EA005643B1 - A reaction apparatus for contacting reactants with a catalyst in a reaction zone while indirectly cooling the reactants by indirect heat exchange with a heat exchange fluid - Google Patents

Abstract

An apparatus is proposed for indirectly exchanging heat with narrow channels in a heat exchange type channel reaction zone uses plates (17) containing partially perforated sections (16) to simplify or eliminate the use of manifolds to distribute and collect different fluids to the various channels. The invention simplifies the operation by directly communicating adjacent channels across sections of perforations located at one end or the other of the channels. The arrangement of this invention provides the advantage of more compact heat exchanging reactor arrangements. The arrangement of the invention can also simplify the use of a single manifold arrangement at one end of the channels to facilitate catalyst unloading and catalyst replacement in the reaction channels.

Description

This invention relates mainly to the structures of plate heat exchangers, including the reaction zone and carrying out indirect heating of the reaction zone using a fluid coolant.

In many industries, such as the petrochemical and chemical industries, contacting reaction fluids with a catalyst in a reactor under suitable conditions for temperature and pressure results in a reaction between the components of one or more of the reactants in the fluids. When most of these reactions occur, heat release or absorption occurs to varying degrees, and therefore the reactions are exothermic or endothermic. Heating or cooling effects associated with exothermic or endothermic reactions can have a positive or negative effect on the functioning of the reaction zone. The negative impact may include, among other things: poor product formation, catalyst deactivation, production of undesirable by-products and, in extreme cases, damage to the reaction vessel and associated pipeline lines. Unwanted effects due to temperature changes will more often reduce the selectivity or product yield from the reaction zone.

The processes of exothermic reactions take place with the participation of a wide range of types of raw materials and products. Moderately exothermic processes include methanol synthesis, ammonia synthesis and the conversion of methanol to olefins. Production of phthalic anhydride as a result of oxidation of naphthalene or ortho-xylene, production of acrylonitrile from propane or propylene, synthesis of acrylic acid from acrolein, conversion of n-butane to maleic anhydride, production of acetic acid as a result of carbonylation of methanol, and conversion of methanol to formaldehyde are another class in general case of highly exothermic reactions. In particular, oxidation reactions are usually highly exothermic. The exothermic nature of these reactions has led to the fact that many systems designed to conduct these reactions, in their structure include equipment for cooling. Experts in the relevant field in practice are struggling with the release of exothermic heat, using structures with the use of hardening or heat transfer. Detailed theories describe in detail the methods of indirect heat exchange between the reaction zone and the cooling medium. The state of the art relies heavily on structures with tubular structures that contain the reaction medium and provide indirect contact with the cooling medium. The geometry of tubular reactors imposes restrictions on the design, in connection with which the use of large reactors and a very large surface of pipes is required to achieve high heat transfer efficiency.

Other methods of indirect heat transfer are carried out using thin plates that form channels. The channels alternately contain the catalyst and reagents in the same set of channels and the heat transfer fluid in the adjacent channels for indirect heating or cooling of the reagents and catalysts. The heat transfer plates in these indirect heat exchange reactors may be flat or curved, and they may have a modified surface, such as a corrugated surface, in order to increase heat transfer between heat transfer fluids and reagents and catalysts. Many methods of hydrocarbon conversion will work, mainly, while maintaining a temperature profile that is different from the one that will be created under the action of the heat of reaction. In many reactions, the most advantageous temperature profile will be obtained by maintaining essentially isothermal conditions. In some cases, the temperature profile, in the opposite direction to temperature changes associated with the heat of reaction, will provide the most favorable conditions. For these reasons, it is generally known to bring the reactants and the coolant medium into contact with each other in designs with cross-current, co-current or countercurrent. A specific channel arrangement for the heat transfer medium and reagents, which provides more complete temperature control, can be found in I8-A-5525311, the contents of which are included in this document by reference. Other plate designs suitable for indirect heat transfer are described in I8-A-5130106 and I8-A-540558b.

The separation of reagents from cooling or heating fluids at the inlets and outlets of the structures of plate heat exchangers makes it necessary to develop such structures and sophisticated manufacturing techniques. Many such structures increase the size of reactors, making it necessary to use manifolds and / or pipe systems to establish communication between adjacent channels. Simplifying the transfer of fluids between adjacent channels also leads to simplified distribution and collection of fluids at the inlets and outlets of plate heat exchangers. Improved designs for feeding reactants at intermediate positions along the flow path through the channels may also improve reactor performance.

The designs of channel reactors often contain catalyst particles. When the catalyst is deactivated, it becomes necessary to replace the catalyst. Complicated reservoir layouts for distributing and collecting flowable coolants and reagents can make the replacement of catalysts burdensome and time consuming.

