Evaporation device and application thereof, gas-liquid two-phase complete vaporization treatment method and method for improving hydrogenation conversion rate and selectivity of pyridine

Abstract

The invention relates to the technical field of chemical production, and discloses an evaporation device and application thereof, a gas-liquid two-phase complete vaporization treatment method and a method for improving the hydrogenation conversion rate and selectivity of pyridine. The device comprises an evaporator, a gas-liquid separation tank and an electric heater which are sequentially connected, the evaporator sequentially comprises a distribution unit and a heating unit from bottom to top in the axial direction of the evaporator, the distribution unit comprises a gas distribution pipe which is not parallel to the axial direction of the evaporator, through holes are formed in the pipe wall of the gas distribution pipe, a gas phase inlet is formed in one end of the gas distribution pipe, and a liquid phase inlet is formed in the bottom of the evaporator. After passing through the gas distribution pipe, the gas phase is mixed with the liquid phase and enters the heating unit; a baffle plate is arranged in the gas-liquid separation tank; and the electric heater is communicated with the gas phase outlet of the gas-liquid separation tank and is used for heating the gas phase material flow from the gas-liquid separation tank into superheated steam. The evaporation device can completely vaporize a liquid-phase material flow before the liquid-phase material flow enters a hydrogenation reactor.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production, and in particular to an evaporation device and its application, a treatment method for complete vaporization of gas-liquid two-phases, and a method for improving the conversion rate and selectivity of pyridine hydrogenation. Background Art

[0002] The process of producing piperidine by hydrogenating pyridine is of great significance to the development of my country's DPTT-4 / 6 (dipentamethylenethiuram tetra- or hexasulfide) industry. In this process, ensuring that the pyridine is completely vaporized before entering the reactor is a key factor restricting the production of piperidine by hydrogenating pyridine. Simply mixing hydrogen with pyridine and then heating it through a heat exchanger does not meet the requirements of the reactor device. This is because the mixed pyridine and hydrogen will form gas-liquid stratification after entering the heat exchanger, with pyridine accumulating in the lower layer of the heat exchanger and hydrogen accumulating in the upper layer. Under medium-pressure operating conditions, the boiling point of the accumulated pyridine is above 200°C. When the temperature in the heat exchanger is less than 200°C, the pyridine cannot be completely vaporized. Therefore, it is necessary to develop a device that can completely vaporize the liquid phase before entering the reactor. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problem in the prior art that the liquid phase flow cannot be completely vaporized before entering the reactor, and to provide an evaporation device and its application, a treatment method for complete vaporization of the gas-liquid two-phase, and a method for improving the conversion rate and selectivity of pyridine hydrogenation. The evaporation device can achieve a state in which the liquid phase flow is completely vaporized before entering the hydrogenation reactor.

[0004] In order to achieve the above object, the present invention provides an evaporation device in a first aspect, wherein the device comprises an evaporator, a gas-liquid separation tank and an electric heater connected in sequence;

[0005] From bottom to top along the axial direction of the evaporator, the evaporator includes a distribution unit and a heating unit in sequence. The distribution unit includes a gas distribution pipe arranged non-parallel to the axial direction of the evaporator. The pipe wall of the gas distribution pipe is provided with a through hole. One end of the gas distribution pipe is provided with a gas phase inlet. The bottom of the evaporator is provided with a liquid phase inlet, so that the gas phase passes through the gas distribution pipe, mixes with the liquid phase, and enters the heating unit;

[0006] The gas-liquid separation tank is provided with a baffle;

[0007] The electric heater is connected to the gas phase outlet of the gas-liquid separation tank and is used to heat the gas phase flow from the gas-liquid separation tank into superheated steam.

[0008] Preferably, the through hole has a diameter of 6-30 mm, preferably 8-18 mm.

[0009] Preferably, the number of the through holes is 9-50, preferably 20-45.

[0010] Preferably, the distance between any two adjacent through holes along the axial direction of the gas distribution pipe is 10-36 mm, preferably 15-30 mm.

[0011] Preferably, the first gas-liquid separation tank is provided with 1-5 levels of baffles, preferably 2-4 levels of baffles.

[0012] A second aspect of the present invention provides a method for performing complete gas-liquid two-phase vaporization using the evaporation device described in the first aspect, wherein the method comprises:

[0013] (1) The gaseous raw material is introduced from the gas phase inlet (N4), and the liquid phase raw material is introduced from the liquid phase inlet (N5) at the bottom of the evaporator, so that the gaseous raw material passes through the gas distribution pipe, mixes with the liquid phase raw material, and enters the heating unit for the first heating;

[0014] (2) sending the heated logistics in step (1) into a gas-liquid separation tank for gas-liquid separation;

[0015] (3) The gas phase logistics obtained by gas-liquid separation is sent to an electric heater for secondary heating.

[0016] The third aspect of the present invention provides the use of the evaporation device described in the first aspect or the treatment method described in the second aspect in a gas-liquid two-phase complete vaporization process, preferably in the mixed vaporization of pyridine and hydrogen.

[0017] A fourth aspect of the present invention provides a method for improving the conversion rate and selectivity of pyridine hydrogenation, wherein the method comprises:

[0018] contacting a gaseous mixture of pyridine and hydrogen with a catalyst under pyridine hydrogenation conditions;

[0019] Wherein, the gas phase mixture is obtained by the processing method described in the second aspect above.

[0020] Through the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention constructs a unique and efficient evaporation device system. In this system, the evaporator is designed with a gas distribution pipe with a through hole, so that the gas phase can be evenly distributed in a sufficiently short time. After the logistics is heated in the evaporator, it enters the gas-liquid separation tank. The baffle set in the gas-liquid separation tank guides the liquid entering the pyridine gas-liquid separation tank to keep the liquid level in the separation tank stable. The electric heater performs the final superheated steam conversion on the separated gas phase, so that the entire system can stably and efficiently achieve the goal of complete vaporization of the gas and liquid phases.

