EP2089148A1

EP2089148A1 - Process and apparatus for injecting oxygen into a reaction gas flowing through a synthesis reactor

Info

Publication number: EP2089148A1
Application number: EP07819574A
Authority: EP
Inventors: Max Heinritz-Adrian; Stefan Hamel; Lothar Semrau
Original assignee: Uhde GmbH
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 2006-11-16
Filing date: 2007-11-05
Publication date: 2009-08-19
Also published as: RU2417833C2; WO2008058646A1; RU2009122697A; DE102006054415A1; US20100137670A1; NO20092245L; JP2010510046A

Abstract

Synthesis reactor comprising an apparatus for injecting oxygen, which can be initially charged in pure form, as air, or mixed with inert gas or water vapor, into a reaction gas which can flow through the synthesis reactor which finds use, for example, in an oxydehydrogenation plant, wherein oxygen and reaction gas have different temperatures, wherein a distributor element is provided upstream of the device for accommodating a catalyst charge in flow direction of the reaction gas, said distributor element comprising a distributor body, two tube plates and a multitude of gas guide tubes for passing the reaction gas through, and the oxygen can be supplied to the chamber between the gas guide tubes, wherein at least one baffle plate is arranged orthogonally to the gas guide tubes and divides the intermediate space into at least two distributor chambers, wherein the distributor chambers are connected to one another or merge into one another fluidically through one or more orifices, at least one gas line leads into the first distributor space in flow direction, through which the oxygen can be supplied, and the lower tube plate is provided in flow direction with a multitude of orifices in the form of nozzles, bores or the like, through which the oxygen can leave the intermediate space, wherein a solids-free gas mixing zone is provided below the lower tube plate.

Description

Method and device for injecting oxygen into a reaction gas flowing through a synthesis reactor

[0001] The invention relates to a synthesis reactor comprising a device for introducing oxygen-containing gas into a reaction gas which flows through the synthesis reactor, wherein the oxygen-containing gas to be charged and the reaction gas have a different temperature, wherein in the flow direction of the reaction gas before the device a Sauerstoffverteilele- ment from a manifold body with two tube plates and a plurality of gas guide tubes for the passage of the reaction gas is provided for receiving a catalyst filling and the oxygen to the space around and between the gas guide tubes can be fed. In this case, at least one baffle is arranged orthogonally to the gas guide tubes, which divides the intermediate space into at least two distribution spaces, wherein the distribution spaces are fluidly interconnected by one or more openings or merge into one another. Furthermore, a gas line into the first distribution chamber, via which the oxygen is supplied, and the downstream in the flow direction tube bottom is provided with a plurality of openings in the form of nozzles, bores or the like, through which the oxygen can leave the gap and into a below the bottom tube bottom provided solids-free gas mixing zone can be passed. In this case, the supply of the oxygen-containing gas and the reaction gas in the mixing zone according to the invention is carried out such that mixing is achieved before the gas mixture enters the catalyst filling, where then run the desired reactions. For this purpose, the distance between the nozzle end and the surface of the catalyst layer is ideally chosen so that mixing has taken place, but the reactions in the mixing chamber have not yet taken place or have only taken place to a negligible extent.

Gas distribution systems for synthesis reactors are widely described in the prior art. US 6,267,912 B1 discloses a synthesis reactor with a distribution system in which each channel carrying reaction gas is connected to one or more channels in which the feed gas flows. The proposed distribution system is structurally very complicated and there is the problem of selecting the channel cross sections so that the required partial flows of the reaction gas and the feed gas are set exactly.

Systems are also known in which the reaction gas flows through a plurality of gas guide tubes and the feed gas in a distribution space this Surrounds the gas guide tubes and enters through one or more holes directly into these gas guide tubes and mixed there. Synthetic reactors with such a gas distributor device are described in US Pat. No. 5,106,590 A, DE 38 75 305 T2 or WO 02/078837 A1. In this device, the problem remains that even with slightly different opening cross sections, manufacturing inaccuracies or pressure differences in the gas guide tubes they are supplied differently with feed gas. Since no cross-mixing takes place in front of the catalyst bed, this gas stream passes through the catalyst bed, so that the conversion decreases. DE 10 2004 024 957 A1 shows a similar distributor device, which is placed on the catalyst bed or is adjacent. Here there is the problem that the hot gas jet entering the catalyst burns holes in the bed in a non-optimal arrangement.

