Temperature control reactor

Abstract

The invention discloses a temperature control reactor which solves the technical problems that an existing reactor is complex in structure, the heat transfer capacity needs to be further improved, and a catalyst is not easy to load and unload. According to the technical scheme, the heat exchanger comprises a shell provided with a shell pass inlet and a shell pass outlet and a plurality of heat exchange tubes in the shell, the heat exchange tubes are filled with catalyst layers, each heat exchange tube is composed of a spiral winding section in the middle and tube nest sections on the two sides, the tail ends of the tube nest sections on the two sides are connected with an upper annular tube gathering device and a lower annular tube gathering device respectively, and the upper annular tube gathering device and the lower annular tube gathering device are connected. And the upper annular manifold device and the lower annular manifold device are respectively connected with a medium pipe orifice on the shell. The reactor is extremely simple in structure, high in heat exchange efficiency, high in conversion per pass, controllable in reaction depth and simple and dead-angle-free in catalyst loading and unloading.

Description

Technical Field

[0001] The invention relates to a chemical reactor, in particular to a temperature-controlled reactor. Background Art

[0002] For reactions that are controlled by thermodynamic equilibrium and have a huge exothermic heat, such as methanation, the heat transfer and temperature control capabilities of the reactor are crucial. Experimental studies have shown that for methanation, under almost the same inlet composition and operating conditions, the outlet temperature of a reactor with excellent heat transfer capabilities is more than 300°C lower than that of an adiabatic reactor, and the outlet carbon conversion rate is more than 50% higher.

[0003] As far as heat transfer reactors are concerned, although traditional shell-and-tube reactors have been widely used in industrial production, their low heat transfer efficiency can easily lead to local heat concentration and uneven thermal stress distribution, which can cause tube burning or even pull the heat exchange tube off the tube plate, resulting in shell-and-tube medium leakage. In recent years, wound-tube reactors have gradually been used in industrial production due to their advantages such as large heat exchange area per unit volume and thermal stress dispersion. Existing patents disclose some design types of wound-tube reactors. Patent CN213528584U discloses a layered wound-tube isothermal reactor, which has high heat transfer efficiency and solves the problem of thermal expansion. However, this type of reactor has obvious defects such as complex internal winding structure, messy arrangement of the manifold section, and inconvenience for catalyst loading and unloading.

[0004] In order to increase the depth of reaction, multiple reactors are usually connected in series in industrial production. For example, patent CN103373887B discloses an isothermal methanation reactor, which increases the depth of reaction by connecting an adiabatic reactor in series thereafter. Patent CN213824710U discloses a vinyl chloride synthesis reactor, which couples a shell-and-tube reactor and an adiabatic reactor into one; similarly, patent CN206553480U discloses a multi-stage integrated methanation reactor, which couples two shell-and-tube reactors into one. However, due to the coupling of multiple reaction beds, the above reactor introduces an inter-stage mixing zone, thereby increasing the reactor volume and equipment cost. Patent CN216770279U discloses a tube bundle, a heat exchanger and a horizontal reactor, which has the defects of complex structure and difficulty in uniformly loading the catalyst. Summary of the invention

[0005] The purpose of the present invention is to solve the above technical problems and to provide a temperature-controlled reactor with extremely simple structure, high heat exchange efficiency, high single-pass conversion rate, controllable reaction depth, simple catalyst loading and unloading and no dead angle.

[0006] The temperature-controlled reactor of the present invention comprises a shell provided with a shell inlet and an outlet and a plurality of heat exchange tubes in the shell, the heat exchange tubes are filled with a catalyst layer outside, the heat exchange tubes are composed of a spirally wound section in the middle section and tube array sections on both sides, the ends of the tube array sections on both sides are respectively connected to an upper annular manifold and a lower annular manifold, and the upper and lower annular manifolds are respectively connected to the medium pipe openings on the shell.

[0007] A central tube is axially arranged at the center of the shell, and a plurality of heat exchange tubes are evenly arranged along the outer periphery of the central tube.

[0008] The outer sides of the upper and lower annular manifolds are correspondingly provided with detachable upper and lower gas distribution orifice plates.

[0009] Along the gas flow direction, ceramic ball layers are filled at both ends of the shell between the upper and lower gas distribution orifice plates, at least one catalyst layer is filled in the middle section, and ceramic ball layers are required to be filled at both ends. Two adjacent catalyst layers are also separated by ceramic ball layers.

[0010] The shell side between the upper and lower gas distribution orifice plates is divided into a heat transfer and temperature control area with heat exchange tubes and an insulation area without heat exchange tubes. The insulation area is only filled with a ceramic ball layer or at most two catalyst layers, and the heat transfer and temperature control area is at least filled with one catalyst layer.

