An efficient shell-and-tube water-cooled methanol synthesis reactor

Abstract

The present invention provides an efficient shell-and-tube water-cooled methanol synthesis reactor. An adiabatic reaction bed layer is provided inside the lower head. The adiabatic reaction bed layer includes extended heat exchange tubes, and the extended heat exchange tubes are communicated with the tube bundle. A tube sheet is provided at the lower end of the extended heat exchange tubes. A catalyst loading layer and an inert porcelain ball layer are sequentially arranged below the tube sheet. A partition cavity is provided between the catalyst loading layer and the lower head. The tube sheet is a floating tube sheet, and the floating tube sheet is fixedly connected to the partition cavity. The floating tube sheet and the partition cavity are both in contact with the lower head. The beneficial effects of the present invention are as follows: It avoids the over-temperature risk of the adiabatic reaction catalyst, and at the same time solves the problem of difficult temperature increase at the end of the catalyst life in the methanol synthesis device. During the catalyst life cycle, the attenuation of the synthesis reaction is slow, so that the methanol production is maintained at a relatively high level all the time, improving the economic benefits of the device; while improving the internal space utilization rate of the reactor, it does not increase the equipment investment cost, and at the same time increases the catalyst loading amount of the reactor.

Description

Technical Field

[0001] The present invention belongs to the technical field of methanol synthesis, and particularly relates to a high-efficiency shell-and-tube water-cooled methanol synthesis reactor. Background Art

[0002] The traditional methanol synthesis process mainly includes steps such as compression and purification, methanol synthesis, heat recovery, cooling, methanol separation and flashing, methanol recovery, and hydrogen recovery. The main process route is to prepare methanol by the reversible exothermic reaction of syngas in a synthesis reactor in the presence of a catalyst. The syngas leaving the reactor first preheats the syngas entering the reactor, and then is cooled and separated to produce methanol. The remaining gas continues to be returned to the compressor for boosting pressure and then circulates and reacts in the synthesis loop. Fresh gas is continuously supplemented in the synthesis loop, and purge gas is discharged at the same time to avoid the accumulation of inert gas in the synthesis loop. The most core part of the methanol synthesis device is the synthesis reactor. In the currently commonly used shell-and-tube water-cooled methanol synthesis reactor, the CuO / ZnO-based catalyst is filled in the shell-and-tube fixed bed, and the reaction heat is supplied to the boiler water in the shell side to generate high-pressure saturated steam, and the reaction temperature is controlled by the pressure of the boiling water in the shell side of the reactor.

[0003] Among the process parameters used to regulate the methanol synthesis reaction process, temperature has a great influence on both the reaction equilibrium and rate. For this reversible exothermic reaction of methanol synthesis, when the temperature increases, the reaction rate constant can increase, but the equilibrium constant will decrease. When the composition of the reaction mixture is fixed and the operating temperature is changed, the reaction rate is affected by these two conflicting factors at the same time. Since the reaction rate constants and equilibrium constants of the reactions of CO to methanol and CO2 to methanol are different, the optimal temperatures of the two reactions are also different under the same composition. Under a certain composition condition, the temperature at which the sum of the two reaction rates is the largest is the optimal temperature of the reaction system.

[0004] However, it should be noted that after entering the middle and late stages of the catalyst, the activity of the catalyst gradually decreases, and the reaction rate also decreases accordingly, ultimately resulting in a gradual reduction in the methanol production of the reactor. The current conventional method is to gradually increase the temperature of the syngas entering the reactor to increase the reaction temperature in the reactor, so as to maintain the economic output of the methanol synthesis device. However, in the current traditional methanol synthesis reaction process, it is difficult for the syngas entering the reactor to reach the required temperature at the end of the catalyst, so it is difficult to maintain a high conversion rate, and the catalyst is not fully utilized.

[0005] If a layer of catalyst for adiabatic reaction is filled in the inlet section of the reactor, the temperature of the syngas entering the tube section of the reactor at the initial stage of the catalyst will be very high. At the same time, the degree of temperature increase cannot be controlled (the adiabatic reaction syngas directly enters the tubes), and there is a risk of local overheating of the catalyst (the reaction driving force of the fresh syngas at the inlet is the largest, the heat release of the reaction is large, the temperature rises rapidly in the adiabatic reaction, and theoretically, the temperature rise generated by the reaction of every 1 mole% of CO to produce methanol is about 32°C). And the catalyst has high activity at the initial stage, and generally there is no need to increase the temperature of the inlet syngas. At this time, once the top of the reactor tube overheats, on the one hand, the overheated syngas will cause a risk of overheating of the upper tube sheet of the reactor, and on the other hand, the overheated syngas directly enters the tubes, resulting in overheating of the catalyst in the tubes, causing catalyst aging and shortening of the service life. Therefore, generally, the methanol synthesis recycle ratio using this technology is relatively large, and a large operating recycle ratio will lead to an increase in the investment and operating costs of related equipment. More importantly, as the operation time of the catalyst progresses, the activity of the catalyst layer at the inlet of the reactor will start to decline first. Especially at the end of the catalyst life when temperature increase is required, the activity of the catalyst in the inlet adiabatic layer has already decayed completely, making it difficult to solve the problem of difficult temperature increase at the end of the catalyst life as described above. Summary of the Invention