[0022] (2) The evaporation device provided by the present invention is used in pyridine hydrogenation to achieve a state where the pyridine is completely vaporized before entering the hydrogenation reactor. Complete vaporization of pyridine is of great significance for the continuous production of piperidine. On the one hand, pyridine and the catalyst are more fully contacted in the hydrogenation reactor, improving the selectivity of piperidine and reducing the pressure on the subsequent separation system. On the other hand, it can reduce the degree of catalyst deactivation and extend the service life of the catalyst, which is of great significance for the efficient and continuous production of piperidine. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the evaporation device;

[0024] Figure 2 It is the structural diagram of the evaporator and the partial enlarged diagram of point C;

[0025] Figure 3 for Figure 2 A front view of the section at point I in the evaporator and cross-sectional views along lines AA and BB;

[0026] Figure 4 Schematic diagram of the structure of the first gas-liquid separation tank.

[0027] Description of Reference Numerals

[0028] N1-discharge port; N2-heating medium inlet; N3-heating medium outlet; N4-gas phase inlet; N5-liquid phase inlet; N6-gas phase discharge port; N7-gas-liquid separation tank inlet; N8-liquid phase discharge port; L1-on-site liquid level gauge; L2-on-site liquid level gauge; P-on-site pressure gauge; T-on-site thermometer; H-hand hole. DETAILED DESCRIPTION

[0029] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0030] In the present invention, unless otherwise specified, directional terms such as "upper, lower, left, right" generally refer to directions shown in the accompanying drawings. "Inside" and "outside" refer to inside and outside relative to the outline of each component itself.

[0031] In the present invention, unless otherwise specified, the "bottom" or "lower end" of the reactor refers to 90-100% of the length of the reactor from top to bottom, and the "upper end" of the reactor refers to 0-10% of the length of the reactor from top to bottom.

[0032] In the present invention, unless otherwise specified, the terms "first" and "second" do not limit the materials, components, or steps, but are used only to distinguish them. For example, the terms "first" and "second" in "first heating" and "second heating" simply indicate that they are not the same heating.

[0033] In the present invention, unless otherwise specified, the various components of the evaporation device are connected by pipelines.

[0034] One aspect of the present invention provides an evaporation device, wherein the device comprises an evaporator, a gas-liquid separation tank and an electric heater connected in sequence;

[0035] From bottom to top along the axial direction of the evaporator, the evaporator includes a distribution unit and a heating unit in sequence. The distribution unit includes a gas distribution pipe arranged non-parallel to the axial direction of the evaporator. The pipe wall of the gas distribution pipe is provided with a through hole. One end of the gas distribution pipe is provided with a gas phase inlet. The bottom of the evaporator is provided with a liquid phase inlet, so that the gas phase passes through the gas distribution pipe, mixes with the liquid phase, and enters the heating unit;

[0036] The gas-liquid separation tank is provided with a baffle;

[0037] The electric heater is connected to the gas phase outlet of the gas-liquid separation tank and is used to heat the gas phase flow from the gas-liquid separation tank into superheated steam.

[0038] The evaporator in the evaporation device provided by the present invention is equipped with a gas distribution pipe with through holes, ensuring uniform distribution of the gas phase within a sufficiently short time. The stream is heated in the evaporator before entering a gas-liquid separator tank. A baffle installed in the separator tank guides the liquid entering the pyridine separator tank, ensuring sufficient gas-liquid separation and maintaining a stable liquid level within the separator tank. An electric heater performs a final superheated steam conversion on the separated gas phase, enabling the entire system to stably and efficiently achieve complete vaporization of both the gas and liquid phases.

[0039] In the present invention, superheated steam refers to a gaseous mixture obtained by heating with an electric heater. For example, when the feed gas phase is hydrogen and the feed liquid phase is pyridine, the superheated steam is a gaseous mixture of hydrogen and pyridine.

[0040] In the present invention, the axial direction refers to the center line direction determined by the length direction of the evaporator itself. The non-parallel arrangement means that the axial direction of the gas distribution pipe forms a certain angle with the axial direction of the evaporator.

[0041] The present invention does not particularly limit the angle between the gas distribution pipe and the axial direction of the evaporator, as long as it can satisfy the passage of the gas phase. Those skilled in the art can select it according to actual needs. Preferably, the gas distribution pipe is perpendicular to the axial direction of the evaporator.

[0042] Preferably, the distribution unit of the evaporator includes a gas distribution pipe and a support beam for fixing the gas distribution pipe.

[0043] The present invention does not particularly limit the arrangement of the support beam, as long as it can fix the gas distribution pipe without shaking. Those skilled in the art can choose according to actual needs.

[0044] According to the present invention, preferably, along the axial direction of the gas distribution pipe, there is a gap between the gas distribution pipe and the right side tube wall of the evaporator for liquid phase circulation.

[0045] According to the present invention, preferably, the gas phase stream is introduced from the gas phase inlet N4.

[0046] The present invention has a wide range of selection for the diameter of the gas distribution pipe. In order to further meet the required flow rate of the gas phase logistics, preferably, the diameter of the gas distribution pipe is 0.1-0.8m, more preferably 0.18-0.5m.

[0047] The present invention does not particularly limit the distance between the gas distribution pipe and the bottom of the evaporator, as long as the gas phase logistics can fully enter the heating unit. Those skilled in the art can make a choice according to actual needs. Preferably, the distance between the gas distribution pipe and the bottom of the evaporator is 0.05-0.6m, more preferably 0.1-0.4m.