[0011] The catalyst layer in the heat-insulating area uses a shift catalyst; the catalyst layer in the heat-transferring and temperature-controlling area uses a sulfur-resistant methanation catalyst.

[0012] The shell inlet and outlet on the shell are located at two ends of the shell, and the two ends of the central tube are closed.

[0013] The shell side inlet and outlet on the shell are located at the top of the shell, the upper end of the central tube is connected with the shell side inlet, and the lower end is connected with the shell side through the lower gas distribution orifice plate.

[0014] The top end and the bottom end of the shell are detachable.

[0015] In view of the problems existing in the background technology, the inventor has made the following improvements:

[0016] 1) The heat exchange tube is designed to consist of a spirally wound section in the middle section and tube sections on both sides. The spirally wound section in the middle section can greatly increase the heat exchange area, effectively eliminate the thermal stress of the reactor internals, and extend the service life of the reactor and the catalyst. The tube sections on both sides can provide a larger catalyst filling space, which is convenient for catalyst filling.

[0017] 2) The problem that the tube sheet structure of the heat exchange tubes installed in the reactor in the past was complex and inconvenient for catalyst loading was solved. The upper annular manifold and the lower annular manifold were used to replace the traditional tube sheet, and the two ends of the heat exchange tube were connected to the corresponding upper and lower annular manifolds and then connected to the pipe openings on the shell. The detachable upper and lower gas distribution orifice plates and the cover plates at both ends of the shell are combined to make the bed layer directly connected to the top space, thereby completely opening up the catalyst loading and unloading channel, facilitating the rapid loading and unloading of the catalyst, avoiding filling dead corners, and further improving the reaction rate.

[0018] 3) The prior art usually limits the reaction area to the area between the two tube sheets where the heat exchange tubes are provided. However, the inventors have overcome the prejudice and divided the shell side between the upper and lower gas distribution orifice plates into a heat transfer and temperature control area with heat exchange tubes and an insulation area without heat exchange tubes. The insulation area has the characteristics of high space utilization, large catalyst loading, and simple loading, which is suitable for reaction scenarios with small reaction heat effect. The heat transfer and temperature control area has the characteristics of relatively uniform axial temperature. The inventors can use the above characteristics to set one or more catalyst layers in the same area and different catalyst layers in different areas, realize coupling multiple reactions in one reactor, flexibly control the reaction depth, extend the catalyst loading area, and achieve the effect of different characteristic reactions occurring at different positions of the reactor. The reactor partitioning is realized without adding complex internal components, thereby improving the reactor utilization rate. Preferably, the insulating area is only filled with a porcelain ball layer or at most two catalyst layers, and the heat transfer and temperature control area is at least filled with one catalyst layer. When more than two catalyst layers are filled, the filled catalysts can be the same or different. Each catalyst layer is separated by a porcelain ball layer. For reactions with faster reaction rates, the reaction depth of each bed layer can be well controlled to achieve the purpose of controlling the bed temperature; a conversion catalyst is used in the catalyst layer in the insulating area, and a sulfur-resistant methanation catalyst is used in the catalyst layer in the heat transfer and temperature control area.

[0019] 5) The shell side inlet and outlet on the shell can be located at both ends of the shell respectively or both are set at the top of the shell. When the shell side inlet and outlet are both set at the top of the shell, the central tube can be used as an air inlet channel to allow the raw gas to pass through the central tube for preheating before being sent into the shell side at the bottom of the shell.

[0020] In summary, the present invention has an extremely simple structure, high heat exchange efficiency, high single-pass conversion rate, controllable reaction depth, simple catalyst loading and unloading, and no dead ends, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of Example 1 of the present invention.

[0022] Figure 2 This is a schematic diagram of the filling structure of the catalyst in Example 1 of the present invention.

[0023] Figure 3 This is a schematic diagram of the structure of Example 2 of the present invention.

[0024] Figure 4 This is a schematic diagram of the filling structure of the catalyst in Example 2 of the present invention.

[0025] Among them, 1. shell inlet; 2. bottom; 3. upper gas distribution orifice; 4. upper annular manifold; 5. medium pipe mouth; 6. shell; 7. heat exchange tube; 7.1. spiral winding section; 7.2. tube section; 8. center tube; 9. top; 10. shell outlet; 11. lower gas distribution orifice; 12. lower annular manifold; 13. catalyst layer; 14. porcelain ball layer. DETAILED DESCRIPTION

[0026] The present invention will be further explained below in conjunction with the accompanying drawings:

[0027] Embodiment 1:

[0028] See also Figure 1 The temperature control reactor comprises a shell 6 with a shell inlet and outlet 1 and 10 at both ends, and a plurality of heat exchange tubes 7 in the shell 6. The cover plates at the top 9 and the bottom 2 of the shell 6 are both removable. The center of the shell 6 is provided with a central tube 8 with closed ends in the axial direction, and the plurality of heat exchange tubes 7 are evenly arranged along the outer periphery of the central tube. The heat exchange tube 7 is composed of a spiral winding section 7.1 in the middle section and a tube array section 7.2 on both sides. The length of the spiral winding section accounts for 60% to 96% of the overall length of the heat exchange tube. The ends of the tube array sections 7.2 on both sides are respectively connected to an upper annular manifold 4 and a lower annular manifold 12. The upper and lower annular manifolds 4 and 12 are respectively connected to the medium pipe opening 5 on the shell 6. The outer sides of the upper and lower annular manifolds 4 and 12 are correspondingly provided with detachable upper and lower gas distribution orifice plates 3 and 11.

[0029] The shell side outside the heat exchange tube 7 is filled with a catalyst layer. Specifically, along the gas flow direction, the two ends of the shell side between the upper and lower gas distribution orifice plates 3 and 11 are filled with a ceramic ball layer 14, and the middle section is filled with at least two layers of catalyst layers 13. The two adjacent catalyst layers 13 are separated by a ceramic ball layer 14. Further, the shell side between the upper and lower gas distribution orifice plates 3 and 11 is divided into a heat transfer and temperature control area with heat exchange tubes 7 and an insulation area without heat exchange tubes. The insulation area is only filled with a ceramic ball layer or at most two layers of catalyst layers 13, and the heat transfer and temperature control area is filled with at least one layer of catalyst layer 13.

[0030] See also Figure 2In the figure, the blue area is the ceramic ball layer 14, and the yellow area is the catalyst layer 13. In this embodiment, the upper insulation area is filled with only the ceramic ball layer 14, the middle heat transfer temperature control area is filled with a catalyst layer 13 (sulfur-resistant methanation catalyst), and the lower insulation area is filled with a catalyst layer 13 (conversion catalyst). By adjusting the space velocity and the catalyst loading amount, the reaction depth can be conveniently controlled to achieve the specified hydrogen-carbon ratio.

[0031] With the structure of the present invention, when filling the catalyst and the porcelain balls, it is only necessary to remove the cover plate at the top end 9 of the shell 6 and the upper gas distribution orifice plate 3, and then the catalyst and the porcelain balls can be directly poured or loaded with the aid of a guide tube. It is also possible to load multiple material tubes at the same time by dividing the area, which not only speeds up the loading speed, but also ensures that the loading progress of each area is consistent, so that the loading is uniform. After the loading is completed, the upper gas distribution orifice plate 3 and the cover plate at the top end 9 can be installed. At the same time, if the loaded catalyst and porcelain balls need to be unloaded, the cover plate at the bottom end 2 and the lower gas distribution orifice plate 11 can be removed to allow the catalyst and the porcelain balls to be unloaded by gravity, which is extremely convenient to operate.

[0032] During operation, the raw gas (raw gas containing CO, CO 2 , H 2 O, H 2 and other inert components) enters from the shell side inlet 1 at the bottom 2 through the shell side 6, is evenly distributed through the lower gas distribution orifice 11, and then passes through the porcelain ball layer 14 and catalyst layer 13 in the insulation zone of the lower section in turn (controllable conversion reaction is carried out under the action of the conversion catalyst), the catalyst layer 13 in the heat transfer and temperature control zone of the middle section (methanation reaction is carried out under the action of the sulfur-resistant methanation catalyst, and the reaction heat is removed by the heat exchange tube 7), the porcelain ball layer 14 in the insulation zone of the upper section, and finally is led out from the upper shell side outlet 10 at the top 9 through the upper gas distribution orifice 3.

[0033] The heat exchange medium enters from the medium pipe port 5 of the lower section of the shell side 6 through the lower annular manifold 12 and enters into a plurality of heat exchange tubes 7 for heat exchange, and then passes through the upper annular manifold 4 and finally is led out from the medium pipe port 5 of the upper section of the shell side 6.

[0034] Methanation experiments show that the inlet temperature of the raw gas is 200℃~290℃ after upstream heat exchange, and the carbon concentration (CO+CO 2 ) is between 3% and 9%, and circulating hot water is added to the tube by forced circulation, with a circulation ratio of 5 to 20. The heat generated by methanation is removed by producing 4MPa to 6MPa saturated steam. 2 The one-way conversion rate can reach over 99.9%.