- 1 005643

This invention provides sections of perforations in plates forming channels for indirect heat exchange between fluids in a plate reactor design. The perforation sections are located only on the part of the plates that form the channels, so that the fluid can communicate between adjacent channels while maintaining a significant length of channels through which reagents or heat-transfer fluids can pass through their way through the reactor. The portions of the perforations sections located at one end of the perforated plates for an individual fluid flow make possible any number of passes through the channels through the plate channel reactor. The requirements for pressure drop and heat transfer are the only practical limitation imposed on the number of passes through the channel reactor design of this invention, which can be made by any single fluid.

In suitable channel arrangements, heat exchange will occur directly through the total heat exchange surface. In designs, you can use an isolated coolant flow that provides heating or cooling for the channels for the reaction medium, or you can use a heat transfer fluid or a reagent from one channel as a reactant or heat transfer fluid in the adjacent channel. In particular, the feed stream or stream after passing the reaction out of the channels for the reaction medium can supply the fuel for combustion and generate heat locally in adjacent channels. It goes without saying that the channels for the coolant can also serve as channels for combustion, and they can receive fuel for combustion without communication with the fluid in the channels for the reaction medium.

In suitable designs, it is also possible to use different parts of common channels for different functions. Such functions include passing an intermediate fluid through adjacent channels to remove heat from the channel for the reaction medium in one place and supply heat back to the heated channels in the channel section located downstream. In other structures, the intermediate channels and the channel for the reaction medium can be laid in parallel between the heated channels in order to adjust the temperature in the channels for the reaction medium using the heated channels.

Accordingly, in the broad context, an embodiment of the present invention is an apparatus for carrying out reactions with introducing reagents into contact with a catalyst in a reaction zone with indirect heating or cooling of reagents in a reaction zone as a result of indirect heat exchange with a heat transfer fluid. The apparatus includes several plates spatially separated from each other, which form the first set of channels with a fluid inlet at one end and the second set of channels with a fluid outlet at one end. At least one perforation section provides fluid communication between the first and second multiple channels. At least part of the spatially separated plates has perforations at one of their ends, with each section of perforations located only on the part of the plate that has perforations.

In particular modifications of the invention, loading the catalyst into the channels for the reaction medium and adding the catalyst for additional exothermic or endothermic reactions may serve various technological purposes. For example, the short in length portion of the location of the catalyst load in the channels for the reaction medium may allow a free gap above or below the reaction zone to conduct additional preheating of the feedstock or cooling the resulting products. Again, the elongation of the heating channels may create additional surface area for heat exchange with open channels for products leaving the reaction zone or incoming reagents.

With respect to the catalyst, this invention has particular advantages. Simplification or elimination of collectors for the distribution and collection of coolants and reagents allows you to allocate the space required for unloading the catalyst. The apparatus will typically use a distribution manifold in the upper part of the apparatus for carrying out reactions that will distribute and collect the fluid from the fluid inlets and the fluid outlets in the upper part of the channels. The location of the collector in the upper part makes possible the formation in the lower parts of the channels of the outlets for particles and the inclusion of a device for unloading the catalyst. Thus, in the space below the channels there may be no collectors for the selection of the catalyst. The absence of any need for grids or other permeable surfaces in the lower part of the channels makes it possible to use a simple device for holding the catalyst, which will control the presence of the catalyst in the channels. The device will close the outlets for the particles in the catalyst hold position and open the outlets for the particles in the discharge position. Therefore, the channels may remain completely open for the selection of the catalyst when the doors or other suitable stop elements are removed from the bottom of the channels. As a result of the simplification of this design, it is also possible not to stop the flow of fluid through the channels when removing one stream and replacing the catalyst particles.

With regard to the flow of fluid, in the general case, the perforated section of the plate will determine the direction of flow of the fluid. For adjacent channels connected by perforated

- 2 005643 plate sections, there will always be a relative countercurrent flow between the channels. However, as a result of the separation of flowable coolants and reagents, direct-flow designs are also possible.

The plates forming the channels containing the reaction medium and the gaseous coolants can have any configuration that forms narrow channels. The preferred form of elements for heat transfer is a relatively flat plate, on which the corrugation relief is created. Shirring is used to maintain the distance between the plates, and, in addition, it also forms a support for the plates, providing a carrier system of narrow channels with good support organization. Additional details regarding the construction of such plate systems are given in υδ-Ά-5525311.

The invention is suitable for reactions with heat or for reactions with heat absorption. One process in which the construction of this invention can be used to advantage is the production of ethylene oxide. Particularly advantageous use of the present invention for the process is to obtain phthalic anhydride (PA) by oxidation of ortho-xylene. In the apparatus for carrying out the reaction, the initial flow of ortho-xylene is fed to a distribution manifold, which delivers a controlled amount of oxygen in a mixture with ortho-xylene. Bringing the mixture, in which the oxidation reaction will proceed, to the reservoir prevents the occurrence of explosive ratios between orthoxylene and oxygen. The lamellar structure of the heat exchange reactor quickly dissipates the large heat of reaction associated with the synthesis of PA. Improved temperature control allows you to improve the selectivity of the formation of products while the possibility of increasing productivity.