[0048] The present invention has a wide range of selection for the number of groups of through holes on the circumferential direction of the tube wall of the gas distribution tube. In order to further enable the gas phase to be evenly distributed in a sufficiently short time, preferably, n groups of through holes are provided along the circumference of the tube wall of the gas distribution tube, and each group independently includes m through holes arranged along the axial direction, n≥3, m≥3, for example, it can be n=3, m=3, n=3, m=4, n=3, m=5, n=4, m=5, n=3, m=8, n=4, m=10, n=4, and any value in the range of any two combinations of n and m; two adjacent groups of through holes are preferably staggered.

[0049] According to the present invention, preferably, Figure 4 As shown, no through hole is provided on the pipe wall above the horizontal plane where the axis of the gas distribution pipe is located (excluding the horizontal plane). It should be noted that in the present invention, the position of the through hole refers to the position of the center of the through hole (if it is a circular through hole, it is the center of the circle).

[0050] The present invention has a wide range of selection for the diameter of the through hole. In order to further enable the gas phase to be evenly distributed in a sufficiently short time, preferably, the diameter of the through hole is 6-30 mm, more preferably 8-18 mm.

[0051] The aperture of the through hole in the present invention is within the above preferred range, which is more conducive to the uniform distribution of gas phase flow.

[0052] The present invention has a wide range for selecting the number of through holes. In order to further enable the gas phase to be evenly distributed in a sufficiently short time, preferably, the number of the through holes is 9-50, and more preferably 20-45.

[0053] In the present invention, the number of through holes is within the above preferred range, which is more conducive to enhancing the dispersion effect of the gas phase flow.

[0054] The present invention has a wide range of selection for the spacing between any two adjacent through holes along the axial direction of the gas distribution pipe. In order to further enable the gas phase to be evenly distributed in a sufficiently short time, preferably, the spacing between any two adjacent through holes along the axial direction of the gas distribution pipe is 10-36mm, more preferably 15-30mm.

[0055] It should be noted that the spacing between two adjacent through holes in the present invention refers to the distance between the centers of the two holes.

[0056] The preferred range of the distance between two adjacent holes in the through-holes of the present invention is more conducive to uniform distribution of gaseous flow, so that the flow is in a completely vaporized state before entering the hydrogenation reactor.

[0057] The present invention has a wide range of selection for the diameter ratio of the axial length of the evaporator and the gas distribution pipe. In order to further enable the gas phase to be evenly distributed in a sufficiently short time, preferably, the diameter ratio of the axial length of the evaporator and the gas distribution pipe is 1:0.5-0.9, for example, it can be 1:0.5, 1:0.55, 1:0.6, 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9 and any value in the range of any two combinations, more preferably 1:0.6-0.9.

[0058] The present invention does not particularly limit the shape of the through hole, as long as the gas phase can be evenly distributed in a sufficiently short time. Those skilled in the art can choose according to actual needs. Preferably, the shape of the through hole is selected from at least one of a circular hole, a triangular hole, a square hole, a polygonal hole, an elliptical hole, and a diamond hole, and a circular hole is more preferred.

[0059] The gas distribution pipe of the present invention has a wide range of settings. The preferred embodiments do not limit the scope of the present invention, but are only used to explain the solutions in the embodiments of the present invention. Those skilled in the art can choose according to actual needs. According to a preferred embodiment of the present invention, Figure 4As shown, the axial length-to-diameter ratio of the evaporator and the gas distribution pipe is 1:0.6-0.9. The gas distribution pipe includes three groups of through holes, totaling 20-45 through holes. Each group of through holes includes at least three through holes arranged axially, and each group of through holes is independent of each other. Two groups of through holes are symmetrically arranged on the pipe wall on a horizontal plane where the axis of the gas distribution pipe lies, while the other group of through holes is arranged on the pipe wall below this horizontal plane and staggered with the two groups of through holes above. Specifically, when viewed from above, the through holes below the horizontal plane are located between two adjacent through holes on the horizontal plane. This is more conducive to extending the residence time of the gas phase in the gas distribution pipe, improving pyridine conversion, piperidine selectivity, and piperidine purity.

[0060] According to the present invention, preferably, the heating unit is arranged 0.1-1.2 m above the gas distribution pipe, more preferably 0.2-0.8 m above the gas distribution pipe.

[0061] The present invention does not particularly limit the number of heat exchange tubes in the heating unit, as long as sufficient vaporization of the gas and liquid phases is achieved. Persons skilled in the art may select a suitable number based on practical needs. Preferably, the heating unit includes at least one set of heat exchange tubes for circulating the heating medium. According to a preferred embodiment of the present invention, the heating unit more preferably comprises two sets of heat exchange tubes (one set comprising 13 heat exchange tubes).

[0062] The present invention does not particularly limit the material, structure, shape and other equipment features of the heat exchange tubes, as long as they can fully vaporize the gas and liquid phase logistics. Those skilled in the art can choose according to actual needs.

[0063] According to the present invention, preferably, the heating medium of the heating unit is water vapor.

[0064] In the present invention, a flange is provided between the heating medium outlet N3 and the gas phase inlet N4 of the evaporator, near the heating medium outlet N3. The shell side is sealed by the flange, so that the logistics enters from the tube side and the heating medium circulates in the shell side.

[0065] According to the present invention, preferably, a heating medium inlet N2 is provided at the upper portion of the evaporator, and a heating medium outlet N3 is provided at the lower portion, so that the heating medium enters the evaporator from the heating medium inlet N2 and flows out from the heating medium outlet N3.

[0066] The present invention does not particularly limit the number of stages of the baffles of the gas-liquid separation tank. As long as the liquid phase logistics can pass through the baffles in sequence and enter the tank to ensure the stability of the liquid level in the gas-liquid separation tank, those skilled in the art can make a choice according to actual needs. Preferably, the gas-liquid separation tank is provided with 1-5 stages of baffles, more preferably 2-4 stages of baffles.

[0067] The present invention does not particularly limit the thickness of the baffle of the gas-liquid separation tank. As long as the liquid phase logistics can pass through the baffle in sequence and enter the tank to ensure the stability of the liquid level in the gas-liquid separation tank, those skilled in the art can choose according to actual needs. Preferably, the thickness of the baffle is 2-10 cm, more preferably 3-8 cm.

