyst.

Figure 1 shows a typical ammoxidation reactor used to perform this process. As shown in the figure, the reactor 10 includes a reactor wall 12, an air grid 14, a feed sparger 16, a cooling coil 18, and a cyclone 20. During normal operation, process air is charged into the reactor 10 through an air inlet 22 and a mixture of propylene and ammonia is charged into the reactor 10 through a feed distributor 16. The flow rates of both are high enough to fluidize the bed 24 of ammonia oxidation catalyst inside the reactor, in which catalytic ammoxidation of propylene and ammonia to acrylonitrile occurs.

The product gas produced by the reaction passes through the reactor effluent outlet 26 leaves the reactor 10. Before doing so, the product gas passes through a cyclone 20 which removes any ammonia oxidation catalysts that these gases can entrain to return to the catalyst bed 24 through diplegs 25. Ammonia oxidation is highly exothermic, so the cooling coil 18 is used to remove excess heat, thereby maintaining the reaction temperature at an appropriate level.

Propylene and ammonia can form explosive mixtures with oxygen. However, in positive At normal operating temperatures, a fluidized amination catalyst is used to prevent explosion inside the reactor 10, and the catalyst preferentially catalyzes the ammonia oxidation reaction before an explosion can occur. Accordingly, the reactor 10 is designed and operated such that the only place where process air is allowed to contact propylene and ammonia during normal operation is within the fluidized bed of the ammonia oxidation catalyst 24, and therefore only when the temperature of the catalyst is high enough to catalyze ammonia During the oxidation reaction.

To this end, the conventional way of feeding propylene and ammonia to the reactor 10 is to use With a feed distributor system 16 such as shown in U.S. 5,256,810, the disclosure of this patent is incorporated herein by reference. As shown in Figures 1 and 2 of the '810 patent (both figures are renumbered as Figures 2 and 3 of this document), the feed distributor 16 takes the form of a series of supply tubes or pipes, which include the main The header 30 and a lateral pipe 32 are attached to and branched from the header 30. A series of downwardly facing feed nozzles 34 are defined in the header 30 and the branch pipe 32, and a mixture of propylene and ammonia is charged through the feed nozzles 34 during normal reactor operation. The number and spacing of the branch pipes 32 and the feed nozzles 34 are such that a total of about 10 to 30 feed nozzles per square meter are positioned approximately uniformly across the entire cross-sectional area of the reactor 10.

Generally, each feed nozzle 34 is surrounded by a feed shroud 36. The material shield 36 takes the form of a short section of a pipe whose inner diameter is several times the diameter of the nozzle 34. The feed shroud 36 enables the velocity of the gas exiting the nozzle 34 to be significantly slowed before leaving the catalyst bed 24, which prevents disintegration of the catalyst that could otherwise occur.

Process air typically enters the catalyst after passing through the air grill 14 The agent bed 24 (FIG. 1) and the air grid 14 are located below the feed distributor 16. As is well known, the air grid 14 typically takes the form of a continuous sheet of metal that defines a series of air holes or nozzles therein. The diameter of the air nozzle, the mass flow of the process air through the air grid 14, and the mass flow of the propylene / ammonia mixture through the feed distributor 16 are selected such that the ammonia oxidation catalyst in the catalyst bed 24 is removed during normal operation These gases are completely fluidized.

The air hole 76 (in FIG. 5) is usually provided with its own protective cavity An air shroud (not shown), which is usually located under the air grill 14. In addition, in many cases, the feed nozzles 34 are arranged in a one-to-one relationship with the air nozzles in the air grill 14, where each feed shroud 36 is directly aligned with its corresponding air nozzle to facilitate the Fast and thorough mixing of gases from two different nozzles. For the purposes of this application, such air nozzles are referred to as capless. See U.S. 4,801,731. In other cases, the air nozzle may have a cover mounted directly above it to preferentially distribute the air horizontally (in an directional or uniform manner) along the grill rather than vertically facing the feed shroud. These covers may be small metal covers welded over such air nozzles. The design of the legs that attach the cover to the grille can be selected to optimize the horizontal gas distribution pattern. These covers above the air holes can also be designed to prevent the catalyst in a defluidized state (i) from falling through the air holes and / or (ii) from settling on the cover itself (e.g. (Eg, by having a slope or made of angle iron).