Another objective of this invention is to simplify the supply and extraction of reagents and fluid coolant from a heat exchange reactor in which a channel design is used, in order to make the design of channel reactors more compact and to simplify the integration of flow channels into a collector system.

Another objective of the present invention is to pass the reactants or the heat-transfer fluid through the design of the channel reactor with the organization of several passes while reducing the number of collectors.

The present invention is described in detail below with reference to the drawings, where FIG. 1 is a schematic illustration of the construction of a reactor of the present invention; FIG. 2 is a sectional view of FIG. 1, performed on line 2-2;

FIG. 3 is a cross-section of a perforated plate of the present invention;

FIG. 4 is a three-dimensional image of a section of a corrugated plate used in this invention;

FIG. 5 is a depiction of a single corrugated sheet having a perforation section;

FIG. 6 is a cross-sectional view schematically showing a reactor with a structure according to the invention;

FIG. 7 is a sectional view of FIG. 6, performed on line 7-7;

FIG. 8 is a cross-sectional view showing a schematic design for an alternative embodiment of the reactor of the present invention;

FIG. 9 is a sectional view of FIG. 8, performed on line 9-9;

FIG. 10 and 11 are diagrams showing the temperature profile and conversion parameters along the path length through tubes in a tubular structure when RA is obtained as a result of orthoxylene oxidation;

FIG. 12 to 17 are diagrams showing the temperature profile and conversion parameters along the path length through channels in the construction of plate-type reactors with heat exchange to obtain RA as a result of orthoxylene oxidation.

This invention may be suitable in any endothermic or exothermic process in which the reactant or part of the reactant is a heat source for heating the mixture for an endothermic reaction or heat sink for cooling the mixture for an exothermic reaction in the structure formed by the elements of the plate heat exchanger. Additional requirements that determine the compatibility of any process with the design of a plate heat exchanger are usually relatively low temperature differences (DT) and pressure differences (DS) between any heat exchange zone and the reaction zone. Temperature differences of 200 ° C or less are preferred for this invention. The pressure differences will remain low, and they will usually meet the requirements for pressure drop as it passes through the catalyst bed. The pressure difference when passing through the plate elements in the transverse direction will usually not exceed 0.5 MPa.

At least the channels for the reaction medium will usually contain a catalyst that stimulates the reaction. Suitable catalysts for the previously mentioned processes, as well as for other technological processes, are well known to those skilled in the art. The particulate catalyst can fill the channels for the reaction medium in accordance with the

- 3 005643 is necessary for the reaction time and for any preheating, which precedes the reaction, or subsequent cooling in the channels for the reaction medium. As an alternative to the particulate catalyst, the catalyst can also be applied as a coating on the surface of the plates in various reforming zones. In particular, it may be advantageous to apply a coating in the form of a reaction catalyst onto the plates to obtain an upper section containing the catalyst and a lower section containing no catalyst, which is in heat exchange with the secondary catalytic zone through the plates forming the channels.

The heat transfer fluid used in the method or apparatus of this invention may be of any type of fluid that can provide the necessary cooling or heating capacity. The requirements for heating or cooling can satisfy a wide range of fluid coolants. Such fluids will include process flows that are integral to the process, as well as auxiliary fluids. Fluid can absorb or release heat due to changes in its heat content due to latent heat of phase transition or heat of reaction. For highly exothermic processes, molten salts or metals can be particularly useful as a heat exchange medium.

For those cases where it is appropriate to ensure compliance with the heat balance requirements for a particular reaction, specialists in the relevant field have information about specific catalysts that stimulate additional exothermic and endothermic reactions. Such catalysts can advantageously be placed in the channels for the coolant to provide cooling due to the heat of reaction, as well as cooling through the use of heat content or latent heat of phase transition of the reactants. An example of such a combination of endothermic and exothermic catalysts is the autothermal reforming of light hydrocarbons, usually methane, to produce what is generally called "synthesis gas". Synthesis gas essentially consists of hydrogen and carbon monoxide, lesser amounts of carbon dioxide that have not undergone the conversion of hydrocarbons and other components, which may include nitrogen and other inert components. A stable endothermic reforming reaction is effectively balanced by a stably exothermic oxidation reaction, which can be caused by partial catalytic or thermal oxidation of hydrocarbons. Varying hydrocarbon moles, either in a reforming reaction or in an oxidation reaction, is used to balance the heat of heat released and the heat absorbed.

