A pre-evaporator for low-temperature hydrogenation refining process of coking crude benzene

Abstract

The present invention relates to a pre-evaporator for a low-temperature hydrofining process of coking crude benzene, comprising a lower tube box, a heat exchange device and an upper tube box, characterized in that the lower tube box, the heat exchange device and the upper tube box are arranged in sequence from bottom to top, and are fastened by flange connection. The beneficial effect is that the device of the invention adopts an improved vertical fixed tube sheet heat exchanger, which can solve the problem that the tube side is easy to be blocked and the shell side is easy to crystallize ammonium salt due to the excessively fast temperature rise in the heat exchanger when the existing conventional cooler is directly used in the production of the low-temperature hydrofining process of coking crude benzene, and the production process is smooth and the heat exchange efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of benzene hydrogenation refining, in particular to a pre-evaporator for a low-temperature hydrogenation refining process of coking crude benzene. Background Art

[0002] The low-temperature hydrorefining process of coking crude benzene is a process in which the gaseous raw materials are converted into hydrocarbons, hydrogen sulfide, water and ammonia under the action of a catalyst, and unsaturated olefins undergo a saturation reaction. After the crude benzene is mixed with the circulating hydrogen, it exchanges heat with the reactor outlet product and is partially vaporized. The temperature rise in the heat exchanger is too fast, and the tube side of the heat exchanger is prone to blockage, and ammonium salt crystallization is prone to occur in the shell side. Once blockage or ammonium salt crystallization occurs, the heat exchange efficiency of the heat exchanger is directly reduced, affecting the smooth operation of the low-temperature hydrorefining process of coking crude benzene. This is also the main problem of the current conventional cooler directly used in the production of the low-temperature hydrorefining process of coking crude benzene. Summary of the invention

[0003] In order to overcome the defects of the prior art, the technical problem solved by the present invention is to provide a pre-evaporator for the low-temperature hydrorefining process of coking crude benzene. The improved vertical fixed tube sheet heat exchanger is adopted to solve the problems that the tube side is easily blocked and ammonium salt crystallization is easily generated in the shell side due to the excessively rapid temperature rise in the heat exchanger when the existing conventional cooler is directly used in the production of the low-temperature hydrorefining process of coking crude benzene. The production process is smooth and the heat exchange efficiency is high.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A pre-evaporator for a low-temperature hydrorefining process of coking crude benzene, comprising a lower pipe box, a heat exchange device and an upper pipe box, characterized in that the lower pipe box, the heat exchange device and the upper pipe box are arranged in sequence from bottom to top, and are fastened by flange connection between the two;

[0006] The heat exchange device is composed of a tube sheet, a heat exchange cylinder, a cone section, a support plate, a straight section, a heat exchange tube, a distance tube, a tie rod and a flow guide cylinder, wherein the heat exchange cylinder, the flow guide cylinder and the cone section are each two, the two ends of the straight section are respectively welded to the small ends of the two cone sections, the large ends of the two cone sections are respectively welded to the heat exchange cylinder, the other end of the heat exchange cylinder is respectively welded to the tube sheet, and the two flow guide cylinders are respectively arranged in the heat exchange cylinder and the cone section; the support plates are N pieces, which are supported by the distance tubes and arranged in order with equal distances from bottom to top The lower end of the tie rod is seated on the tube sheet at the lower end and passes through the spacing tube and the support plate in sequence, and is fastened to the uppermost support plate with threads; the heat exchange tube is a plurality of heat exchange tube holes passing through the support plate, the lower end is fixedly connected to the tube sheet and extends out of the tube sheet to communicate with the lower tube box, and the upper end is fixedly connected to the tube sheet and extends out of the tube sheet to communicate with the upper tube box; the heat exchange cylinder at the lower end of the heat exchange device is provided with a reactor product inlet and a venting port, and the heat exchange cylinder at the upper end of the heat exchange device is provided with a reactor product outlet and a venting port;