WO 03/004405 A1 and JP 2003-013072 A describe a method and an apparatus for producing a synthesis gas by means of autothermal reforming (ATR). In this case, an oxygen-containing gas is mixed with a reaction gas such that it partially oxidizes before the gas mixture passes into a subsequent catalyst bed. The distributor device is designed so that the oxygen-containing gas is passed over the inner part of a nozzle and the reaction gas is supplied via an outer concentric annular gap, wherein the design is such that forms a stable as possible diffusion flame. Within the distributor, a perforated plate is further provided, with which an artificial pressure loss is generated, which is intended to ensure that the reaction gas is quantitatively distributed as uniformly as possible to the concentric annular gaps. The device proposed there is therefore not the reaction-free, pure mixing to the target, but represents an overall burner device that performs the partial oxidation of numerous individual burner in stable flames.

In contrast to the present invention, which allows ideally only a mixing, but no or only a very small reaction conversion before the gas mixture enters the catalyst layer, in WO 03/004405 A1 and JP 2003- 013072 A, the targeted partial Oxidation of the reaction gas brought about so that forms a stable flame as possible to the coaxial nozzles. Moreover, in WO 03/004405 A1 and JP 2003-013072 A, inversely to the present device, the reaction gas within the distributor device and the oxygen-containing gas are passed through the axial tubes to the burners. This results in a large, oxygen-filled volume lying in the flow direction in front of the distributor device. In the present invention, oxygen-containing gas is only within the limited volume of the oxygen distribution device, not least for safety reasons Considerations is preferable.

In WO 2007/045457 a mixing device is presented, the oxygen and reaction gas mixed by oxygen is passed through axial tubes and distributed over a respectively located at the end of the axial tubes distributor device in the radial and axial directions in the reaction gas. The axial tubes protrude beyond the bottom plate into the mixing zone. The reaction gas is conducted outside the axial tubes and fed via slots or openings of the mixing zone.

Investigations have shown that beyond the tube plate extended tubes form zones with unfavorable flow conditions and recirculations in particular between the plate and the end of the tubes. As a result, both the mixing is impaired and the residence time of a portion of the gas mixture or the individual gases extended so that local reactions can proceed to a greater extent. For this reason, in the present invention, the axial tubes are flush with the lower tube sheet and connected as a measure for injection of the specified nozzles with the geometrical arrangement characteristics of the axial tubes and the spatial arrangement of the catalyst bed, because only so a mixing in the desired Form can be performed.

Furthermore, WO 2007/045457 does not provide deflection or guide plates within the distributor device. As a result, in the case of different temperatures of both gases, a temperature distribution in the gas will inevitably also be established within the distributor device before it reaches the mixing chamber. As a result, both the uniform distribution of the mass flow over the intended outlet slits is impaired, and the mixing after exiting into the mixing chamber will be uneven due to the locally different temperatures and the different substance values over the reactor cross section. In contrast, the present invention provides a targeted

Flow guidance and residence time within the oxygen distribution box by means of baffles, whereby a uniform temperature of the oxygen is achieved before it is passed through the nozzles in the mixing chamber. The uniformity of the temperature within the box before exiting the nozzles is a prerequisite to ensure a uniform flow over the entire reactor cross-section of the nozzle and thus uniform supply into the mixing chamber. The device makes it possible to set a uniform oxygen temperature even at high temperature differences of reaction gas and oxygen and large reactor cross-sections and thus large dimensions of the oxygen distribution device. There is therefore still the task of providing a synthesis reactor, which is structurally simple and allows safe process management.