[0068] The present invention does not particularly limit the length of the baffle of the gas-liquid separation tank. As long as the liquid phase logistics can pass through the baffle in sequence and enter the tank to ensure the stability of the liquid level in the gas-liquid separation tank, those skilled in the art can choose according to actual needs. Preferably, the length of the baffle is 0.1-0.6m, more preferably 0.2-0.5m.

[0069] The present invention does not particularly limit the bending angle of the baffle of the gas-liquid separation tank. As long as the liquid phase logistics can pass through the baffle in sequence and enter the tank to ensure the stability of the liquid level in the gas-liquid separation tank, those skilled in the art can make a choice according to actual needs. Preferably, the bending angle of the baffle is 10-50°, more preferably 10-30°.

[0070] It should be noted that the bending angle has a conventional definition in this field. The baffle bending angle in the present invention refers to the angle formed by the reverse bending of the end of the baffle toward the flow direction of the logistics, which is used to adjust the flow direction of the fluid.

[0071] The present invention does not particularly limit the distance between the baffle and the liquid phase discharge port N8 at the lower end of the gas-liquid separation tank. As long as the liquid phase logistics can pass through the baffle in sequence and enter the tank to ensure the stability of the liquid level in the gas-liquid separation tank, those skilled in the art can make a choice according to actual needs. Preferably, the distance between the baffle and the liquid phase discharge port N8 at the lower end of the gas-liquid separation tank is 0.6-2m, more preferably 0.8-1.4m.

[0072] It should be noted that the distance between the baffle and the liquid phase discharge port N8 at the lower end of the gas-liquid separation tank in the present invention refers to the vertical distance from the bottom of the last baffle to the liquid phase discharge port.

[0073] The present invention is more conducive to ensuring the stability of the liquid level in the gas-liquid separation tank by setting the baffle parameters within the preferred range. The stable liquid level is conducive to the accurate measurement of the on-site liquid level meter and will not cause the liquid to be re-entrained by the gas phase due to liquid level fluctuations. The baffle acts as a physical barrier in the gas-liquid separation tank. When the gas-liquid mixture enters the gas-liquid separation tank, it first hits the baffle. The baffle changes the flow direction of the gas-liquid mixture, causing the liquid phase to flow downward along the baffle surface under the action of gravity, while the gas phase bypasses the baffle and flows upward, which is more conducive to achieving the initial separation of gas and liquid.

[0074] The present invention does not particularly limit the structure of the baffle of the gas-liquid separation tank. As long as the liquid phase flow can pass through the baffle in sequence and enter the tank to ensure the stability of the liquid level in the gas-liquid separation tank, those skilled in the art can make a choice according to actual needs. Preferably, the surface structure of the baffle is serrated.

[0075] It should be noted that, according to a specific embodiment of the present invention, preferably, the specific arrangement of the saw teeth on the baffle of the present invention is that the saw teeth on the baffle are arranged in a dense shape, each saw tooth is small in size, and there is a uniform interval between adjacent saw teeth.

[0076] The present invention does not particularly limit the tooth height of the saw teeth of the gas-liquid separation tank baffle. As long as the liquid phase logistics can pass through the baffle into the tank in sequence and ensure the stability of the liquid level in the gas-liquid separation tank, technical personnel in this field can make a selection according to actual needs. Preferably, the tooth height of the saw teeth is 1-5 cm, more preferably 1-3 cm.

[0077] In the present invention, the tooth height within the preferred range is more conducive to forming a more tortuous flow path for the liquid phase on the serrations, prolonging the residence time of the liquid phase on the baffle, and allowing small droplets in the liquid phase more time to disperse into a thin layer.

[0078] It should be noted that the tooth height of the saw teeth of the baffle in the present invention is the vertical distance from the bottom of the saw teeth (that is, the part connected to the baffle body) to the top of the saw teeth.

[0079] The present invention does not particularly limit the pitch of the saw teeth of the gas-liquid separation tank baffle. As long as the liquid phase logistics can pass through the baffle into the tank in sequence and ensure the stability of the liquid level in the gas-liquid separation tank, those skilled in the art can make a selection according to actual needs. Preferably, the pitch of the saw teeth is 1-5 cm, more preferably 1-3 cm.

[0080] In the present invention, the tooth pitch within the preferred range is more conducive to evenly distributing the liquid phase between the teeth, avoiding local accumulation of the liquid phase, while also ensuring that the gas phase has a suitable channel to pass smoothly, reducing the interference of the gas phase on the liquid phase.

[0081] It should be noted that the pitch of the baffle teeth in the present invention refers to the distance between the same points on two adjacent teeth. If each tooth is considered an independent geometric shape (such as a triangle), the pitch is the distance from a specific point on one tooth (such as the tip or valley) to the corresponding point on the adjacent tooth.

[0082] According to the present invention, preferably, the gas-liquid separation tank is provided with an on-site liquid level meter L1 and an on-site liquid level meter L2.

[0083] The present invention does not particularly limit the type of on-site liquid level meter, as long as it can achieve the purpose of testing the liquid level, and those skilled in the art can choose it according to actual needs.

[0084] The present invention does not specifically limit the height difference between the on-site liquid level gauge L1 and the on-site liquid level gauge L2. As long as the two liquid level gauges can accurately measure the liquid level heights at different positions in the gas-liquid separation tank, those skilled in the art can make a selection according to actual needs. Preferably, the height difference between the on-site liquid level gauge L1 and the on-site liquid level gauge L2 is 0.4-1.4m, preferably 0.6-1.2m.

[0085] In the present invention, the on-site liquid level gauge L1 is located above the on-site liquid level gauge L2. The on-site liquid level gauge L1 is located between the inlet N7 of the gas-liquid separation tank and the hand hole H.