Although this general type of propylene / ammonia feed system works well Good, but it can have certain disadvantages. For example, mixing of the propylene / ammonia feed mixture exiting the feed distributor 16 with air exiting the air grill 14 may be insufficient. This can reduce reactor performance, resulting in less desirable conversion of reactants to products.

In addition, the molybdenum scale produced by the ammonia oxidation catalyst (molybdenum scale) can cause a small pile of this molybdenum scale plus an additional amount of entrained catalyst to accumulate on the upper surface of the air grid 14 in the form of a small catalyst pile. These stacks act like miniature stationary or "fixed" catalyst beds where the ammoxidation reaction continues. Because the heat transfer inside a fixed catalyst bed is much weaker than in a fluidized bed, these catalyst stacks generate local hot spots that are high enough to damage any fluidized catalyst that just arrives nearby. For example, such a temperature is high enough to calcinate to the surface of any nearby fluidized catalyst, which in turn reduces surface area and therefore catalyst activity. And, since the individual catalyst particles forming the fluidized catalyst bed freely circulate through its entire volume, over time these hot spots can damage all the charge of the fluidized bed catalyst in the reactor.

Additional disadvantages include mechanical problems with the structure of the acrylonitrile reactor. question. Typical commercial acrylonitrile reactors operate at relatively constant temperatures of about 400 to 550 ° C, but fluctuations do occur. In addition, the ammonia oxidation reactor must be shut down periodically for normal maintenance, catalyst replacement, etc., and due to sudden failures, such as, for example, a power failure. Because the normal operating temperature is so high, when the reactor turns between ambient and normal operating temperatures As the temperature changes, the temperature inside the reactor can change as high as 500 ° C or more. This cycling between low and high temperatures can place considerable stress on the structural members forming the reactor, especially where they are connected to each other, as the inherent expansion and contraction of these structural members occurs in response to temperature changes . Over time, these stresses can cause mechanical failure, especially at joints formed by welding.

For example, the air grid 14 is attached to the normal wall 12 of the reactor 10 The mode is shown in FIG. 4. As shown, an air grill 14 is attached to the side wall 12 of the reactor by knuckle 44 in the form of a substantially flat metal plate 40 having a series of holes therein. As shown in the figure, the chamfer 44 takes the form of a metal concave cross section in cross section, its upper end 46 is substantially flush with the side wall 12 and is welded to the side wall 12 by a weld 48, and its lower end 50 is connected to the air grid. The facing edge of the grid plate 40 is substantially coplanar and is welded to the edge by a weld 52.

Large commercial acrylonitrile reactor with a diameter of 31 feet (~ 9.4 meters) For example, the air grid plate 40 may expand and contract horizontally up to ½ inch (1.27 cm) in response to temperature changes experienced during reactor startup and shutdown. This creates significant stress on the chamfer 44 and especially the welds 48 and 52 used to attach the chamfer 44 to the air grill plate 40 and the reactor side wall 12. Unfortunately, these stresses can cause mechanical failure over time, which in turn requires long downtimes for repairs and / or replacements.

Another disadvantage associated with the above conventional design involves air The grill is flexing. Since the air grid 16 must support the entire weight of the catalyst charge inside the reactor 10 when the reactor 10 is stopped, it needs to be supported from below The air grill plate 40 is supported to accommodate the weight. Usually, this is achieved by means of an I-beam system on which the air grille panel 40 rests. In some reactor designs, the air grid plate 40 rests only on these I-beams. Unfortunately, in these designs, the air grill plate 40 has a tendency to vibrate during normal operation, not only due to the force of the air moving upward through the air grill plate, but also because when its temperature rises to normal Its inherent expansion at operating temperature. In other designs, the air grille plate 40 is welded to the top of these I-beams. Unfortunately, in these designs, the force of the air moving upwards coupled with the inherent expansion of the air grille plate can cause mechanical failure of these welds.