The object is achieved by the synthesis reactor according to the invention with a device for the injection of oxygen, wherein the oxygen in pure form, as air, or mixed with inert gas or water vapor can be presented. This oxygen-containing gas can be introduced into a reaction gas which flows through a synthesis reactor, which is used, for example, in an oxydehydrogenation plant, the oxygen-containing gas and the reaction gas having different temperatures, an oxygen distribution element being provided in the flow direction of the reaction gas upstream of the device for receiving the catalyst charge is provided from two tube sheets and a plurality of gas guide tubes for the passage of the reaction gas, and the oxygen is supplied to the space around and between the gas guide tubes, i) orthogonal to the gas guide tubes at least one baffle is arranged, which divides the gap in at least two distribution spaces, wherein the distribution spaces are fluidly interconnected or merged through one or more openings, and ii) at least one gas conduit leads into the first distribution space in the flow direction, via which d it is supplied with oxygen, and iii) in the flow direction of the lower tube plate is provided with a plurality of openings in the form of nozzles, bores or the like, through which the oxygen can leave the gap, iv) below the lower tube plate, a solids-free gas mixing zone is provided ,

Here, the distance between nozzles, holes or the like to the surface of the catalyst filling matched to the respective streams is best at least 40 mm, not more than 250 mm, but preferably 120 mm.

With increasing temperature difference between oxygen-containing gas and reaction gas, the synthesis reactor can be improved to the effect that a plurality of baffles are used. The baffles are best inclined so that above the holes or nozzles in the radial direction an equal distribution of pressure takes place.

In an improved variant it is provided that the bores or nozzles, which are arranged in the lower tubesheet, are inclined out of the vertical. The inclination is ideally in the tangential direction. As a result, a direct flow against the reactor walls is avoided.

[0014] A further improvement is to provide each bore or align nozzles so that it is directed towards the axis of a single gas guide tube below the outlet of that respective gas guide tube, thereby ensuring that each individual reaction gas jet has at least one O 2 ₂ - jet is provided as a direct reaction partner. In the mixing zone below the lower tube plate, a large number of small-scale mixing zones are formed during normal operation. It can also be provided that a plurality of holes or nozzles are directed to the axis of a gas guide tube below the outlet of this respective gas guide tube.

In an advantageous embodiment, the gas guide tubes for the passage of the reaction gas to each other in the form of concentric rings within the reactor are arranged. In this case, the effectiveness of the mixing operations in the mixing zone can be improved if the gas guide tubes are arranged at an angle of 45 °, 30 ° or 60 ° to each other.

The invention further comprises a process using a synthesis reactor according to one of the aforementioned embodiments, wherein the oxygen, the individual nozzle with a gas velocity of at least 60 m / s, preferably at least 100 m / s and ideally at least 140 m / s leaves.

In a preferred variant of the method, the oxygen is completely or almost completely mixed with the reaction gas emerging from the gas guide tubes prior to entry into the catalyst filling. The aim is to obtain the most uniform possible mixing of oxygen-containing gas and reaction gas before the mixture enters the catalyst bed so that the desired reaction proceeds as optimally as possible within the catalyst charge. If the mixing is not ideal, streaks which have a higher or lower oxygen concentration than with an ideal mixture strike the catalyst bed surface locally. The quality of the mixing can thus be expressed on the basis of the local deviations of the oxygen concentration in the gas mixture from the ideal mixing average oxygen concentration at the catalyst bed surface. An almost complete mixing is achieved if local oxygen concentrations in the mixture of reaction gas and supplied oxygen on entering the catalyst layer have a minimum oxygen concentration of 60% of the mean oxygen concentration with ideal mixing. below. Preferably, it should be above 80% and even more preferably above 90% of the average O ₂ concentration.

[0018] The method may be improved in that the temperature difference of the oxygen within the Sauerstoffverteilelements upon exit into the gas mixing zone at all the nozzles is less than 100 ⁰ C. Preferably, the temperature difference is less than 50 ⁰ C and it is ideally less than 30 ⁰ C. The flow of nozzles is influenced by the operating conditions such as pressure and temperature and in turn dependent thereon properties such as density and viscosity. With uniform admission pressure, the more evenly the temperature distribution of the oxygen-containing gas within the oxygen distribution element is achieved, all the more uniformly across all the nozzles.