[0006] In view of this, the present invention aims to provide a highly efficient shell-and-tube water-cooled methanol synthesis reactor to solve the problem that after the middle and late stages of the catalyst, the catalyst activity gradually decreases, the reaction rate also decreases accordingly, and finally the methanol production of the reactor gradually decreases, as described in the above background technology.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] An efficient shell-and-tube water-cooled methanol synthesis reactor, comprising a shell, the shell is successively provided with an upper head, a tube body, and a lower head from top to bottom, the upper head and the lower head are both fixedly connected to the tube body, the upper head is provided with a syngas inlet, the lower head is provided with a syngas outlet, an upper tube sheet is arranged between the upper head and the tube body, a lower tube sheet is arranged between the lower head and the tube body, a tube bundle is arranged between the upper tube sheet and the lower tube sheet, a catalyst is filled in the tube bundle, the upper tube sheet and the lower tube sheet are both provided with through holes for the tube bundle to pass through, the upper end of the tube bundle is communicated with the upper head, the lower end of the tube bundle is communicated with the lower head, both ends of the tube bundle are hermetically connected to the upper tube sheet and the lower tube sheet, an adiabatic reaction bed layer is arranged in the lower head, the adiabatic reaction bed layer includes extended heat exchange tubes, the extended heat exchange tubes are communicated with the tube bundle, a tube sheet is arranged at the lower end of the extended heat exchange tubes, a catalyst filling layer and an inert porcelain ball layer are successively arranged below the tube sheet, a partition cavity is arranged between the catalyst filling layer and the lower head, the tube sheet is a floating tube sheet, the floating tube sheet is fixedly connected to the partition cavity, and both the floating tube sheet and the partition cavity are abutted against the lower head. The setting of the adiabatic reaction bed layer increases the reaction temperature at the end stage of the catalyst to strengthen the synthesis reaction. Because according to the methanol synthesis reaction kinetics, the reaction driving force at the end of the reactor tube bundle is small, so the reaction heat release is stable at the adiabatic layer of the catalyst at the end of the tube bundle, thereby increasing the reactor outlet temperature but with a lower risk of overheating. Moreover, the performance attenuation of the catalyst at the reactor outlet is slower, and it can remain at a relatively high level even at the end stage of the catalyst. At the same time, by adding a bypass adjustment pipeline on the hot side of the inlet and outlet heat exchanger at the reactor outlet, it is convenient to adjust the situation where the catalyst inlet temperature is too high at the initial stage of the catalyst (when the catalyst activity is high) in the methanol synthesis reactor. The floating tube sheet separates the catalyst filled below from the lower tube sheet of the reactor, preventing the catalyst for this section of adiabatic reaction from approaching the lower tube sheet of the reactor and avoiding the risk of overheating of the lower tube sheet. There is no fixed connection between the floating tube sheet and the partition cavity and the inner wall of the lower head of the shell, only in a physically closed state. This design enables the space between the floating tube sheet and the lower tube sheet of the reactor to communicate with the entire lower head of the reactor, avoiding additional forces on the two tube sheets due to the pressure difference in different regional spaces.

[0009] Further, the floating tube sheet and the partition cavity enclose a cavity for accommodating the catalyst filling layer.

[0010] Further, a catalyst discharge outlet is arranged on the lower head, and manholes are arranged on both the upper head and the lower head.

[0011] Further, the reactor further includes a steam-water circulation mechanism, which includes a steam-water riser pipe interface, a boiler water downcomer pipe interface, and a steam drum. The pipe body is filled with saturated boiler water. The steam-water riser pipe interface is arranged at the upper part of the pipe body, and the boiler water downcomer pipe interface is arranged at the lower part of the pipe body. The steam-water riser pipe interface and the boiler water downcomer pipe interface are communicated with the steam drum. The part between the shell and the tube bundle is the shell side, and the shell side medium is saturated boiler water. The boiler water in the reactor shell side, the steam-water riser pipe, the boiler water downcomer pipe, and the steam drum generates by-product steam through natural circulation, removing the reaction heat in the tubes.

[0012] Further, a syngas inlet distributor is arranged in the upper head.

[0013] Further, a syngas outlet collector is arranged in the lower head.