Summary of invention

According to the technology of the present disclosure, it has been found that when the distance between the spreader system 16 and the air grille 14 is controlled to 6 to 24 inches (~ 15 to ~ 61cm), preferably 8 to 12 inches (~ 20 to ~ 30.5cm) ), The above problems of inadequate mixing of reactants and excessive hot spots in the local reactor can be significantly alleviated. In addition, it has been found that the above problems of air grill flutter and mechanical failure of the air grill can be substantially completely solved by means of an improved system for attaching the air grill to the wall of the reactor and the supporting beams inside it To eliminate.

Accordingly, the present disclosure provides an improved feed system for a commercial oxidation or ammonia oxidation reactor, such as an acrylonitrile reactor, according to one feature, including: a feed distributor for feeding unsaturated and / or A mixture of saturated C3 to C4 hydrocarbons and ammonia is supplied to the inside of the reactor; and an air grid system for supplying air to the inside of the reactor, the feed distributor includes a main header pipe and a fluid attached to the main Header pipe and from main header pipe The branch pipe, the main header pipe and the branch pipe are separated from each other and define a downward facing feed nozzle. The feed distributor system also includes a feed shield associated with the corresponding feed nozzle. The hood includes a proximal end that is connected to a corresponding branch or header pipe and is arranged to direct C3 to C4 hydrocarbons and ammonia out of their respective feed nozzles into the interior of the reactor, an air grid system Comprising a continuous metal plate arranged below the feed distributor system, a series of air holes defined therein by the continuous metal plate for directing process air from below the continuous metal plate towards the distributor system to above the continuous metal plate, Wherein the distance between the upper surface of the continuous metal plate and the distal end of the feed shield is selected to be between about 6 to 24 inches (~ 15 to ~ 61 cm). As used herein, a mixture of unsaturated and / or saturated C3 to C4 hydrocarbons refers to C3 to C4 hydrocarbons including propane, propylene, butane, butene, and mixtures thereof.

In another aspect, a method for reacting to oxidation or ammonia oxidation is provided. A method of reactor feed comprising supplying a mixture of saturated and / or unsaturated C3 to C4 hydrocarbons and ammonia to the interior of the reactor through a feed distributor. The feed distributor includes a main header pipe and a branch pipe where fluid is attached to and branched from the main header pipe, and both the main header pipe and the branch pipe define a downward facing feed nozzle. The feed distributor system also includes a feed shroud associated with a respective feed nozzle, each feed shroud including a proximal end that is connected to a corresponding branch pipe or header pipe and is arranged to pass through The saturated and / or unsaturated C3 to C4 hydrocarbons and ammonia of their respective feed nozzles are directed down into the interior of the acrylonitrile reactor. The method also includes supplying air to the interior of the reactor through an air grill system. Air grill system includes A continuous metal plate disposed below the feed distributor system, the continuous metal plate defining a series of air holes therein for directing process air from below the continuous metal plate toward the distributor system to above the continuous metal plate. In one aspect, the distance between the upper surface of the continuous metal plate and the distal end of the feed shield is between about 6 to about 24 inches (about 15 to about 61 cm).

In addition, the present disclosure provides a method for Improved air grid system used in commercial oxidation or ammonia oxidation reactors, such as acrylonitrile reactors, the improved air grid system includes a continuous metal plate that defines an upper surface, a lower surface, and upper and lower surfaces A continuous perimeter extending therebetween, the continuous metal plate also defines a series of air holes for directing process air from below the continuous metal plate toward a distributor feed system located above the continuous metal plate; and a support system for supporting the continuous The weight of the metal plate and any oxidation or ammonia oxidation catalyst that can rest on a continuous metal plate, where the support system includes a series of support beams and a series of support presses fixedly attached to the underside of the continuous metal plate (hold- downs), each support beam has an upper support surface that engages the underside of a continuous metal plate, and each support press is arranged to engage a mating surface defined below its upper surface in the corresponding support beam in such a way that The support press prevents the continuous metal plate from being lifted off into a series of support beams.