[0007] The upper tube box is composed of a head, an upper cylinder, an upper cone section and a lower cylinder, wherein the head, the upper cylinder and the large ends of the upper cone section are welded and connected in sequence, and the small end of the upper cone section is welded and connected to the lower cylinder; the upper part of the upper cylinder is provided with a crude benzene hydrogen inlet, and the lower part is provided with a crude benzene hydrogen outlet, wherein the crude benzene hydrogen outlet is an L-shaped tubular structure extending into the upper tube box, with an open upper end and a through hole on the lower tube body; the head is provided with a venting port;

[0008] The lower tube box is provided with a crude benzene outlet on the side and a vent at the bottom;

[0009] The crude benzene outlet and the crude benzene hydrogen inlet are connected through an ejector device.

[0010] The product inlet of the reactor, the heat exchange cylinder, the cone section and the flow guide cylinder constitute a feed distribution device.

[0011] The support plate is provided with heat exchange tube holes and tie rod holes matching the heat exchange tubes and tie rods, and an injection hole is opened between the heat exchange tube holes and the tie rod holes. The injection hole is in a trumpet shape with the small end at the bottom.

[0012] The inner diameter of the guide cylinder is equal to the inner diameter of the straight section.

[0013] The distance tube is sleeved on the pull rod and arranged between the support plate and the lower tube plate or between two adjacent support plates.

[0014] A support is provided on the heat exchange cylinder at the upper end of the heat exchange device.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1) The crude benzene outlet and the crude benzene hydrogen inlet are connected through an ejector device, and the ejector device ejects the crude benzene in the crude benzene outlet and the crude benzene hydrogen inlet feed into the upper pipe box together, thereby increasing the liquid circulation volume, avoiding excessive temperature rise of crude benzene, and reducing blockage;

[0017] 2) Conventional heat exchangers use baffles, and the medium passes through the heat exchange tube horizontally, which is prone to ammonium salt crystallization. However, the support plate of this patent has a spray hole in the center of the heat exchange tube hole and the tie rod hole. The small end of the spray hole is at the bottom. During the process of the medium flowing from bottom to top, it enters from the small end of the spray hole and exits from the large end. The medium flow rate is reduced, and the flow direction is sprayed toward the outer heat exchange tube, reducing ammonium salt crystallization;

[0018] 3) The reactor product inlet, cylinder, cone section, and guide cylinder constitute a feed distribution device. The reactor product enters the annular space, flows downward into the bottom space of the heat exchange tube, and flows upward evenly along the heat exchange tube, with high heat exchange efficiency;

[0019] 4) The structure is simple and compact, easy to implement and has high heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structural principle of the present invention;

[0021] Figure 2 It is a schematic diagram of the structural principle of the tube sheet of the present invention;

[0022] Figure 3 It is a schematic diagram of the structural principle of the support plate of the present invention;

[0023] Figure 4 Figure 3 Schematic diagram of the structure principle of the local enlargement of the middle C part;

[0024] Figure 5 yes Figure 4 Schematic diagram of the structural principle in the AA section.

[0025] In the figure: 1-lower tube box 2-tube sheet 3-reactor product inlet 4-heat exchange cylinder 5-cone section 6-support plate 61-injection hole 7-straight section 8-heat exchange tube 81-heat exchange tube hole 9-spacer 10-pull rod 101-pull rod hole 11-flow guide cylinder 12-reactor product outlet 13-upper tube box 14-crude benzene hydrogen outlet 141-through hole 15-crude benzene hydrogen inlet 16-support 17-crude benzene outlet 18-venting port 19-venting port 20-end 21-upper cylinder 22-upper cone section 23-lower cylinder DETAILED DESCRIPTION

[0026] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0027] See Figure 1-Figure 5 As shown, the present invention relates to a pre-evaporator for a low-temperature hydrorefining process of coking crude benzene, comprising a lower pipe box 1, a heat exchange device and an upper pipe box 13, wherein the lower pipe box 1, the heat exchange device and the upper pipe box 13 are arranged in sequence from bottom to top, and are fastened by flange connection between the two;