[0014] Compared with the prior art, the high-efficiency shell-and-tube water-cooled methanol synthesis reactor of the present invention has the following advantages:

[0015] (1) For the high-efficiency shell-and-tube water-cooled methanol synthesis reactor of the present invention, by arranging an adiabatic reaction bed layer, the outlet temperature of the reactor is increased but the over-temperature risk is relatively low, solving the problem of difficult temperature increase at the end of the catalyst in the existing shell-and-tube water-cooled reactor in the traditional methanol synthesis process, making the adjustment and control of the reaction temperature more flexible and efficient in the initial and final stages of the methanol synthesis reaction. During the catalyst life cycle, the synthesis reaction attenuation in the reactor is slow, keeping the methanol production at a relatively high level all the time, improving the economic benefits of the device.

[0016] (2) For the high-efficiency shell-and-tube water-cooled methanol synthesis reactor of the present invention, the floating tube sheet separates the catalyst filled below from the lower tube sheet of the reactor, preventing the catalyst in this section of the adiabatic reaction from approaching the lower tube sheet of the reactor and avoiding the risk of over-temperature of the lower tube sheet.

[0017] (3) For the high-efficiency shell-and-tube water-cooled methanol synthesis reactor of the present invention, the floating tube sheet and the partition chamber are not in a sealed structure with the inner wall of the lower head of the reactor, but only in a physically closed state, and the floating tube sheet does not bear the additional force generated by the pressure difference between the two sides.

[0018] (4) For the high-efficiency shell-and-tube water-cooled methanol synthesis reactor of the present invention, the overall design size of the reactor does not need to be changed, and all the space below the lower tube sheet of the reactor and inside the lower head is utilized. The amount of inert porcelain balls to be filled in the lower head of the reactor is also correspondingly reduced. On the one hand, this will not increase the equipment investment cost, and on the other hand, it can increase the catalyst loading amount of the reactor. Description of the Drawings

[0019] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0020] Figure 1 It is a schematic structural diagram of a high-efficiency shell-and-tube water-cooled methanol synthesis reactor according to an embodiment of the present invention;

[0021] Figure 2 It is a schematic enlarged bottom structure diagram of a high-efficiency shell-and-tube water-cooled methanol synthesis reactor according to an embodiment of the present invention.

[0022] Figure 3 It is a schematic diagram of the arrangement of the tube bundles of a high-efficiency shell-and-tube water-cooled methanol synthesis reactor according to an embodiment of the present invention.

[0023] Explanation of reference numerals:

[0024] 1, shell; 2, catalyst loading layer; 3, floating tube sheet; 4, partition chamber; 5, extended heat exchange tube; 6, syngas inlet; 7, syngas outlet; 8, upper tube sheet; 9, lower tube sheet; 10, tube bundle; 11, steam-water riser interface; 12, boiler water downcomer interface; 13, syngas inlet distributor; 14, syngas outlet collector; 15, catalyst discharge port; 16, manhole; 17, inert porcelain ball layer. Specific embodiments

[0025] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0027] As Figures 1-3As shown in the figure, a high-efficiency shell-and-tube water-cooled methanol synthesis reactor of the present invention includes a shell 1. The shell 1 is successively provided with an upper head, a tube body, and a lower head from top to bottom. The upper head and the lower head are both fixedly connected to the tube body. The upper head is provided with a synthesis gas inlet 6 and a synthesis gas inlet distributor 13. The lower head is provided with a synthesis gas outlet 7, a synthesis gas outlet collector 14, and a catalyst discharge port 15. The upper head and the lower head are both provided with manholes 16. An upper tube sheet 8 is provided between the upper head and the tube body, and a lower tube sheet 9 is provided between the lower head and the tube body. A tube bundle 10 is provided between the upper tube sheet 8 and the lower tube sheet 9. The tube bundle 10 is filled with a catalyst. The upper tube sheet 8 and the lower tube sheet 9 are both provided with through holes for the tube bundle 10 to pass through. The upper end of the tube bundle 10 is communicated with the upper head, and the lower end of the tube bundle 10 is communicated with the lower head. Both ends of the tube bundle 10 are hermetically connected to the upper tube sheet 8 and the lower tube sheet 9. An adiabatic reaction bed layer is provided inside the lower head. The setting of the adiabatic reaction bed layer increases the reaction temperature at the end stage of the catalyst to strengthen the synthesis reaction. Because according to the methanol synthesis reaction kinetics, the reaction driving force at the end of the reactor tube bundle 10 is small, so the reaction heat release is stable at the adiabatic layer of the catalyst at the end of the tube bundle 10, thereby increasing the reactor outlet temperature but with a lower risk of overheating. Moreover, the performance attenuation of the catalyst at the reactor outlet is slower, and it can remain at a relatively high level even at the end stage of the catalyst. At the same time, by adding a bypass adjustment pipeline on the hot side of the inlet and outlet heat exchanger at the reactor outlet, it is convenient to adjust the situation where the catalyst inlet temperature is too high at the initial stage of the catalyst (when the catalyst activity is high) in the methanol synthesis reactor.