The reason for the unequal distribution of the oxygen temperature within the oxygen distribution elements is that the oxygen fed into the distribution element and the reaction gas guided through the gas guide tubes of the oxygen distribution element have a different temperature as a result of the process. Therefore, an indirect heat exchange between oxygen and reaction gas takes place via the gas guide tubes. Since diameters of up to several meters can be realized in real reactors, high temperature differences occur at the individual nozzles due to the different flow paths and the associated different residence times of the oxygen starting from the feed points in the oxygen distributor element up to the outlet nozzles. These temperature differences at the outlet nozzles in turn cause a different nozzle flow, which in turn leads to an unequal distribution of oxygen over the reactor cross-section. With the previous designs, it is not possible to achieve such a uniform temperature of the oxygen-containing gas within the oxygen distribution element.

The best method is thus carried out such that a heat exchange between the incoming oxygen to the gas guide tubes and in the space around the gas guide tubes, so that the oxygen entering the gas mixing chamber is substantially the same temperature as the reaction gas at this point having.

In Fig. 1, the synthesis reactor according to the invention and the distribution device 1 contained therein is shown in a sectional view in a specific embodiment in a sectional view. The distributor device 1 is introduced in a synthesis reactor, which is only partially shown. Evident is the outer wall 2 of the synthesis reactor, which has in the region of the support of the distributor device 1, a flange 3, the Syn- thesereaktor into an upper reactor segment 4 and a lower reactor segment 5 shares. At a certain distance below the distributor device 1 and in the region of the lower reactor segment 5, a catalyst bed 6 is arranged. The gas space below the distributor device 1 represents the mixing zone 7, in which the reaction gas and the oxygen are mixed and then flow through the catalyst bed 6, where there takes place the actual synthesis reaction. After the catalyst bed 6, the gas is deflected in a manner not shown at the bottom of the synthesis reactor in the central tube 8 and leaves the synthesis reactor through an outlet opening, not shown, wherein the direction of gravity is indicated by 9.

The main elements of the distributor device 1 shown in FIG. 1 are an annular distributor body 10 comprising an upper tube plate 11 and a lower tube plate 12, as well as a plurality of gas conduits 13 leading into the distributor body 10, wherein in FIG Gas line 13 is shown. In the distributor body 10, a plurality of vertical gas guide tubes 14 are arranged, which allow the flow through the distributor body 10 by connecting the interior of the upper reactor segment 4 with the mixing zone 7. In the lower tube sheet 12, a plurality of nozzles 15 are arranged, the number of which is identical to the gas guide tubes 14. Furthermore, parallel to the tubesheets 11 and 12 and perpendicular to the gas guide tubes 14, a concentric baffle 17 in the manifold body 10 is mounted, that the inner space of the manifold body 10 divided into an upper manifold chamber 18 and a lower manifold chamber 19. The two spaces are fluidly connected to each other in the region of the central tube wall 20.

In normal operation, oxygen-containing gas is passed in the direction of arrow 16 through the gas line 13 and into the interior of the distributor body 10. Through the baffle 17, the oxygen-containing gas is passed in the upper distribution chamber 18 radially in the direction of the central tube 8, wherein the gas guide tubes 14 are flowed around and a heat exchange takes place. Subsequently, the oxygen-containing gas enters the lower distributor chamber 19 at the end of the guide plate 17 in the vicinity of the central tube wall 20 and leaves it via the nozzles 15, which lead into the mixing zone 7. There, the oxygen-containing gas meets with the reaction gas, which flows in the direction of arrow 21 from the upper reactor segment 4 and through the gas guide tubes 14 into the mixing zone 7. The mixture of oxygen-containing gas and reaction gas flows in the direction of arrow 22 through the catalyst bed 6, where the actual synthesis reaction takes place.

Fig. 2 is a plan view of the lower tube sheet 12 from below, with only a portion is shown. It can be seen that the gas guide tubes 14 and the sen 15 are arranged on concentric circular paths 23 and 24. The gas guide tubes 14 and the nozzles 15 thereby form an alternating sequence along a circular path.

In the sectional view of Fig. 3, the same lower tube sheet 12 is shown to illustrate the inclination of the nozzles The axis of rotation 25 of the nozzles 15 is inclined α from the vertical at an angle and directed to the axis of rotation 26 of a directly adjacent gas guide tube 14. Thus, an oxygen-rich gas jet, which comes from the lower distributor chamber 19 and is discharged via a nozzle 15 with a high momentum and into the mixing zone 7, each hits a reaction gas jet which enters the mixing zone 7 vertically from above via a gas guide tube 14. These two gas jets meet at a certain distance below the lower tube bottom 12 to each other and are mixed before the mixture enters the catalyst 6 bulk.

