CN112915925B

CN112915925B - Venturi type gas-liquid distributor

Info

Publication number: CN112915925B
Application number: CN202110261475.6A
Authority: CN
Inventors: 李浩铎; 刘辉
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2021-03-10
Filing date: 2021-03-10
Publication date: 2022-11-15
Anticipated expiration: 2041-03-10
Also published as: CN112915925A

Abstract

The invention discloses a Venturi type gas-liquid distributor, which belongs to the technical field of petroleum refining and petrochemical industry and comprises a tubular shell with two closed ends, a reducer pipe arranged in the tubular shell and a Venturi tube arranged at the bottom of the tubular shell, wherein a gas phase inlet is an obliquely upward notch positioned on the side surface of the top of the tubular shell, a liquid phase inlet is 4 waist holes vertically arranged in the length direction of the tubular shell, and gas and liquid phases are fully mixed in the Venturi tube and uniformly distributed on a catalyst bed layer after entering from the inlet. The invention is mainly used for hydrogenation reactors in petroleum refining and chemical industry, can effectively improve the fluid flowing state in the fixed bed reactor, effectively overcomes the problem that part of catalysts cannot be completely wetted or excessively used due to channeling formed by uneven distribution, and ensures the product quality and the device safety.

Description

Venturi type gas-liquid distributor

Technical Field

The invention relates to a Venturi type gas-liquid distributor, and belongs to the technical field of petroleum refining and petrochemical industry.

Background

The gas-liquid distributor is an important internal component of the hydrogenation reactor, and a plurality of gas-liquid distributors are arranged on the tray plate according to a certain rule to form a gas-liquid distribution tray. Each gas-liquid distributor is a distribution unit, gas-liquid materials are mixed in the distributor and sprayed on the surface of the catalyst, and the gas-liquid materials are uniformly distributed in the catalyst bed layer, so that gas, liquid and solid phases are fully contacted, and the performance of the catalyst is exerted to the maximum extent. If the distributor performance is low, the material distribution is uneven, and the catalyst forming the channeling part can not be completely wetted or be excessively used, the waste and local overheating of the catalyst can be caused, and the product quality and even the device safety can be directly influenced.

Due to the important function of the gas-liquid distributor, many scholars and institutions at home and abroad put great efforts, and various gas-liquid distributors with different structures are provided, and the gas-liquid distributors can be divided into overflow type, suction type and mixed type according to the mode that a liquid phase enters the gas-liquid distributor.

The united states patent US3524731 discloses a long and short pipe gas-liquid distributor which belongs to an overflow type distributor, and is composed of long and short pipes, liquid phase materials are gradually accumulated on a tray, when the height of the short pipe is higher than the liquid level, the materials overflow into a bed layer from the short pipe, and gas phase enters into the bed layer through the long pipe. The distributor can approximately realize the uniform distribution of materials by reasonably arranging the positions of the long and short pipes, but has the phenomenon of central convergence, smaller operation elasticity and more rigorous requirement on installation levelness.

Chinese patent CN2757911Y discloses a suction split-flow type gas-liquid distributor, which adds a split-flow pipe on the basis of the traditional suction type distributor structure, reduces the pressure drop of the distributor and partially improves the gas-liquid distribution effect, but the dispersion area of the distributor to the gas-liquid mixture flow is smaller, and the problem of more serious central confluence still exists.

Chinese patent CN201210016443.3 discloses a suction overflow type gas-liquid distributor, which belongs to a tubular distributor in appearance, but combines two characteristics of suction and overflow, the anti-column plate inclination performance is better than that of a tubular type, and the pressure drop is smaller than that of a bubble cap type, but the gas-liquid flow channel of the distributor with the structure is narrow, the operation elasticity is small, and no flow crushing plate exists, and the uniform distribution is difficult to ensure by the venturi diffusion effect alone.

Disclosure of Invention

The invention aims to overcome the defects of relatively serious central confluence and non-uniform liquid distribution of a gas-liquid distributor, and designs the gas-liquid distributor which has good gas-liquid distribution performance and more dispersed liquid.

The invention designs a Venturi type gas-liquid distributor which has the following structure:

the gas-liquid distributor consists of a tubular shell with two closed ends, a reducer pipe arranged in the tubular shell and a venturi pipe arranged at the bottom of the tubular shell, wherein the part below the throat part of the venturi pipe forms an inclined angle of 75 degrees with a base, and 4 waist holes on the side wall have the same size and are uniformly distributed on the tubular shell. The gas phase inlet is an oblique upward notch positioned on the side face of the top of the tubular shell, gas and liquid can be prevented from directly entering the tubular shell from the upper side, compared with a bidirectional opening, the gas can be prevented from directly coming out from the other end after entering the tubular shell, the gas firstly passes through the reducer arranged in the tubular shell after entering the tubular shell, the dynamic pressure reaches the maximum value due to the narrowest pipeline at the outlet of the reducer, the static pressure reaches the minimum value, and the speed of the gas is increased due to the reduction of the cross section area of the channel. The liquid phase inlet is 4 waist holes vertically arranged in the length direction of the tubular shell, and the speed of the liquid phase is increased due to the reduction of the cross section area of the channel. Therefore, the whole main flow fluid undergoes the pipeline shrinking process in the same time, the pressure is also reduced in the same time, a vacuum negative pressure area is formed, a pressure difference is generated, and an external suction force can be provided for the liquid in the pipeline shell through the pressure difference, so that the fluid outside the pipeline shell is sucked into the Venturi tube to be mixed with the gas-phase fluid. After the gas phase and the liquid phase further flow downwards and enter the Venturi tube, the gas phase and the liquid phase are fully mixed due to the fact that the cross section area is suddenly reduced again, and then the gas phase and the liquid phase are sprayed out from the outlet of the Venturi tube, and therefore the purpose of uniform distribution is achieved.