[0086] According to the present invention, preferably, the gas-liquid separation tank is provided with an on-site pressure gauge P.

[0087] The present invention does not particularly limit the type of on-site pressure gauge, as long as it can accurately measure the pressure in the gas-liquid separation tank. Those skilled in the art can select it according to actual needs.

[0088] The present invention does not particularly limit the distance at which the on-site pressure gauge is set above the gas-liquid separation tank inlet N7. As long as the pressure inside the gas-liquid separation tank can be accurately measured, those skilled in the art can make a selection according to actual needs. Preferably, the on-site pressure gauge P is set 0.3-1.8m above the gas-liquid separation tank inlet N7, and more preferably 0.5-1.4m.

[0089] According to the present invention, preferably, the gas-liquid separation tank is provided with an on-site thermometer T.

[0090] The present invention does not particularly limit the type of on-site thermometer, as long as it can accurately measure the temperature in the gas-liquid separation tank, and those skilled in the art can select it according to actual needs.

[0091] The present invention does not particularly limit the distance at which the field thermometer T is set above the field liquid level gauge L1. As long as the temperature in the gas-liquid separation tank can be accurately measured, those skilled in the art can make a selection according to actual needs. Preferably, the field thermometer T is set 0.5-2m above the field liquid level gauge L1, and more preferably 0.8-1.6m.

[0092] According to the present invention, preferably, the gas-liquid separation tank is provided with a hand hole H.

[0093] It should be noted that the provision of a hand hole in the present invention facilitates operators to operate the equipment.

[0094] The present invention has no special limitation on the distance at which the hand hole H is set below the gas-liquid separation tank inlet N7, as long as it can meet the operator's operation needs. Those skilled in the art can choose according to actual needs. Preferably, the hand hole H is set 0.8-2.5m below the gas-liquid separation tank inlet N7, more preferably 1-2m.

[0095] A second aspect of the present invention provides a method for performing complete gas-liquid two-phase vaporization using the evaporation device described in the first aspect, wherein the method comprises:

[0096] (1) The gaseous raw material is introduced from the gas phase inlet N4, and the liquid phase raw material is introduced from the liquid phase inlet N5 at the bottom of the evaporator, so that the gaseous raw material passes through the gas distribution pipe, mixes with the liquid phase raw material, and enters the heating unit for the first heating;

[0097] (2) sending the heated logistics in step (1) into a gas-liquid separation tank for gas-liquid separation;

[0098] (3) The gas phase logistics obtained by gas-liquid separation is sent to an electric heater for secondary heating.

[0099] The present invention does not particularly limit the heating conditions in step (1), as long as the gas phase and liquid phase logistics can be fully vaporized. Those skilled in the art can select according to actual needs. Preferably, the first heating conditions in step (1) include: a temperature of 100-180°C, more preferably 100-150°C; a pressure of 1-5MPa, more preferably 1.5-4MPa.

[0100] According to the present invention, preferably, the first heating in step (1) comprises: contacting the gaseous raw material and the liquid raw material with a heating medium, preferably, the heating medium is water vapor.

[0101] According to the present invention, preferably, the flow rate of the heating medium is adjusted according to the temperature of the on-site thermometer T.

[0102] According to the present invention, preferably, the treatment method further comprises step (4): returning the liquid phase stream obtained by gas-liquid separation to the evaporator.

[0103] The present invention does not particularly limit the conditions for the second heating in step (3), as long as the gas phase and liquid phase logistics can be heated to superheated steam. Those skilled in the art can select according to actual needs. Preferably, the conditions for the second heating in step (3) include: a temperature of 100-200°C, more preferably 130-180°C; a pressure of 1-5MPa, more preferably 1.5-4MPa.

[0104] The third aspect of the present invention provides the use of the evaporation device described in the first aspect or the treatment method described in the second aspect in a gas-liquid two-phase complete vaporization process, preferably in the mixed vaporization of pyridine and hydrogen.

[0105] A fourth aspect of the present invention provides a method for improving the conversion rate and selectivity of pyridine hydrogenation, wherein the method comprises:

[0106] contacting a gaseous mixture of pyridine and hydrogen with a catalyst under pyridine hydrogenation conditions;

[0107] Wherein, the gas phase mixture is obtained by the processing method described in the second aspect above.

[0108] The present invention does not particularly limit the type of catalyst, as long as it can effectively catalyze the reaction of pyridine and hydrogen. Those skilled in the art can select the catalyst according to actual needs.

[0109] According to the present invention, preferably, the molar ratio of hydrogen to pyridine is 8-40:1, preferably 10-30:1.

[0110] According to the present invention, preferably, the hydrogenation conditions are: temperature 100-200°C, more preferably 120-180°C; pressure 1-5 MPa, more preferably 1.0-4.0 MPa; pyridine mass space velocity 0.1-4h -1 , preferably 0.1-2h -1 .

[0111] It should be noted that the pyridine mass space velocity in the present invention refers to the liquid phase feed mass flow rate of pyridine / catalyst loading mass.

[0112] The following combination Figure 1 、 Figure 2 、 Figure 3 and Figure 4 The evaporation device and the gas-liquid two-phase complete vaporization processing method of the present invention are described in detail:

[0113] According to some specific embodiments of the present invention, the heating medium is low-pressure water vapor, which flows into the heating medium inlet N2 of the evaporator, and after the heating unit inside the evaporator exerts its heating effect, it flows out from the heating medium outlet N3 in the form of steam condensate, thereby achieving the purpose of circulating heating. The gas phase logistics passes through the gas phase inlet N4 of the evaporator. The evenly distributed through holes on the distribution pipe can ensure that the gas phase logistics is evenly distributed in a very short time. The liquid phase logistics enters the evaporator through the liquid phase inlet N5 at the bottom of the evaporator, and mixes with hydrogen through the gap between the gas distribution pipe and the evaporator. The gas phase logistics and the liquid phase logistics form a gas-liquid mixture in the evaporator heating unit, flow out from the outlet N1 at the top of the evaporator, and then enter the gas-liquid separation tank through the gas-liquid separation tank inlet N7. The gas-liquid separation tank is provided with multiple baffles inside, so that the liquid phase flows into the tank through the baffles in sequence, effectively maintaining the stability of the liquid level in the tank. The liquid phase flow in the gas-liquid separation tank is discharged from the liquid phase outlet N8 at the lower end of the gas-liquid separation tank, and flows back to the evaporator through the liquid phase inlet N5 at the bottom of the evaporator. The gas phase enters the electric heater from the gas phase outlet N6 of the gas-liquid separation tank, where it is further heated and converted into superheated steam, and then can smoothly enter the subsequent hydrogenation reaction process.