[0028] The heat exchange device is composed of a tube sheet 2, a heat exchange cylinder 4, a cone section 5, a support plate 6, a straight section 7, a heat exchange tube 8, a distance tube 9, a tie rod 10 and a flow guide cylinder 11, wherein the heat exchange cylinder 4, the flow guide cylinder 11 and the cone section 5 are each two, the two ends of the straight section 7 are respectively welded to the small ends of the two cone sections 5, the large ends of the two cone sections 5 are respectively welded to the heat exchange cylinder 4, the other end of the heat exchange cylinder 4 is respectively welded to the tube sheet 2, and the two flow guide cylinders 11 are respectively arranged in the heat exchange cylinder 4 and the cone section 5; the support plate 6 is N pieces, which are supported by the distance tube 8 and arranged in order at equal distances from bottom to top. The lower end of the tie rod 9 is located on the tube sheet 2 at the lower end and passes through the distance tube 8 and the support plate 6 in sequence and is fastened to the uppermost support plate 6 by threads; the heat exchange tube 8 is a plurality of heat exchange tube holes 81 passing through the support plate 6, the lower end of which is fixedly connected to the tube sheet 2 and extends out of the tube sheet 2 to communicate with the lower tube box 1, and the upper end of which is fixedly connected to the tube sheet 2 and extends out of the tube sheet 2 to communicate with the upper tube box 13; the heat exchange cylinder 4 at the lower end of the heat exchange device is provided with a reactor product inlet 3 and a vent 18, and the heat exchange cylinder 4 at the upper end of the heat exchange device is provided with a reactor product outlet 12 and a vent 19;

[0029] The upper tube box 13 is composed of a head 20, an upper cylinder 21, an upper cone section 22 and a lower cylinder 23, wherein the head 20, the upper cylinder 21 and the large ends of the upper cone section 22 are welded in sequence, and the small end of the upper cone section 22 is welded to the lower cylinder 23; the upper part of the upper cylinder 21 is provided with a crude benzene hydrogen inlet 15, and the lower part is provided with a crude benzene hydrogen outlet 14, wherein the crude benzene hydrogen outlet 14 is an L-shaped tubular structure extending into the upper tube box 13, with an open upper end and a through hole 141 on the lower tube body; the head 20 is provided with a venting port 19;

[0030] The lower tube box 1 is provided with a crude benzene outlet 17 on the side and a vent 18 at the bottom;

[0031] The crude benzene outlet 17 is connected to the crude benzene hydrogen inlet 15 via an ejector.

[0032] The reactor product inlet 3, the heat exchange cylinder 4, the cone section 5 and the flow guide cylinder 11 constitute a feed distribution device.

[0033] The support plate 6 is provided with a heat exchange tube hole 81 and a tie rod hole 101 matching the heat exchange tube 8 and the tie rod 10, and an injection hole 61 is opened between the heat exchange tube hole 81 and the tie rod hole 101. The injection hole 61 is in a trumpet shape with the small end at the bottom.

[0034] The inner diameter of the guide cylinder 11 is equal to the inner diameter of the straight section 7 .

[0035] The distance tube 9 is sleeved on the tie rod 10 and is arranged between the support plate 6 and the tube plate 2 or between two adjacent support plates 6 .

[0036] A support is provided on the heat exchange cylinder 4 at the upper end of the heat exchange device.