This design is particularly suitable for the inclusion in the design of channels with multiple passages, in which only two pairs of adjacent channels are connected and in which a channel for an exothermic reaction is located between alternating channels for heating and channels for an endothermic reaction. In the configuration, which is a three-pass construction, the relatively cold reactants flow into the heating ducts, where, as a result of indirect heat exchange with the channels for the reaction medium, the corresponding heating and cooling occur. Flow after the reaction from the channels for the exothermic reaction to the channels for the endothermic reaction provides additional cooling channels for the reaction medium through the common plates, which form channels for the endothermic reaction, as well as adjacent channels for the exothermic reaction.

FIG. 1 and 2 illustrate the basic design of the reactor for the present invention. In this construction, the reactor 11 contains one group of pairs of channels 12. Non-perforated plates 19 divide the pairs of channels for heat carrier into channels with a downward flow 15 and into channels with an upward flow 18. The collector 13 supplies the incoming fluid to the inputs of the 14 channels with a downward flow 15. Perforated sections 16, made in the lower part of the perforated plates 17, produce a flow of fluid into the channels with the upward flow 18.

The collector 13 comprises inlet chambers 20 and outlet chambers 21, as shown in FIG. 2. The separator plates 22 separate the volumes of the inlet chamber 20 and the outlet chamber 21. As shown by the symbol ®, the incoming fluids flow from line 23 along the inlet chamber 20 to the inlets 14 to the channels 15. The overlapped sections 24 of the upflow channel 18 prevent the fluid from flowing transported by the inlet chamber 20 into the channels with the ascending flow 18. Similarly, the discharge chambers 21 collect the fluid from the channels with the ascending flow 18, as shown by the □ symbols, for entrainment by the flows at the outlet 25 while blocked section 26 to prevent leakage of fluid from the channel 15 into the outlet chamber 21.

Channels 15 and 18 can perform several different functions. Channels 15 can provide cooling as a result of preheating the reagents for the endothermic reaction that occurs in the channels 18. Conversely, the channels 15 can receive a heated stream of reagents, which will provide additional heat for the endothermic reaction that occurs in the channels 18. Alternatively, the channels 15 may contain an oxidation catalyst for heating the reactants that enter the channels 18, under the action of combustion.

The channels of this invention are in particular suitable for use with a particulate catalyst. FIG. 1 shows a single catalyst loading design for exothermic

- 4 005643 reactions. The cold feed reagents flow through line 23 and pass down to channels 15. When the incoming reagents pass through the top of channels 15, the top of channels 18 serves as a heat exchange zone for preheating the incoming feedstock with outgoing reagents. The exiting reactants were heated by the exothermic reaction that occurs in the lower part of the channels 18. When the reactants pass into the lower part of the channels 15, they are subjected to additional heating in a position directly opposite the exothermic reaction zone that occurs in the lower parts of the channel 18. When the heated reactants pass through perforated section 16 in the lower part of the perforated plate 17, they pass to the catalyst particles 27, which partially fill the lower parts of the channels 18. The perforations in part 16 have that Kie sizes that prevent the passage of catalyst particles from the channels 18 into the channels 15 while simultaneously passing a stream of reagent fluids from the channels 15 to the channels 18.

The design of FIG. 1, in particular, is suitable for replacing the catalyst in the channels 15, 18, or both. In the specific construction shown in FIG. 1, catalyst 27 is only in channels 18, which are used for the exothermic reaction. As soon as catalyst 27 is deactivated or its replacement is required, a catalyst unloading device, shown in general terms as 28, will allow catalyst unloading from channels 18. The minimum unloading device can consist of one set of doors 29, which, at least, overlapping the lower parts 30 of the channels 18, preventing the catalyst from falling out of the channels when the doors 29 are in the closed position — shown by solid lines. Moving the doors 29 to the opening position — shown by dashed lines — results in the opening of the lower portions 30 of the channels 18 for discharging the catalyst particles.

The unloading device 28 may further include a secondary set of doors for selectively holding and unloading the catalyst from the channels 15. The second set of doors 31 is shown in the opening position for unloading the catalyst. The secondary doors 31 have slots 32 dividing the locking strips 33. When the door 31 is folded up to the lower portions 34 of the channels 15, the locking strips 33 overlap the lower portions 34 of the channels 15, preventing any catalyst unloading. The slits 32 allow the catalyst in the channels 18 to flow past the secondary doors 31 to achieve full unloading before unloading the catalyst from the channels 15 by moving the doors 31 to the opening position shown in FIG. 1. Once the catalyst has completely left the channels 18, the opening of the doors 31 will make it possible for the catalyst to flow out of the channels 18 without any mixing of the particles of the various catalysts.