[0114] The gas outlet of the gas-liquid separator is equipped with a field thermometer T. This temperature measurement port establishes an interlocking mechanism with the evaporator's heating medium, the water vapor flow rate. This allows the evaporator's water vapor flow rate to be adjusted according to the outlet temperature, ensuring the stable operation of the entire system. In addition, the gas-liquid separator is equipped with field level gauges L1 and L2, a field pressure gauge P, a field thermometer T, and a hand port H. These monitoring and operating components provide convenience and assurance for the device's operation monitoring, maintenance, and overhaul.

[0115] The evaporation device of the present invention can realize complete vaporization of liquid phase logistics and has the characteristics of high pyridine conversion rate and piperidine selectivity.

[0116] The present invention will be described in detail below through examples.

[0117] In the following examples and comparative examples, unless otherwise specified, conventional methods are used; the reagents and materials used, unless otherwise specified, are commercially available and / or prepared using methods known in the art.

[0118] In the following examples and comparative examples, The conversion of pyridine was determined by gas chromatography.

[0119] In the following examples and comparative examples, The selectivity of piperidine was determined by gas chromatography.

[0120] Example 1

[0121] Parameters of evaporation device:

[0122] The evaporation device structure used is as follows Figure 1 As shown, the axial length to diameter ratio of the evaporator and the gas distribution pipe is 1:0.88, the gas distribution pipe comprises three groups of through holes, 30 evenly distributed circular holes are provided, each group of through holes comprises 10 through holes arranged along the axial direction, and each group of through holes is independent of each other. Figure 3 Similar to the structure shown, two groups of through holes are symmetrically arranged on the tube wall on the horizontal plane where the axis of the gas distribution pipe is located, and another group of through holes is arranged on the tube wall below the horizontal plane, and is staggered with the two groups of through holes above. Specifically, when viewed from above, the through holes below the horizontal plane are located between two adjacent through holes on the horizontal plane. The aperture of the through hole is 12 mm, and the distance between any two adjacent through holes along the axial direction of the gas distribution pipe is 20 mm. The diameter of the gas distribution pipe is 0.25 m, and the distance between the gas distribution pipe and the bottom of the evaporator is 0.3 m. The heating unit is set 0.4 m above the gas distribution pipe. The heating unit includes two groups of heat exchange tubes, and the heating medium is water vapor.

[0123] The structure of the gas-liquid separation tank is as follows Figure 4 As shown, the gas-liquid separation tank is provided with three-level baffles, the thickness of the baffle is 4 cm, the length of the baffle is 0.2 m, the bending angle of the baffle is 30°, the distance between the baffle and the liquid phase discharge port N8 at the lower end of the gas-liquid separation tank is 1.2 m, the surface structure of the baffle is serrated, the tooth height of the sawtooth is 1.5 cm, the tooth pitch of the sawtooth is 1.5 cm, the height difference between the on-site liquid level gauge L1 and the on-site liquid level gauge L2 is 1 m, the on-site pressure gauge P is set 0.8 m above the gas-liquid separation tank inlet N7, the on-site thermometer T is set 1.3 m above the on-site liquid level gauge L1, and the hand hole H is set 1.4 m below the gas-liquid separation tank inlet N7.

[0124] According to the present method, the molar ratio of pyridine (purity 99.9%) to hydrogen is 1:10, the pyridine is preheated to 100°C, the preheated pyridine and hydrogen enter the evaporator at a temperature of 140°C and a pressure of 3 MPa, the gas-liquid mixture enters the pyridine gas-liquid separation tank for separation, and the gaseous phase enters the electric heater at a temperature of 150°C and a pressure of 3 MPa to completely vaporize the pyridine. The vaporized pyridine and hydrogen flow through a tubular fixed-bed reactor equipped with a catalyst (based on the total amount of the catalyst, the palladium content is 1.0 wt%, the ruthenium content is 0.8 wt%, and the content of the carrier alumina is 98.2 wt%), and the reaction temperature is controlled at 150°C, the reaction pressure is 3 MPa, and the pyridine mass space velocity is 0.6 h -1 The products were separated by gas-liquid separation tank and the liquid products at the lower end were collected for analysis. The conversion rate of pyridine was 99.99%, the selectivity of piperidine was 99.7%, and the reactor could operate continuously for more than 1200 hours.

[0125] Example 2

[0126] The evaporation device structure used is as follows Figure 1 As shown, the axial length to diameter ratio of the evaporator and the gas distribution pipe is 1:0.7, the gas distribution pipe comprises three groups of through holes, with 45 evenly distributed circular holes, each group of through holes comprises 15 through holes arranged along the axial direction, and each group of through holes is independent of each other. Figure 4 Similar to the structure shown, two sets of through holes are symmetrically arranged on the tube wall above the horizontal plane of the gas distribution tube axis, while another set of through holes is arranged below this horizontal plane and staggered with the two sets of through holes above. Specifically, when viewed from above, the through holes below the horizontal plane are located between two adjacent through holes on the horizontal plane. The through hole diameter is 10 mm, and the spacing between any two adjacent through holes along the axial direction of the gas distribution tube is 15 mm. The gas distribution tube has a diameter of 0.25 m, and the distance between the gas distribution tube and the bottom of the evaporator is 0.3 m. The heating unit is located 0.4 m above the gas distribution tube. The heating unit comprises two sets of heat exchange tubes, and the heating medium is water vapor.