In another aspect, a method for reducing commercial oxidation or ammonia is provided. Method of moving an air grid system in an oxidation reactor. The method includes providing an air grill system including a continuous metal plate defining an upper surface, a lower surface, and a perimeter extending between the upper and lower surfaces. The continuous metal plate also defines a method for removing process air from the continuous metal plate. A series of air holes directed down to the top of the continuous metal plate; and a support system to support the weight of the continuous metal plate and any oxidation or ammonia oxidation catalyst that can rest on the continuous metal plate. In one aspect, the support system includes a series of support beams each having an upper support surface that engages a lower side of the continuous metal plate and a series of support presses fixedly attached to the lower side of the continuous metal plate. Each support press is arranged to engage a mating surface defined below its upper surface in a corresponding support beam in such a way that the support press prevents the continuous metal plate from being lifted off into a series of support beams.

In addition, the present disclosure provides a method for Improved air grid system used in commercial oxidation or ammonia oxidation reactors, such as acrylonitrile reactors, the improved air grid system includes a continuous metal plate that defines an upper surface, a lower surface, and upper and lower surfaces A continuous perimeter extending therebetween, the continuous metal plate also defines a series of air holes for directing process air from below the continuous metal plate toward a distributor feed system located above the continuous metal plate; and a connection assembly for placing the The perimeter of the continuous metal plate is attached to the side wall of the oxidation or ammoxidation reactor, where the connection assembly includes a flexible plate and a mating partition, each of which includes an annular metal sheet defining the top and bottom, flexible Both the plate and the partition are arranged to be substantially congruent with the side wall of the oxidation or ammoxidation reactor, where the partition is attached to the side wall of the oxidation or ammoxidation reactor, where the bottom of the flexible plate is attached to a continuous metal plate And wherein the flexible plate is attached to the partition in such a way that the flexible plate defines a lower portion extending below the bottom of the partition so that the temperature is affected by the temperature inside the reactor. Diameter deviation in a continuous sheet of metal may be caused by the lower accommodate flexing of the flexible board.

In another aspect, a method for adapting an air grille system is provided. A method of flexing in a system, the method comprising providing a continuous metal plate defining an upper surface, a lower surface, and a perimeter extending between the upper and lower surfaces. The continuous metal plate also defines a series of air holes for directing process air from below the continuous metal plate to above the continuous metal plate, and a connection assembly for attaching the periphery of the continuous metal plate to the side wall of the reactor. The connection assembly includes a flexible plate and a mating partition, each of which includes an annular metal sheet defining a top and a bottom. Both the flexible plate and the partition are arranged to be substantially consistent with the side wall of the reactor, where the partition is attached to the side wall of the reactor, where the bottom of the flexible plate is attached to the periphery of a continuous metal plate, and where the flexible plate is The flexible plate is attached to the partition in a manner that defines a lower portion extending below the bottom of the partition so that a deviation in the diameter of the continuous metal plate due to a temperature change inside the acrylonitrile can be achieved by flexing the lower portion of the flexible plate To adapt.