The gas-liquid distributor designed by the invention can improve the liquid crushing performance, so that gas-liquid two phases are more uniformly dispersed to the catalyst bed layer, and the defects of central convergence and non-uniform liquid distribution of the gas-liquid distributor can be effectively overcome.

Drawings

FIG. 1 is a schematic front view of a gas-liquid distributor designed according to the present invention.

Wherein, the device comprises a tubular shell 1, a reducer 2, a liquid phase inlet 3, a Venturi tube 4, a base 5 and a gas phase inlet 6.

FIG. 2 is a comparison graph of the radial distribution of liquid phase fractions under the same conditions for the gas-liquid distributor designed according to the present invention and the flooded gas-liquid distributor. Wherein the ordinate is the liquid phase fraction below the gas-liquid distribution disc at a distance of 200mm from the outlet, and the abscissa is the radial position; the square dotted line is the distribution result of the overflow type gas-liquid distributor, and the circular dotted line is the distribution result of the Venturi type gas-liquid distributor.

Detailed Description

Referring to fig. 1, the gas-liquid distributor designed by the invention has the following detailed structure:

the Venturi type gas-liquid distributor designed by the invention consists of a tubular shell with two closed ends, a reducer pipe arranged in the tubular shell and a Venturi pipe arranged at the bottom of the tubular shell, wherein the tubular shell is vertically arranged, a lower end plate is attached to the upper surface of a distributor tray, and the lower end plate of the tubular shell extends outwards to form a base for stabilizing the tubular shell; a gas phase inlet is formed in the side face of the top of the tubular shell and is higher than the opening edge of the upper end of the reducer pipe; the side surface of the tubular shell is provided with liquid phase inlets at intervals along the circumferential direction, and the liquid phase inlets are higher than the lower end opening of the reducer pipe and lower than the upper end opening of the venturi tube; the reducer pipe is vertically arranged in the tubular shell, the diameter of the reducer pipe is gradually reduced from top to bottom, and the opening edge of the upper end of the reducer pipe is tightly attached to the inner surface of the tubular shell and fixedly connected with the inner surface of the tubular shell; the Venturi tube is vertically arranged in the tubular shell and below the reducer, the opening edge of the upper end of the Venturi tube is tightly attached to the inner surface of the tubular shell and fixedly connected with the inner surface of the tubular shell, the throat part of the Venturi tube penetrates through the lower end plate of the tubular shell and the distributor tray, the part below the throat part of the Venturi tube and the base form an inclined angle of 75 degrees, and 4 waist holes on the side wall of the Venturi tube are identical in size and are uniformly distributed on the tubular shell.

Referring to fig. 1, the preferred scheme of the present invention is that the included angle between the part below the throat of the venturi tube and the base is 15-75 °, the shape of the opening on the upper side wall of the tubular housing is preferably cylindrical, the number of the openings is generally 2-6, and the size and the number of the openings are combined according to the feeding amount of the reactor and the liquid phase ratio in oil gas to achieve the best gas-liquid mixing effect.

The gas-liquid distributor further comprises a flow crushing plate, the flow crushing plate is arranged below the tubular shell 1 and is an open-pore circular flat plate, or a conical connecting plate with an open pore and a circular flat plate with an open pore are combined. The tubular shell 1 is fixedly connected with the base 5 by welding.

It should be noted that, among the main components described in the above embodiments, the optional baffle plate may be included in the design of the present invention.

The working principle of the present invention is described below by taking the gas-liquid distributor shown in fig. 1 as an example.

The gas phase inlet of the Venturi gas-liquid distributor designed by the invention is an obliquely upward notch positioned on the side surface of the top of the tubular shell, and the liquid phase inlet is 4 waist holes vertically arranged in the length direction on the tubular shell. The gas-liquid two-phase flow flows to the upper end of the tubular shell, and the gas and the liquid are prevented from directly entering from the upper part of the tubular shell due to the cover plate arranged at the top of the tubular shell, and the side surface of the top of the tubular shell is obliquely provided with the hole, so that compared with a bidirectional hole, the gas can be prevented from directly coming out from the other end after entering the tubular shell; after entering the tubular housing, the gas firstly passes through a reducer pipe arranged in the tubular housing, and the speed of the gas is increased due to the reduction of the cross-sectional area of the passage; the liquid phase enters from 4 waist holes vertically arranged in the length direction on the tubular shell, and the speed of the liquid phase is increased due to the reduction of the cross section area of the channel; the whole main flow fluid undergoes the pipeline shrinking process in the same time and can provide an external suction force for the liquid of the fluid outside the pipeline shell through pressure difference, so that the fluid outside the pipeline shell is sucked into the Venturi tube to be mixed with the gas-phase fluid. When the gas phase and the liquid phase further flow downwards and enter the Venturi tube, the gas phase and the liquid phase are fully mixed due to the sudden reduction of the section area and then are sprayed out from the outlet of the Venturi tube, so that the aim of uniform distribution is fulfilled.