[0127] The structure of the gas-liquid separation tank is as follows Figure 4 As shown, it is the same as in Example 1.

[0128] According to the present method, the molar ratio of pyridine (purity 99.9%) to hydrogen is 1:10. The pyridine is preheated to 100° C. The preheated pyridine and hydrogen enter an evaporator at a temperature of 140° C. and a pressure of 2 MPa. The gas-liquid mixture enters a pyridine gas-liquid separation tank for separation, and the gaseous phase enters an electric heater at a temperature of 140° C. and a pressure of 2 MPa to completely vaporize the pyridine. The vaporized pyridine and hydrogen flow through a tubular fixed-bed reactor equipped with a catalyst (based on the total amount of the catalyst, the palladium content is 1.0 wt%, the ruthenium content is 0.8 wt%, and the content of the carrier alumina is 98.2 wt%). The reaction temperature is controlled at 143° C., the reaction pressure is 2 MPa, and the pyridine mass space velocity is 1.5 h -1 , separated by a gas-liquid separator, and the liquid product at the lower end was collected for analysis. The conversion rate of pyridine was 99.99%, the selectivity of piperidine was 99.65%, and the reactor could operate continuously for more than 1200 hours.

[0129] Example 3

[0130] The parameters of the evaporation device are the same as those in Example 1.

[0131] According to the present method, the molar ratio of pyridine (purity 99.9%) to hydrogen is 1:10. The pyridine is preheated to 100° C. The preheated pyridine and hydrogen enter an evaporator at a temperature of 150° C. and a pressure of 3.5 MPa. The gas-liquid mixture enters a pyridine gas-liquid separation tank for separation, and the gaseous phase enters an electric heater at a temperature of 155° C. and a pressure of 3.5 MPa to completely vaporize the pyridine. The vaporized pyridine and hydrogen flow through a tubular fixed-bed reactor equipped with a catalyst (based on the total amount of the catalyst, the palladium content is 1.0 wt%, the ruthenium content is 0.8 wt%, and the content of the carrier alumina is 98.2 wt%). The reaction temperature is controlled at 165° C., the reaction pressure is 3.5 MPa, and the pyridine mass space velocity is 0.3 h -1 , separated by a gas-liquid separator, and the liquid product at the lower end was collected for analysis. The conversion rate of pyridine was 99.99%, the selectivity of piperidine was 99.58%, and the reactor could operate continuously for more than 1200 hours.

[0132] Example 4

[0133] The method and evaporation apparatus parameters of Example 1 were followed, except that the gas distribution tube had 21 through-holes, each group of which consisted of 7 axially arranged through-holes with a diameter of 20 mm. The spacing between any two adjacent axially aligned through-holes in the gas distribution tube was 30 mm. The pyridine conversion rate was 99.9%, the piperidine selectivity was 98.8%, and the reactor operated continuously for over 800 hours.

[0134] Example 5

[0135] The method and evaporation apparatus parameters of Example 1 were followed, except that the separator was equipped with a single baffle, which had a thickness of 4 cm, a length of 0.4 m, a bending angle of 30°, and a distance of 1.4 m from the liquid phase outlet N8 at the lower end of the separator. The pyridine conversion rate was 99.9%, the piperidine selectivity was 99%, and the reactor could operate continuously for over 1000 hours.

[0136] Comparative Example 1

[0137] The method of Example 1 was followed, except that the preheated pyridine and hydrogen were directly mixed in a mixer, and the mixed pyridine and hydrogen were heated to 160° C. in an electric heater, followed by a hydrogenation reaction. The pyridine conversion rate was 98%, the piperidine selectivity was 95%, and the pyridine conversion rate decreased after the catalyst was operated for 100 h.

[0138] Comparative Example 2

[0139] According to the method and parameters of the evaporation device of Example 1, except that no gas distribution pipe is provided in the evaporator, the conversion rate of pyridine is 99%, the selectivity of piperidine is 97%, and the reactor can operate continuously for about 500 hours.

[0140] The above results show that, compared with the comparative example, the piperidine selectivity of the embodiment using the evaporation apparatus provided by the present invention is improved, the degree of catalyst deactivation is reduced, and the operating time of the reactor is increased, indicating that pyridine and hydrogen can be completely vaporized. After the pyridine is completely vaporized, it can enter the hydrogenation reactor and fully contact the catalyst, thus solving the problem that the liquid phase stream cannot be completely vaporized before entering the reactor.

[0141] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. An evaporation device, characterized in that: The device comprises an evaporator, a gas-liquid separation tank and an electric heater connected in sequence; From bottom to top along the axial direction of the evaporator, the evaporator includes a distribution unit and a heating unit in sequence. The distribution unit includes a gas distribution pipe arranged non-parallel to the axial direction of the evaporator. The pipe wall of the gas distribution pipe is provided with a through hole. One end of the gas distribution pipe is provided with a gas phase inlet. The bottom of the evaporator is provided with a liquid phase inlet, so that the gas phase passes through the gas distribution pipe, mixes with the liquid phase, and enters the heating unit; The gas-liquid separation tank is provided with a baffle; The electric heater is connected to the gas phase outlet of the gas-liquid separation tank and is used to heat the gas phase flow from the gas-liquid separation tank into superheated steam.