10‧‧‧ Reactor

12‧‧‧reactor wall

14‧‧‧air grill

16‧‧‧Feed distributor

18‧‧‧ cooling coil

20‧‧‧ Cyclone

22‧‧‧air inlet

24‧‧‧ catalyst bed

25‧‧‧ feed leg

26‧‧‧Reactor effluent outlet

30‧‧‧ Collector

32‧‧‧ branch pipe

34‧‧‧feed nozzle

36、60‧‧‧Feeding shield

40‧‧‧air grille

44‧‧‧Folding angle

46‧‧‧upper

48, 52‧‧‧ Welds

50‧‧‧ lower end

62‧‧‧ proximal

64‧‧‧ remote

70‧‧‧ continuous metal plate

72, 86‧‧‧ Top surface

74‧‧‧ lower surface

76‧‧‧air hole

80‧‧‧ support system

82‧‧‧I-beam, support beam

84‧‧‧ Upper transverse section

88‧‧‧ mating surface

90‧‧‧ support bar

92‧‧‧ protrusion

94, 96‧‧‧ space

100‧‧‧ Connected components

102‧‧‧flexible plate

104‧‧‧ partition

110, 112‧‧‧ bottom

114‧‧‧lower

FIG. 1 is a schematic diagram showing a reactor section of a conventional ammoxidation reactor for preparing acrylonitrile; FIG. 2 is a plan view showing a lower side of the conventional sparger system of the ammoxidation reactor of FIG. 1 Figure 3 is a cross-sectional view taken along line 3-3 of Figure 2, which shows the feed nozzle and associated feed shroud of the conventional distributor system of Figure 2; Figure 4 shows the acrylonitrile reactor Conventional manner of attaching an air grid to the wall of the reactor; FIG. 5 is a partial cross-sectional view of an acrylonitrile reactor showing the The first feature, in which the performance of a conventional acrylonitrile reactor is improved and the mechanical damage to certain components of the acrylonitrile reactor is reduced by spacing the air grid and the feed distributor a suitable distance from each other; 6 illustrates a second feature of the present disclosure in which a new support system for supporting an air grill of an acrylonitrile reactor is provided; and FIG. 7 illustrates a third feature of the present disclosure in which an acrylonitrile reaction is provided The air grid 14 of the reactor is fixed to the unique connection assembly of the side wall of the reactor.

detailed description

FIG. 5 illustrates a first feature of the technology of the present disclosure in which the air grille 14 is spaced a suitable distance from the feed distributor 16, particularly 6 to 24 inches (~ 15 to ~ 61 cm). Specifically, as shown, the feed distributor 16 includes a plurality of feed shrouds 60, each feed shroud being associated with a corresponding feed nozzle defined in a header 30 or branch pipe 32 of the distributor system Link. Each feed shroud defines a proximal end 62 connected to its respective header 30 or branch pipe 32 and a distal end 64 remote therefrom, with the feed shroud 60 arranged to pass through its respective feed nozzle And the ammonia feed is directed down towards the air grid 14 into the interior of the acrylonitrile reactor. Meanwhile, the air grille 14 is in the form of a continuous metal plate 70 which is arranged below the feed distributor 16 and defines an upper surface 72, a lower surface 74, and a series extending between the upper surface 72 and the lower surface 74. An air hole 76 is used to guide the process air entering the ammonia oxidation reactor from below the continuous metal plate toward the feed distributor 16.

According to this feature of the invention, the distal end 64 of the feed shield 60 is arranged The distance from the upper surface 72 of the continuous metal plate 70 is 6 to 24 inches (~ 15 to ~ 61 cm). Preferably, the distal end 64 of the feed shield 60 is arranged at a distance of 8 to 12 inches (~ 20 to ~ 30.5 cm) from the upper surface 72 of the continuous metal plate 70. According to this feature of the present disclosure, it has been discovered that not only the poor reactor performance caused by insufficient reactant mixing can be largely eliminated by following this method, but also damage to the ammonia oxidation catalyst and caused by local reactor overheating Other problems can also be eliminated or at least substantially reduced by following this method.

From a theoretical / conceptual perspective, it seems beneficial to minimize The distance between the air grid 14 and the feed distributor 16 as this seems to help the maximum possible degree of mixing between the feed gas exiting the distributor 16 and the process air exiting the air grill 16 . However, in practice, it has been found that placing the air grid 14 too close to the feed distributor 16 helps to form reactor hot spots, as described above. When the distance between the air grid 14 and the feed distributor 16 is too small, some of the air holes 76 in the continuous metal plate 70 or the distal end 64 of the feed shroud 60 or both become located inherently stacked in the continuous Inside the catalyst / molybdenum scale stack on the upper surface 72 of the metal plate 70. This causes propylene, ammonia, and air reactants to contact each other inside these catalyst stacks, which behave similarly to fixed catalyst beds where heat transfer is poor and therefore the temperature rises rapidly. Accordingly, the distance between the air grid 14 and the feed distributor 16 measured between the distal end 64 of the feed shield 60 and the upper surface 72 of the continuous metal plate should be at least 6 inches (~ 15 cm) and Preferably at least about 8 inches (~ 20 cm) to avoid this problem.