[0037] When working, the following steps are included:

[0038] 1) Raw material flow: Crude benzene hydrogen enters the upper tube box 13 from the crude benzene hydrogen inlet 15, and the crude benzene liquid flows downward into the heat exchange tube 8 for heat exchange, flows from top to bottom into the lower tube box 1, and is ejected by the ejector device so that the crude benzene in the crude benzene outlet 17 and the feed of the crude benzene hydrogen inlet 15 enter the upper tube box 13 again, and the reciprocating cycle increases the circulation amount of the crude benzene liquid, avoids the crude benzene temperature rising too fast, and reduces blockage; hydrogen flows upward into the crude benzene hydrogen outlet 14 pipeline, and the heated crude benzene liquid in this process also enters from the through hole 141 and goes to the next stage heat exchanger through the crude benzene hydrogen outlet 14 to continue heating the crude benzene;

[0039] 2) Medium flow: The medium enters from the reactor product inlet 3, flows downward along the guide cylinder 11 into the bottom of the heat exchange tube 8, flows evenly from bottom to top along the outer wall of the heat exchange tube 8, and exchanges heat with the crude benzene liquid in the heat exchange tube 8 before being discharged from the reactor product outlet 12, with high heat exchange efficiency;

[0040] The support plate 6 has an injection hole 61 at the center of the heat exchange tube hole 81 and the pull rod hole 101. The small end of the injection hole 61 is at the bottom. During the flow of the medium from bottom to top, the medium enters from the small end of the injection hole 61 and exits from the large end. The flow velocity of the medium is reduced, and the flow direction is sprayed toward the outer heat exchange tube 8 to reduce the crystallization of ammonium salt.

[0041] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A pre-evaporator for low-temperature hydrorefining of coking crude benzene, comprising a lower tube box, a heat exchange device and an upper tube box, characterized in that: The lower tube box, the heat exchange device and the upper tube box are arranged in sequence from bottom to top, and are fastened by flange connection between each other; The heat exchange device is composed of a tube sheet, a heat exchange cylinder, a cone section, a support plate, a straight section, a heat exchange tube, a distance tube, a tie rod and a flow guide cylinder, wherein the heat exchange cylinder, the flow guide cylinder and the cone section are each two, the two ends of the straight section are respectively welded to the small ends of the two cone sections, the large ends of the two cone sections are respectively welded to the heat exchange cylinder, the other end of the heat exchange cylinder is respectively welded to the tube sheet, and the two flow guide cylinders are respectively arranged in the heat exchange cylinder and the cone section; the support plates are N pieces, which are supported by the distance tubes and arranged in order with equal distances from bottom to top The lower end of the tie rod is seated on the tube sheet at the lower end and passes through the spacing tube and the support plate in sequence, and is fastened to the uppermost support plate with threads; the heat exchange tube is a plurality of heat exchange tube holes passing through the support plate, the lower end is fixedly connected to the tube sheet and extends out of the tube sheet to communicate with the lower tube box, and the upper end is fixedly connected to the tube sheet and extends out of the tube sheet to communicate with the upper tube box; the heat exchange cylinder at the lower end of the heat exchange device is provided with a reactor product inlet and a venting port, and the heat exchange cylinder at the upper end of the heat exchange device is provided with a reactor product outlet and a venting port; The upper tube box is composed of a head, an upper cylinder, an upper cone section and a lower cylinder, wherein the head, the upper cylinder and the large ends of the upper cone section are welded and connected in sequence, and the small end of the upper cone section is welded and connected to the lower cylinder; the upper part of the upper cylinder is provided with a crude benzene hydrogen inlet, and the lower part is provided with a crude benzene hydrogen outlet, wherein the crude benzene hydrogen outlet is an L-shaped tubular structure extending into the upper tube box, with an open upper end and a through hole on the lower tube body; the head is provided with a venting port; The lower tube box is provided with a crude benzene outlet on the side and a vent at the bottom; The crude benzene outlet and the crude benzene hydrogen inlet are connected via an ejector; The reactor product inlet, heat exchange cylinder, cone section and flow guide cylinder constitute a feed distribution device; The support plate is provided with heat exchange tube holes and tie rod holes matching the heat exchange tubes and tie rods, and an injection hole is opened between the heat exchange tube holes and the tie rod holes. The injection hole is in a trumpet shape with the small end at the bottom.

2. The pre-evaporator for low-temperature hydrorefining of coking crude benzene according to claim 1, characterized in that: The inner diameter of the guide cylinder is equal to the inner diameter of the straight section.

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