2. The evaporation device according to claim 1, wherein The distribution unit of the evaporator includes a gas distribution pipe and a support beam for fixing the gas distribution pipe, and the gas distribution pipe is perpendicular to the axial direction of the evaporator; Preferably, along the axial direction of the gas distribution pipe, there is a gap between the gas distribution pipe and the right side wall of the evaporator for liquid phase circulation; Preferably, the gas phase stream is introduced from the gas phase inlet (N4); Preferably, the diameter of the gas distribution pipe is 0.1-0.8m; Preferably, the distance between the gas distribution pipe and the bottom of the evaporator is 0.05-0.6m; Preferably, n groups of through holes are provided along the circumference of the wall of the gas distribution pipe, each group independently including m through holes arranged along the axial direction, n≥3, m≥3; two adjacent groups of through holes are preferably staggered; Preferably, no through-hole is provided on the pipe wall above the horizontal plane where the axis of the gas distribution pipe is located; Preferably, the through hole has a diameter of 6-30 mm, preferably 8-18 mm; Preferably, the number of the through holes is 9-50, preferably 20-45; Preferably, the distance between any two adjacent through holes along the axial direction of the gas distribution pipe is 10-36 mm, preferably 15-30 mm; and / or, the axial length to diameter ratio of the evaporator and the gas distribution pipe is 1:0.5-0.9; Preferably, the shape of the through hole is selected from at least one of a circular hole, a triangular hole, a square hole, a polygonal hole, an elliptical hole, and a diamond hole, and is preferably a circular hole.

3. The evaporation device according to claim 1 or 2, wherein: The heating unit is arranged 0.1-1.2m above the gas distribution pipe; Preferably, the heating unit comprises at least one set of heat exchange tubes for circulating the heating medium; Preferably, the heating medium of the heating unit is water vapor; Preferably, the evaporator is provided with a heating medium inlet (N2) at the top and a heating medium outlet (N3) at the bottom, so that the heating medium enters the evaporator from the heating medium inlet (N2) and flows out from the heating medium outlet (N3).

4. The evaporation device according to any one of claims 1 to 3, wherein: The gas-liquid separation tank is provided with 1-5 levels of baffles, preferably 2-4 levels of baffles; Preferably, the thickness of the baffle is 2-10 cm, preferably 3-8 cm; Preferably, the length of the baffle is 0.1-0.6 m, preferably 0.2-0.5 m; Preferably, the baffle has a bending angle of 10-50°, preferably 10-30°; Preferably, the distance between the baffle and the liquid phase discharge port (N8) at the lower end of the gas-liquid separation tank is 0.6-2m, preferably 0.8-1.4m; Preferably, the surface structure of the baffle is serrated; Preferably, the saw teeth have a tooth height of 1-5 cm, preferably 1-3 cm; Preferably, the tooth pitch of the saw teeth is 1-5 cm, preferably 1-3 cm; And / or, the gas-liquid separation tank is provided with an on-site liquid level meter (L1) and an on-site liquid level meter (L2); Preferably, the height difference between the on-site liquid level gauge (L1) and the on-site liquid level gauge (L2) is 0.4-1.4 m, preferably 0.6-1.2 m; And / or, the gas-liquid separation tank is provided with an on-site pressure gauge (P); Preferably, the on-site pressure gauge (P) is arranged 0.3-1.8 m above the gas-liquid separation tank inlet (N7), preferably 0.5-1.4 m; And / or, the gas-liquid separation tank is provided with an on-site thermometer (T); Preferably, the on-site thermometer (T) is arranged 0.5-2m above the on-site liquid level meter (L1), preferably 0.8-1.6m; And / or, the gas-liquid separation tank is provided with a hand hole (H); Preferably, the hand hole (H) is arranged 0.8-2.5m below the gas-liquid separation tank inlet (N7), preferably 1-2m.

5. A method for completely vaporizing gas-liquid two-phase using the evaporation device according to any one of claims 1 to 4, characterized in that: The method includes: (1) The gaseous raw material is introduced from the gas phase inlet (N4), and the liquid phase raw material is introduced from the liquid phase inlet (N5) at the bottom of the evaporator, so that the gaseous raw material passes through the gas distribution pipe, mixes with the liquid phase raw material, and enters the heating unit for the first heating; (2) sending the heated logistics in step (1) into a gas-liquid separation tank for gas-liquid separation; (3) The gas phase logistics obtained by gas-liquid separation is sent to an electric heater for secondary heating.

6. The processing method according to claim 5, wherein: The first heating conditions in step (1) include: a temperature of 100-180° C., preferably 100-150° C.; a pressure of 1-5 MPa, preferably 1.5-4 MPa; And / or, in step (1), the first heating comprises: contacting the gaseous raw material and the liquid raw material with a heating medium, preferably, the heating medium is water vapor; Preferably, the flow rate of the heating medium is adjusted according to the temperature of the on-site thermometer (T).

7. The processing method according to claim 5 or 6, wherein: The treatment method further comprises the step (4): returning the liquid phase stream obtained by gas-liquid separation to the evaporator; And / or, the second heating conditions in step (3) include: temperature of 100-200° C., preferably 130-180° C.; pressure of 1-5 MPa, preferably 1.5-4 MPa.

8. Use of the evaporation device according to any one of claims 1 to 4 or the treatment method according to any one of claims 5 to 7 in a gas-liquid two-phase complete vaporization process, preferably in the mixed vaporization of pyridine and hydrogen.

9. A method for improving the conversion rate and selectivity of pyridine hydrogenation, characterized in that: The method includes: contacting a gaseous mixture of pyridine and hydrogen with a catalyst under pyridine hydrogenation conditions; Wherein, the gas phase mixture is obtained by the treatment method according to any one of claims 5 to 7.

10. The method according to claim 9, wherein: The molar ratio of hydrogen to pyridine is 8-40:1, preferably 10-30:1; And / or, the hydrogenation conditions are: temperature 100-200°C, preferably 120-180°C; pressure 1-5 MPa, preferably 1.0-4.0 MPa; pyridine mass space velocity 0.1-4h -1 , preferably 0.1-2h -1 .

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