The catalyst is easily loaded into the channels 18 and optionally into the channels 15 from the upper part of the reactor 11. To load the catalyst from the upper part of the channels, you can remove the collector 13 in order to gain access to the open sections of the channels and the inlet and exhaust chambers 20 and 21, respectively. When using the catalyst only in the channels 18, the inlet openings 14 of the channels 15 can be blocked off with fixed grids in order to prevent particles from flowing over here. If the catalyst loading is carried out in both channels, you can turn on the corresponding plate with slots and place it over the upper parts of channels 15 and 18 in order to selectively close the channels that do not accept the catalyst during a particular cycle during the loading operation.

It is also possible to move the catalyst by circulating the reactants or coolant through the reactor 11. The inlet and outlet chambers 20 and 21 can form for the dispersion of the catalyst distribution space along the upper parts of the channels that remain open in each specific chamber. In this design, the chamber or series of chambers can replace the doors 29 and 31 to form an unloading device formed by collecting chambers for receiving material in the form of particles. Suitable collection chambers may have a structure similar to that shown in FIG. 2 to collect the catalyst from selected channels. Adjustable selection and addition of catalyst from the upper and lower parts of the reactor 11 can provide any desired level of catalyst in the reactor.

The invention is based on relatively narrow channels, allowing to achieve effective heat exchange through thin plates. In general, the channel width should be less than one inch on average, with an average width of less than 1/2 inch preferred. Plates suitable for this invention will include any plates that will make a high heat transfer coefficient possible. Thin plates are preferred, which typically have a thickness in the range of 1 to 2 mm. Plates usually consist of ferrous or non-ferrous alloys, such as stainless steel. Alloys preferred for the plates will withstand extreme temperatures, and they will feature high levels of nickel and chromium. Plates can be made in the form of curves or in the form of other configurations, but in the general case, flat plates are preferred for stacking purposes. Flat plates may have channels formed by machine processing, chemical pickling, or other methods. Again, each plate can be smooth, and additional elements, such as spacers or jumpers with punched holes, can form turbulence for the fluid in the channels.

Each plate preferably has a corrugation in which the corrugations are inclined with respect to the flow of reagents and the heat-transfer fluid. The presence of corrugation is the cause

- 5 005643 variable channel width, determined by the height of the corrugations. In the case of corrugation, the most practical way to determine the average channel width is to divide the volume of the channels by the cross-sectional area parallel to the main plane of the plates. With this definition, corrugated plates, with substantially straight, sloping side walls, will give an average width that is equal to half the maximum width across the channels.

FIG. 3 shows the preferred corrugation structure for the plates 17, which separate the channels 15 and the channels 18. The corrugation pattern can perform at least two functions. One function is to create a structural support for adjacent plates. Another function is to stimulate the occurrence of turbulence to improve the efficiency of heat transfer in a narrow channel for the reaction medium. FIG. 3 shows corrugations formed by ridges 37 and valleys 38. The frequency or pitch of the corrugations may vary as desired in order to stimulate the occurrence of turbulence in any variable degree. Therefore, corrugations smaller with respect to the direction of flow of the fluid flow, shown with ridges 37 and valleys 38, will create less turbulence, while a more significant step of the flutes with respect to the direction of flow of the fluid fluxes with ridges 39 and valleys 40 will create increased turbulence where it is needed. The corrugation pitch and frequency can also vary within an individual coolant channel in order to vary the heat transfer coefficient in different parts of the channel. The channels may preferably have a flat section 41 around their contour to facilitate the closure of the channels along their side and top parts where necessary. Except for the perforation, the plates 19 are essentially the same as the plates 17, they preferably contain corrugations, and they may vary the step of the corrugations to change the turbulence and flow coefficients for heat exchange and other purposes as desired.

The perforation section 16 is located across the plate 17. The perforations 42 usually have a relatively small diameter that allows fluid to flow through the perforated section, but does not allow migration through the perforated section of the catalyst. The perforations will typically vary in size from approximately 1.5 mm to approximately 10 mm. The perforation section 16 may be located in the intermediate region of the plate to create a bypass for the fluid in applications for specific technological processes, but usually its position is one end of the plates. The location of the corrugation at one end of the plates allows you to maximize the path of fluid flow through the channels. The flow region created by the perforated section will usually at least be equal to the resulting flow region along the flow path in the channel. If one of the channels contains particulate catalyst material, then the resulting flow region will consist of the average living cross-section between the catalyst particles in the cross section of the channels 18. In most cases, the perforations will take up less than half the channel length, and usually less than 25% of the channel length. Preferably, the perforated section of the channel will occupy no more than 10% of its length in order to maximize the flow path of the fluid along the channel.

FIG. 4 shows a typical cross section for a structure with corrugated plates, where the corrugations on the plate 44 extend in the opposite direction to the corrugations of the plate 46, thus forming alternating channels 47 and 48. The holes 49 form perforations of the present invention in the plates 44. FIG. 4 illustrates the preferred corrugated plate structure, where the herringbone pattern on the surfaces of the opposite corrugated plates is oriented in opposite directions, and the surfaces of the opposing plates are in contact with each other, forming flow channels and forming a structural support for the plate sections. FIG. 5 further illustrates another possible plate configuration.