Maximum distance between air grid 14 and feed distributor 16 In terms of distance, it has been found that at distances greater than about 24 inches (~ 61 cm), a portion of the catalyst in the reactor, particularly the portion between the air grid 14 and the feed distributor 16, is not effective Ground is used in the reaction. This reduces the conversion of propylene and ammonia reactants to the product acrylonitrile, which is clearly disadvantageous. Accordingly, the maximum distance between the air grille 14 and the feed distributor 16 measured between the distal end 64 of the feed shroud 60 and the upper surface 72 of the continuous metal plate 70 is maintained at no more than about 24 inches ( ~ 61cm), preferably no more than 18 inches (~ 45.7cm), no more than 14 inches (~ 35.5cm) on the other hand, and no more than 12 inches (~ 30.5cm) on the other hand to prevent this from happening Happening.

FIG. 6 illustrates a second feature of the technology of the present disclosure, in which The new support system, generally designated 80, is used to support the weight of the continuous metal plate 70 of the air grill 14, including the weight of any ammonia oxidation catalyst that can rest on the continuous metal plate. As shown in the figure, the support system 80 takes the form of a series of support beams 82 which are shown in certain embodiments as conventional I-beams. Each I-beam 82 includes an upper cross section 84 that defines an upper surface 86 on which a continuous metal plate 70 rests. Further, the underside of each upper cross section 84 defines a mating surface 88 for engagement with a support presser carried by the continuous metal plate 70 of the air grille 14 as discussed further below.

As further shown in FIG. 6, a series of support rods 90 are welded to the On the lower side of the continued metal plate 70, each end of the support rod defines a nose 92. As further shown in the figure, each protrusion 92 extends below the upper lateral section 84 of the corresponding I-beam 82, where the protrusion 92 engages the mating surface 88. With this structure, each support rod 90 functions as a press. For keeping the continuous metal plate 70 in contact with the upper surface 86 of the I-beam 82, thereby preventing the continuous metal plate from being lifted away from these tools by the force of the process air flowing upward through the air holes 76 in the metal plate Word beam.

As further shown in FIG. 6, at the end of each support rod 90 and Appropriate spaces 94 and 96 are arranged between the facing portions of the I-beam 82 for adapting to changes in the length of these support rods that inherently occur due to temperature changes experienced inside the reactor during startup and shutdown.

With this structure, the I-shape is engaged by the protruding portion 92 of the support rod 90 The corresponding mating surface 88 of the beam 82 firmly presses the continuous metal plate 70 against the upper surface 86 of the I-beam. It will be understood that other structures that provide similar means of attachment may be used in place of the support rod 90 and its associated protrusion 92. In any case, due to the spaces 94 and 96 arranged between the end of each support rod 90 and the facing portion of the I-beam 82 as a result of the significant temperature changes that occur inside the reactor 10 during startup and shutdown The changes in the length of the support rod 90 that occur occur easily through these spaces. Therefore, mechanical failure of the support system 80 is largely eliminated.

FIG. 7 illustrates a third feature of the technology of the present disclosure, in which A unique connection assembly is used for fixing the periphery of the continuous metal plate 70 of the air grill 14 to the side wall 12 of the reactor 10. As shown in the figure, the connection assembly, generally designated 100, includes a flexible plate 102 and a mating bulkhead 104. The flexible plate 102 includes an elongated metal sheet whose two ends are welded together so that the flexible plate 102 assumes a ring shape, particularly a cylindrical right section shape. With this shape, the flexible plate 102 is substantially consistent with the side wall 12 of the reactor 10 to which the air grill 14 is attached, because the middle portion of the reactor 10 is also formed into a cylindrical shape formula. Similarly, the partition 104 also includes an elongated metal sheet whose ends are welded together so that the partition 104 also assumes a ring shape.

As further shown in FIG. 7, the partition 104 is arranged on a flexible plate Between 102 and the side wall 12 of the reactor 10, the flexible plate 102 is defined by a lower portion 114 extending below the bottom portion 112 of the partition 104. Preferably, the bottom 110 of the flexible plate 102 extends about 6 to about 10 inches (about 15 to about 25 cm), more desirably about 7 to about 9 inches (about 18 to about 23 cm) below the bottom 112 of the partition 104. distance.