Further, due to the fact that the Venturi effect of gas-liquid mixing and the diffusion and uniform distribution effect of the flow crushing plates are fully utilized, gas-liquid phase mixing and distribution are improved by improving the structure and layout of a gas-liquid flow channel of the gas-liquid distributor, the gas-liquid mixing degree is obviously enhanced, and meanwhile the dirt containing capacity, the operation elasticity and the application range of the distributor are improved.

Further, due to the fact that gas and liquid phases are fully mixed, the generation of dead zones, channeling and short circuit of the reactor is well reduced, and the problem that part of the catalyst cannot be completely wetted or is excessively used due to the fact that channeling is formed due to uneven distribution is solved.

Further, since the distributors retain the advantages of simple structure and wide operation range, and the two phases of gas and liquid are divided into separate passages, even if the tray is inclined, the gas and liquid flow-through area and flow-through velocity of each distributor on the distribution tray are kept the same, and thus the sensitivity to the inclination of the tray is low.

Furthermore, the distributor has smaller size, so that the distributor tray can be more densely arranged, the number of spraying points is correspondingly increased, and the distribution uniformity can be further improved.

Referring to fig. 2, compared with the prior art, the gas-liquid distributor designed by the invention has the following characteristics: the gas-liquid two-phase flow is distributed more uniformly, the distribution curve is more gentle than that of the prior art, the peak value is 3/4 of that of the prior art, the liquid distribution unevenness is 2/3 of that of the prior art, and the problems of central convergence and uneven liquid distribution of the conventional gas-liquid distributor can be effectively solved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A venturi type gas-liquid distributor, even subsection is on the distributor tray, its characterized in that: comprises a tubular shell with two closed ends, a reducer pipe arranged in the tubular shell and a Venturi pipe arranged at the bottom of the tubular shell;

the tubular shell is vertically arranged, and the lower end plate is arranged close to the upper surface of the distributor tray;

the venturi tube is vertically arranged, the edge of an opening at the upper end is tightly attached to the inner surface of the tubular shell and fixedly connected with the inner surface of the tubular shell, and the throat part penetrates through the lower end plate of the tubular shell and the distributor tray;

the diameter of the reducer pipe is gradually reduced from top to bottom, and the opening edge at the upper end is tightly attached to the inner surface of the tubular shell and fixedly connected with the inner surface of the tubular shell;

the side surface of the top of the tubular shell is provided with a gas phase inlet, the gas phase inlet is an oblique upward notch and is higher than the opening edge of the upper end of the reducer pipe;

the side surface of the tubular shell is provided with liquid phase inlets at intervals along the circumferential direction, and the liquid phase inlets are cylindrical and are arranged below the lower end opening of the reducer pipe and above the upper end opening of the venturi pipe;

in the gas-liquid distributor, the main flow fluid undergoes a pipeline shrinking process at the same time, external suction is provided for the liquid of the fluid outside the pipeline shell through pressure difference, and the fluid outside the pipeline shell is sucked into the Venturi tube to be mixed with the gas-phase fluid;

the liquid phase enters from the liquid phase inlet (3) of the tubular housing, the velocity of the liquid phase increasing as the cross-sectional area of the channel decreases;

and the liquid phase inlet (3) faces the lower end of the reducer pipe, and a gap exists between the liquid phase inlet (3) and the lower end of the reducer pipe (2).

2. The venturi-type gas-liquid distributor according to claim 1, wherein: the liquid phase inlet is a waist hole vertically arranged in the length direction, and 4 liquid phase inlets are formed in the tubular shell.

3. The venturi-type gas-liquid distributor according to claim 1, wherein: the lower end plate of the tubular housing extends outwardly forming a seat for stabilizing the tubular housing.

4. The venturi-type gas-liquid distributor according to claim 1, wherein the diameter of the opening at the lower end of the venturi tube is 2 to 3 times the throat diameter of the venturi tube.

5. A venturi-type gas-liquid distributor as claimed in claim 3 wherein the portion of said venturi below the throat is inclined at an angle of 75 ° to said base.

6. A venturi-type gas-liquid distributor according to claim 1 wherein said distributor is distributed in a regular triangle on the distributor tray.

7. Use of a venturi-type gas-liquid distributor according to any one of claims 1 to 6 in the field of petrochemical industry.

8. Use of a venturi-type gas-liquid distributor according to any one of claims 1-6 in the field of oil refining.

9. A hydrogenation reactor containing a venturi-type gas-liquid distributor as claimed in any one of claims 1 to 6.

10. An apparatus comprising a venturi-type gas-liquid distributor as claimed in any one of claims 1 to 6.