[0035] Embodiment 2:

[0036] See also Figure 3Different from Example 1, the shell side inlet and outlet 1, 10 are both located at the top end 9 of the shell 6, the upper end of the central tube 8 is connected to the shell side inlet 1, and the lower end is connected to the shell side 6 through the lower gas distribution orifice 11. The catalyst is filled in the following manner: the partially spirally wound section 7.1 in the middle section of the heat exchange tube 7 is filled with the catalyst 13 (filled with a 3mm*3mm cylindrical type I methanation catalyst, whose active components are a composite oxide composed of nickel oxide and silicon carbide, and whose loading amount is 30wt% to 45wt%, and whose main function is to almost completely convert the raw gas with a high carbon concentration, and at the same time to dissipate the reaction heat by virtue of its high thermal conductivity), and the entire tube section 7.2 on the upper side of the reactor is filled with the catalyst 13 (filled with a hollow cylindrical type II methanation catalyst, with an inner diameter, an outer diameter, and a height of 2mm, 4mm, and 4mm respectively, and whose active components are a composite oxide composed of nickel oxide and cerium oxide, and whose loading amount is 25wt% to 35wt%, and whose main function is to further convert the raw gas that has not been completely converted in the upper bed layer, thereby improving the single-pass conversion rate, and at the same time using a hollow structure to reduce the bed pressure drop), the two catalyst layers 13 are separated by porcelain balls 14, and the remaining fillable areas are filled with porcelain balls 14. The catalytic performance of the above two catalyst layers is different. It should be noted that the ceramic ball layer 14 between the two methanation catalyst layers 13 should cover the connection area between the spiral winding pipe section 7.1 and the array pipe section 7.2. Figure 4 .

[0037] The raw gas is introduced into the shell side inlet 1 at the top 9 of the shell body 6, passes downward through the center tube 8 into the bottom of the shell side, and then passes upward through the lower gas distribution orifice plate 11 along the circumference of the center tube 8 into the lower section of the porcelain ball layer 14, the catalyst layer 13, the connecting section of the porcelain ball layer 14, the catalyst layer 13, and the upper section of the porcelain ball layer 14. The product gas after the reaction passes through the upper gas distribution orifice plate 3 and is then led out through the shell side outlet 10 at the top 9 of the shell body 6.

[0038] Under typical coke oven gas carbon concentration conditions (CO+CO 2 The inlet temperature of the raw gas is 150℃~250℃ after upstream heat exchange, and the raw gas reaches the activation temperature of the catalyst bed through the preheating of the central tube 8 and the heating of the tube section 7.2 at the lower side of the heat exchange tube 7. After the bed reaction, the outlet CO+CO 2 The concentration is less than 70ppm.

Claims

1. A temperature-controlled reactor, comprising a shell provided with a shell inlet and an outlet and a plurality of heat exchange tubes in the shell, wherein a catalyst layer is filled outside the heat exchange tubes, characterized in that: The heat exchange tube consists of a spirally wound section in the middle and tube sections on both sides. The ends of the tube sections on both sides are respectively connected to an upper annular manifold and a lower annular manifold, and the upper and lower annular manifolds are respectively connected to the medium pipe openings on the shell.

2. The temperature-controlled reactor according to claim 1, characterized in that A central tube is axially arranged at the center of the shell, and a plurality of heat exchange tubes are evenly arranged along the outer periphery of the central tube.

3. The temperature-controlled reactor according to claim 1, characterized in that The outer sides of the upper and lower annular manifolds are correspondingly provided with detachable upper and lower gas distribution orifice plates.

4. The temperature-controlled reactor according to any one of claims 1 to 3, characterized in that: Along the gas flow direction, ceramic ball layers are filled at both ends of the shell between the upper and lower gas distribution orifice plates, at least one catalyst layer is filled in the middle section, and ceramic ball layers are required to be filled at both ends. Two adjacent catalyst layers are also separated by ceramic ball layers.

5. The temperature-controlled reactor according to claim 4, characterized in that The shell side between the upper and lower gas distribution orifice plates is divided into a heat transfer and temperature control area with heat exchange tubes and an insulation area without heat exchange tubes. The insulation area is only filled with a ceramic ball layer or at most two catalyst layers, and the heat transfer and temperature control area is at least filled with one catalyst layer.

6. The temperature-controlled reactor according to claim 5, characterized in that The catalyst layer in the heat-insulating area uses a shift catalyst; the catalyst layer in the heat-transferring and temperature-controlling area uses a sulfur-resistant methanation catalyst.

7. The temperature-controlled reactor according to claim 4, characterized in that The shell inlet and outlet on the shell are located at two ends of the shell, and the two ends of the central tube are closed.

8. The temperature-controlled reactor according to claim 4, characterized in that The shell side inlet and outlet on the shell are located at the top of the shell, the upper end of the central tube is connected with the shell side inlet, and the lower end is connected with the shell side through the lower gas distribution orifice plate.

9. The temperature-controlled reactor according to claim 1, characterized in that The top end and the bottom end of the shell are detachable.

10. The temperature-controlled reactor according to claim 1, characterized in that: The length of the spirally wound section accounts for 60% to 96% of the overall length of the heat exchange tube.

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