In order to implement this invention in practice, it is not necessary that each channel for the reaction medium alternate with the channel for the coolant. In possible configurations of the section for the reaction medium, two or more channels for the coolant may be located between the channels for the reaction medium in order to reduce the pressure drop on the side of the medium for heat exchange. Designs with dual channels can define a perforated plate that separates adjacent channels for coolant and which has perforations along its entire surface. The use of a package of perforated plates can improve the heat transfer in relation to the channels for the reaction medium while ensuring good circulation over the entire cross section of the heated channel.

FIG. 6 and 7 demonstrate a design in which different fluids circulate in two independent groups of channel pairs without falling on opposite ends of the reactor 50 structure. Fluid at the inlet 51 flows into the structure of the collector 52, having upper inlet chambers 53 and upper outlet chambers 54. The inlet chamber 53 distributes the upper stream at inlet 51 through pairs of channels 55, indicated by the symbol ®. The top stream at outlet 56 collects fluid from the first group of pairs of channels 55 through the upper outlet chambers 54 in the openings of the channels, indicated by the symbol Θ. The perforated section 57 connects the two channels in the first group of pairs of channels 55. Similarly, the bottom stream at the inlet 58 is distributed over the second group of channel pairs 59 using

- 6 005643 collector structure 60. The upper perforated section 61 in the second group of channel pairs 59 organizes communication between the channels to select the bottom stream at outlet 62 through the collector 60.

With this design, two different fluids can circulate in reaction with heat exchange in full interaction of intersecting flows using simple designs of collectors at opposite ends of the reactor design. In the same way, the first group of channel pairs can define channels for the coolant for circulating the heat-transfer fluid, and the second group of channel pairs can define channels for the reaction medium for receiving a stream of reagents and issuing a stream after passing through the reaction.

FIG. 8 and 9 demonstrate the design of the channels for the reaction medium, which uses an odd number of passes, which allows you to have a simplified design of the inlet and exhaust manifolds. FIG. 8, inlet flow 65 enters an intake manifold 66 having a single chamber. Fluid entering the inlet manifold 66 flows down into the inlet channels 68 in a sequence formed by three-passage channel designs 67. The perforated sections 78 in the lower part of the plate 69 pass the fluid from the inlet channel 68 into the middle channel 70 and the upper perforated section 74 continues the transfer of fluid from the middle channel 70 to the exhaust channel 71. The collector 72, again containing one open chamber, collects the stream of reaction products from the exhaust channel 71 for selection as an outlet stream 73. Thus, in the construction of FIG. 8, the perforated sections are arranged alternately at opposite ends of the plates, forming channels defining the flow path in which the flow of fluid occurs at one end of the channels and the collection of fluid occurs from the opposite end of the channels.

FIG. 9 shows a further modification of the construction of FIG. 8, where side collectors 75 are located in the gap between several batteries of 76 channels for heat carrier. With the help of the reservoir structures described in FIG. From 6 to 8, individual fluids or several fluids can be fed into the coolant channels. Side channel 75 may dispense or collect fluid from the sides 77 of one or more channels formed by separated plates. For purposes of illustration in FIG. 8 and 9, openings 79 are shown in the side portions of the channels 70 for supplying intermediate stream 80. The openings 79 may be located along the entire length of the channel that communicates with the side headers, or only on the part, as shown in FIG. 8 holes 79 '. From the point of view of manufacturing the structure in practice, it would be more convenient to create holes in the side sections of the channels by intermittent seam welding on the side sections of the channels, rather than as a result of making the through holes.

Examples

The following examples present the operation of the tubular reactor as a base case and the design of a channel reactor design of a type that uses two independent flow paths shown in FIG. 6 and 7. All examples demonstrate the oxidation of ortho-xylene to phthalic anhydride. Numerical data use well-defined kinetic data and experimentally obtained heat transfer data. All data on catalysis were based on the performance parameters for vanadium pentoxide deposited on the surface of the material based on silicon carbide, with a specific surface area of 2000 cm ² / g. In all examples, it was done in such a way that the phthalide content in the reaction product stream was kept at a level of less than 1000 ppm in the RA product. Examples are also models of using molten salt as a cooling medium.