[0028] The adiabatic reaction bed layer includes an extended heat exchange tube 5. The extended heat exchange tube 5 is communicated with the tube bundle 10. A floating tube sheet 3 is provided at the lower end of the extended heat exchange tube 5. Below the floating tube sheet 3, a catalyst loading layer 2 and an inert porcelain ball layer 17 are successively provided. A ring-shaped cavity 4 is provided between the catalyst loading layer 2 and the lower head. The cavity 4 is a hollow cavity 4, and the cross-section of the hollow cavity 4 is square. The cavity 4 is fixedly connected to the floating tube sheet 3. Both the floating tube sheet 3 and the cavity 4 are abutted against the lower head. The floating tube sheet 3 and the cavity 4 enclose a cavity for accommodating the catalyst loading layer 2. The floating tube sheet 3 separates the catalyst filled below from the reactor lower tube sheet 9, preventing the catalyst for this section of adiabatic reaction from approaching the reactor lower tube sheet 9 and avoiding the risk of overheating of the lower tube sheet 9. There is no fixed connection between the floating tube sheet 3 and the inner wall of the lower head of the shell 1, and between the cavity 4 and the inner wall of the lower head of the shell 1. It is only in a physically closed state. This design enables the space between the floating tube sheet 3 and the reactor lower tube sheet 9 to be communicated with the entire reactor lower head, avoiding the two tube sheets from bearing additional forces due to the pressure difference in different regional spaces.

[0029] The reactor further includes a steam-water circulation mechanism, which includes a steam-water riser pipe interface 11, a boiler water downcomer pipe interface 12, and a steam drum. The pipe body is filled with saturated boiler water. The steam-water riser pipe interface 11 is arranged at the upper part of the pipe body, and the boiler water downcomer pipe interface 12 is arranged at the lower part of the pipe body. The steam-water riser pipe interface 11 and the boiler water downcomer pipe interface 12 are communicated with the steam drum. The part between the shell 1 and the tube bundle 10 is the shell side, and the shell side medium is saturated boiler water. The boiler water in the reactor shell side, the steam-water riser pipe, the boiler water downcomer pipe and the steam drum generates steam through natural circulation, removing the reaction heat in the tubes.

Claims

1. An efficient shell-and-tube water-cooled methanol synthesis reactor, characterized in that: It includes a shell, which is successively provided with an upper head, a tube body, and a lower head from top to bottom. The upper head and the lower head are both fixedly connected to the tube body. The upper head is provided with a syngas inlet, and the lower head is provided with a syngas outlet. An upper tube sheet is arranged between the upper head and the tube body, and a lower tube sheet is arranged between the lower head and the tube body. A tube bundle is arranged between the upper tube sheet and the lower tube sheet. A catalyst is filled in the tube bundle. The upper tube sheet and the lower tube sheet are both provided with through holes for the tube bundle to pass through. The upper end of the tube bundle is communicated with the upper head, and the lower end of the tube bundle is communicated with the lower head. Both ends of the tube bundle are hermetically connected to the upper tube sheet and the lower tube sheet. An adiabatic reaction bed layer is arranged in the lower head. The adiabatic reaction bed layer includes extended heat exchange tubes, and the extended heat exchange tubes are communicated with the tube bundle. A tube sheet is arranged at the lower end of the extended heat exchange tubes. A catalyst filling layer and an inert porcelain ball layer are successively arranged below the tube sheet. A partition cavity is arranged between the catalyst filling layer and the lower head. The tube sheet is a floating tube sheet, and the floating tube sheet is fixedly connected to the partition cavity. The floating tube sheet and the partition cavity are both abutted against the lower head; The floating tube sheet and the partition cavity enclose a cavity for accommodating the catalyst filling layer; It further includes a steam-water circulation mechanism, which includes a steam-water riser interface, a boiler water downcomer interface, and a steam drum.

2. The efficient shell-and-tube water-cooled methanol synthesis reactor according to claim 1, characterized in that: A catalyst discharge outlet is arranged on the lower head, and manholes are arranged on both the upper head and the lower head.

3. The efficient shell-and-tube water-cooled methanol synthesis reactor according to claim 1, characterized in that: Saturated boiler water is injected into the tube body. The steam-water riser interface is arranged at the upper part of the tube body, and the boiler water downcomer interface is arranged at the lower part of the tube body. The steam-water riser interface and the boiler water downcomer interface are communicated with the steam drum.

4. The efficient shell-and-tube water-cooled methanol synthesis reactor according to claim 1, characterized in that: A syngas inlet distributor is arranged in the upper head.

5. The efficient shell-and-tube water-cooled methanol synthesis reactor according to claim 1, characterized in that: A syngas outlet collector is arranged in the lower head.

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