As further shown in FIG. 7, the bottom 110 of the flexible plate 102 is excellent. The periphery of the continuous metal plate 70 is optionally attached to the air grille 14 by welding. With this structure, a change in the diameter of the continuous metal plate 70 of the air grill 14 due to a significant change in temperature occurring inside the reactor 10 during start-up and shutdown is passed through the lower portion 114 of the flexible plate 102 (i.e. The portion of the flexible plate 102 that extends below the bottom 112 of the partition plate 104) flexes easily to accommodate it. Therefore, the mechanical failure of the joint connecting the periphery of the continuous metal plate 70 of the air grill 14 to the side wall 12 of the reactor 10 is largely eliminated.

Various aspects described in this article, shown in more specific maps 4-7 Aspects can be used in reactors with various sizes and diameters. In a preferred aspect, the reactor may have an outer diameter from about 5 to about 12 meters, on the other hand from about 8 to about 12 meters, and on the other hand from about 9 to about 11 meters. In another preferred embodiment, when a reactor outer diameter between about 8 to about 12 meters, or about 9 to about 11 meters is used, the air nozzle is capless and air is introduced vertically into the reactor, Most preferably it is directed vertically towards the feed shroud. In an alternative embodiment, when using a reaction between about 8 to about 12 meters, or about 9 to about 11 meters At the outer diameter of the reactor, the air nozzles in the air grille are covered, and the air is preferentially distributed horizontally into the reactor by the cover.

Although only a few implementations of the techniques of this disclosure are described herein Examples, but it should be understood that many modifications can be made without departing from the spirit and scope of the technology. All such modifications are intended to be included within the scope of the technology, which is limited only by the scope of the appended patent applications.

Claims (4)

An improved air grill system for use in a commercial oxidation or ammonia oxidation reactor, the improved air grill system includes a continuous metal plate that defines an upper surface, a lower surface, and a space between the upper surface and the upper surface. The continuous metal plate also defines a series of air holes for directing process air from below the continuous metal plate to above the continuous metal plate; and a support system for For supporting the weight of the continuous metal plate and any oxidation or ammonia oxidation catalyst that can rest on the continuous metal plate, wherein the support system includes a series of support beams and a fixedly attached to the continuous metal plate A series of support presses on the lower side, each support beam having an upper support surface that engages the lower side of the continuous metal plate, each support press is arranged to engage in a corresponding support beam defined thereon as follows The mating surface below the surface enables the support press to prevent the continuous metal plate from being lifted off the series of support beams. The improved air grill system according to claim 1, wherein the support beam is an I-beam with a corresponding upper cross section, and a lower surface of each upper cross section defines a mating surface, wherein, The continuous metal plate of the air grille system defines a lower surface, and further, wherein the support press includes a support rod attached to a lower surface of the continuous metal plate, the support rod having a defined protrusion The projection is arranged to engage a mating surface defined by an upper transverse section of the I-beam. A method for reducing movement in an air grid system in a commercial oxidation or ammonia oxidation reactor, the method comprising providing an air grid system, the air grid system comprising: a continuous metal plate defining an upper surface, A lower surface and a perimeter extending between the upper surface and the lower surface, the continuous metal plate also defines a series of air holes for directing process air from below the continuous metal plate to the continuous metal Above the plate; and a support system for supporting the weight of the continuous metal plate and any oxidation or ammonia oxidation catalyst that can rest on the continuous metal plate, wherein the support system includes a series of support beams and fixed A series of support presses attached to the lower side of the continuous metal plate, each support beam having an upper support surface that engages the lower side of the continuous metal plate, each support press being arranged in the following manner Engage a mating surface defined below its upper surface in a corresponding support beam, such that the support press prevents the continuous metal plate from being lifted off the series of support beams The method according to claim 3, wherein the support beam is an I-beam having a corresponding upper cross section, and a lower surface of each upper cross section defines a mating surface, wherein the air grille The continuous metal plate of the system defines a lower surface, and further wherein the support presser includes a support rod attached to the lower surface of the continuous metal plate, the support rod having an end defining a protrusion, the protrusion The portion is arranged to engage a mating surface defined by an upper transverse section of the I-beam.