Example 1

The example defines the operational characteristics of a tubular reactor as a base case, and it produces results similar to the operational characteristics of modern industrial tubular reactors. In this base case, the feedstock in the form of air containing an orthoxylene concentration of 75 g / nm ³ is passed through a tube three meters long and 25 mm in diameter at a mass flow rate of 10,000 kg / m ² / h, which creates a pressure drop of 0.3 bar along the tube . The tubular reactor model uses a particle in the form of a ring with an outer diameter of 9 mm, usually perforated with a diameter of 5 mm. The circulation of the contents of the salt bath at 698 ° K on the side of the shell of the tubes provides cooling. The feedstock enters the tubular reactor at a temperature of approximately 700 ° K. The final phthalide content in the product RA was below 1000 ppm. FIG. 10 graphically depicts the temperature profile along the length of the representative tube. The tube reaches a peak temperature of approximately 835 ° K, within the first 50 cm of the path in it. FIG. 11 illustrates the substantially complete conversion of ortho-xylene to approximately the first 100 cm of tube length. FIG. 11 also represents the fact that going to the limit, the conversion in the tubes leads to a decrease in the concentration of orthotolualdehyde and phthalide to levels less than 1000 ppm, with an increase in the selectivity for RA to approximately 83%.

Example 2

The reactor, related to the type of plate heat exchanger, operates at the same orthoxylene inlet concentration and mass flow rate through the channels for the coolant as the tubular reactor. The design of the channels is such that in the gap of 6 mm between the channels in one of the channel pairs with

- 7 005643 holding a spherical catalyst with a diameter of 2 mm. In order to maintain the same 0.3 bar pressure drop as the channels pass as the tubes pass, the flow in the process for the plate reactor structure is reduced to 7500 kg / m ² / h. However, as a result of a change in the size of the reactor, relating to the type of plate heat exchanger, the same ratio of heat transfer surface area to specific surface area of the catalyst per reactor volume is maintained as in the tubular reactor design. With the same concentration of orthoxylene in the supplied air of 75 g / nm ^{3, the} process temperature at the reactor inlet, related to the plate heat exchanger type, is increased by 15 ° K compared to the case of the tubular reactor, in other words, to a temperature of approximately 713 ° K in order to sustain the same level of phthalide in the product RA. Even with increasing inlet temperature, FIG. 12 shows that the peak temperature in the channels decreases to approximately 815 ° K, which represents a drop in temperature of approximately 20 ° K compared to the case of a tubular reactor. Again, FIG. 13 shows a fast conversion of ortho-xylene along the path length in a plate heat exchanger type reactor with approximately the same RA selectivity and orthotolualdehyde and phthalide levels less than 1000 ppm. Thus, a decrease in temperature in this example shows that the reactor, which is of the type of plate heat exchanger, has approximately 30% more capacity for total heat transfer compared to a tubular reactor.

Example 3

Example 3 assesses the magnitude of the increase in the concentration of orthoxylene in the air supplied to the reactor, relating to the type of plate heat exchanger, in the range from 75 to 110 g / nm ³ in order to determine the concentration that results in the same peak temperature in the reactor, relating to the type of plate heat exchanger, as in the tubular reactor. Heat from the additional oxidation of ortho-xylene requires an increase in the temperature of the circulating salt from 713 ° K in Example 2 to about 717 ° K in order to withstand the concentration of phthalide in the RA product at less than 1000 ppm. At a concentration of approximately 105 g / nm ³ , the peak temperature in the plate reactor (see FIG. 14) approaches the maximum temperatures for the tubular reactor design. As established in FIG. 15, the maximum concentration of orthoxylene can be significantly increased compared with the case of a tubular reactor as a result of using a plate heat exchanger while maintaining, however, the RA selectivity of approximately 83% (mol).

Example 4

Example 4 demonstrates the effect on temperature and on conversion of breaking the supply of orthoxylene at the stage with additional feeding at the intermediate point in the channels in such a way as to restore the maximum concentration of 75 g / Nm ³ . As a result of the breaking of the supply of raw materials at the stage, the side distribution channels of FIG. 8 and 9 in combination with one of the groups of channel pairs shown in FIG. 6 and 7. In this example, reduce the initial flow of feedstock in such a way as to reduce the value of the process stream at the inlet to the plate reactor to 5525 kg / m ² / h for the first stage of the supply of orthoxylene. In this construction, the supply of an additional amount of ortho-xylene is carried out 30 cm further along the path length in a reactor with a heat exchanger in the middle section of one of the channels in each pair of channel groups with ascending and descending flows. With less process flow, the temperature of the circulating salt bath is reduced to 700 ° K, which is equivalent to the temperature at the inlet to the tubular reactor. The path length for the channels in this example increases to a total of 130 cm, which creates an additional 30 cm for the first stage, while maintaining the same 100 cm for the second stage as used in examples 2 and 3. The additional length reduces the content phthalides in the product PA to less than 1000 ppm. Nevertheless, even with an increased length, the total pressure drop remains below 0.3 bar from the example with the tubular reactor. FIG. 15 represents the maximum peak temperature in the first stage is less than 810 ° K. FIG. 16 shows substantially complete conversion of ortho-xylene within the first 30 cm from the feed point. FIG. 17 shows RA exposure to a limit greater than 83%. As a result, a process unit using a tubular type reactor to produce 50 thousand metric tons of RA per year will require the use of 33 cubic meters of catalyst. Compared to the fact that a reactor with a plate heat exchanger, using multiple feeds of the feedstock to produce the same amount of product RA, would require the use of only approximately 12.8 m ^{2 of} catalyst, which thus significantly reduces the capital costs required for the plate construction. reactor compared with the tubular reactor design. If you look at it from the other side, this example in the case of a step-by-step input of feedstock demonstrates an effective doubling of the concentration of orthoxylene in the feedstock in comparison with the concentration in the tubular reactor.