[00261 Reference list

1 distributor device

2 outer wall

3 flange

4 reactor segment (upper)

5 reactor segment (lower)

6 catalyst bed

7 mixing zone

8 central tube

9 direction of gravity

10 distributor body

11 upper tube sheet

12 lower tubesheet

13 gas line

14 gas guide tube

15 nozzle

16 arrow, flow direction

17 baffle

18 distribution room (upper)

19 distribution room (lower)

20 central tube wall

21 arrow, flow direction

22 arrow, flow direction

23 circular path

24 circular path

25 rotation axis

26 rotation axis

Claims

claims

1. synthesis reactor, comprising a device for the injection of oxygen, which can be presented in pure form, as air, or mixed with inert gas or water vapor, in a reaction gas, which can flow through the synthesis reactor, for example, use in an oxydehydrogenation plant, wherein oxygen and reaction gas have different temperatures, wherein in the flow direction of the reaction gas before the means for receiving a catalyst filling a distributor element is provided, comprising a manifold body, two tube plates and a plurality of gas guide tubes for passage of the reaction gas, and the oxygen is supplied to the space between the gas guide tubes, characterized in that

^■ the gas guide tubes, at least one baffle is arranged orthogonally, which divides the space into at least two distribution chambers, the distribution chambers are fluidically connected to one another by one or more openings, or around one another Ü mountain

^At least one gas line leads into the first distributor space in the flow direction, via which the oxygen can be supplied, and

^{Is provided} in the flow direction of the lower tube sheet with a plurality of openings in the form of nozzles, bores or the like, through which the oxygen can leave the gap, wherein

^■ a solids-free gas mixing zone is provided below the lower tube plate.

2. Synthetic reactor according to claim 1, characterized in that the distance between the bores or openings from the surface of the catalyst filling is at least 40 mm, at most 250 mm, but preferably 120 mm.

3. synthesis reactor according to claim 1 or 2, characterized in that the bores or nozzles, which are arranged in the lower tube sheet, are inclined from the vertical.

4. synthesis reactor according to claim 3, characterized in that the bores or nozzles are inclined in tangential direction from the vertical.

5. synthesis reactor according to claim 3 or 4, characterized in that each bore or nozzle directed towards the axis of a single gas guide tube below the outlet of this respective gas guide tube, wherein a plurality of holes or nozzles on the axis of a gas guide tube below the outlet of this respective gas guide tube can be directed.

6. Synthetic reactor according to one of claims 1 to 5, characterized in that the gas guide tubes for the passage of the reaction gas to each other in the form of concentric rings are arranged within the reactor.

7. synthesis reactor according to one of claims 1 to 6, characterized in that the gas guide tubes are arranged to each other at an angle of 45 ° or 30 ° or 60 °.

8. Process using a synthesis reactor according to one of the preceding claims, characterized in that the oxygen leaves the individual nozzle at a gas velocity of at least 60 m / s, preferably at least 100 m / s and even more preferably at least 140 m / s.

9. The method according to claim 8, characterized in that the oxygen is completely or almost completely mixed with the exiting the gas guide tubes reaction gas before entering the catalyst filling, with an approximately complete mixing is achieved when the minimum occurring oxygen concentration in the gas over 60%, preferably over 80% and even more preferably over 90% of the average oxygen concentration.

10. The method according to claim 8 or 9, characterized in that the temperature of the oxygen at entry into the gas mixing zone at all nozzles is equal or approximately equal, with an approximately same temperature is reached when the temperature difference between the nozzles less than 100 ⁰ C. , Preferably less than 50 ⁰ C and even more preferably less than 30 ⁰ C.

11. The method according to any one of claims 8 to 10, characterized in that a heat exchange between the inflowing oxygen to the gas guide tubes and in the space around the gas guide tubes is made such that the oxygen when entering the gas mixing chamber substantially the same temperature as the reaction gas has at this point.