In general, the examples reveal many technological advantages for the design of a plate reactor in comparison with the design of a tubular reactor. Comparison of examples demonstrates the overall increased thermal efficiency in the case of using the design of the reaction

- 8 005643 torus with a plate heat exchanger, in which to obtain phthalic anhydride enter the mixture of air and orthoxylene at one point of entry. The use of a plate reactor design with an increased concentration of orthoxylene in the air at one inlet for the feedstock allows for additional advantages. Moreover, the stepwise feeding of the ortho-xylene feedstock into the plate reactor design significantly reduces the costs required for the plate reactor design. Such savings may include a 50% reduction in air compression costs and a significant reduction in capital costs due to the smaller relative size of the plate reactor compared to a tubular reactor.

Claims (6)

CLAIM 1. Apparatus for carrying out reactions for bringing the reactants into contact with the catalyst during indirect heating or cooling of the reactants in the reaction zone under the influence of indirect heat exchange with a fluid coolant, including many stacked plates (17, 19) that form the first set of channels (15) with a fluid inlet (14) at one end and a second plurality of channels (18) with a fluid outlet, wherein any of said plurality of channels — the first or second — is configured to charge channels with a catalyst, a plurality of stacked into a stack of plates (17, 19), including non-perforated plates (19) to prevent fluid from flowing between adjacent channels with perforated plates (17), alternating with non-perforated plates to determine a continuous flow path from the fluid inlet (14) to the outlet fluid, and at least one section of perforations (16) to create a message for the fluid between the first and second sets of channels (15, 18), where at least a portion of the stacked plates has perforations at one of its ends, while h of each section of perforations (16) located on only a portion of the plate (17) which has perforations, and at least one set of perforations is located opposite the entrance of the fluid (14). 2. The apparatus according to claim 1, in which in the distribution manifold (20, 21) for distributing the fluid at the inlets for the fluid (14) and collecting it from the outlets for the fluid in the upper part of the channels (15, 18) at least part of the channels has exits for particles (30) in its lower parts, through the inlets for the fluid (14) of the first set of channels (15) and / or the exits for the fluid of the second set of channels (18), where particles are received, and in the device for discharging the catalyst (28), the outputs for the particles (30) are closed in the holding position of the catalyst and open s for particles in the unloading position. 3. The apparatus according to claim 1, in which each second plate (17) in a plurality of plates (17) has a perforation section (16) in its lower part to create a direct message for the fluid flow between the lower parts of the first and second set of channels (15 , 18), and the input for the current medium (14) and the output for the fluid are at the same end of the first and second set of channels (15, 18). 4. The apparatus according to claim 2, in which the first and second plurality of channels (15, 18) have exits for particles (30) in their lower parts, and the device for unloading (28) includes a first door (29) that opens one of sets of channels for unloading particles in the first position and holds the particles in the channels in the second position, while the device for unloading includes a second door (31) having a plate configuration with slots and located on top of the first door when the second door holds particles in one set of channels. 5. The apparatus according to claim 1, in which at least two perforated plates (69) are located between the non-perforated plates, and on adjacent perforated plates, the perforation sections are located at opposite ends to determine the continuous flow of the stream, which passes at least three channel lengths ( 68, 70, 71), and the first manifold (66) distributes the fluid to the fluid inlets, and the second manifold (72) collects the fluid from the opposite end of the channels. 6. An apparatus for carrying out reactions for bringing the reactants into contact with the catalyst during indirect heating or cooling of the reactants in the reaction zone under the influence of indirect heat exchange with a fluid coolant, including a plurality of plates separated from each other (69) forming the first set of channels (68, 70, 71) with a fluid inlet at one end and a second plurality of channels (68, 70, 71) with a fluid outlet at one end, any of said plurality of channels — first or second — is configured to allow loading of a channel in the catalyst, at least one section of perforations (74, 78) to create a message for the fluid between the channels, where at least a portion of the plates separated from each other has perforations at one of its ends, while each section of perforations is located only on the part of the plate that has perforations, and - 9 005643 a lateral manifold (75) extending along the lateral sides of the channels, and lateral sides of a portion of the channels having openings (79 ') for creating a communication with the lateral manifold for distributing fluid from the side manifold or for collecting fluid into the side manifold.