A distributor, distribution assembly and hydrogenation reactor for heavy oil

Abstract

The application discloses a distributor for heavy oil, a distribution assembly and a hydrogenation reactor, relates to the field of heavy oil distribution equipment in a hydrogenation reaction process, and discloses the hydrogenation reactor which is provided with the distribution assembly, the distribution assembly is provided with the distributor, the distributor comprises a central pipe, a baffle plate arranged at the upper end of the central pipe and a flow breaker plate arranged at the lower end of the central pipe, a gas phase inlet is arranged between the baffle plate and the central pipe, overflow holes are formed in the side wall of the central pipe below the gas phase inlet, the overflow holes can be used for allowing the heavy oil to enter the central pipe, a fluid channel with a side opening is formed between the flow breaker plate and the lower end of the central pipe, a plurality of diffusion slots are arranged on the side wall of the lower end of the central pipe in a circumferential direction, the length direction of the diffusion slots is consistent with the length direction of the central pipe, and the diffusion slots extend to the fluid channel in the lower direction. The application is used for solving the problems of excessive pressure drop of the distribution disc and uneven initial gas-liquid distribution of the bed layer caused by poor dispersibility of the oil product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heavy oil distribution equipment in hydrogenation reaction process, and particularly relates to a distributor for heavy oil, a distribution assembly and a hydrogenation reactor. BACKGROUND

[0002] Under the background of increasingly stringent environmental regulations, the standards for impurity content in various petroleum products are also increasing. Sulfur hydrogen technology, as an essential technology in the production process of clean fuel, plays a major role in refinery production. Hydrogenation technology includes hydrocracking, hydrofining, etc. Hydrogenation reaction is an exothermic reaction. At present, most of the domestic down-flow fixed bed reactors are used. The reaction material flows through the catalyst bed from top to bottom and undergoes hydrogenation reaction under the action of the catalyst bed. The uneven distribution of gas and liquid in the bed during the reaction process can lead to hot spots in the reactor, catalyst coking, temperature runaway and other hazards that affect product quality and unsafe production. Therefore, stable gas and liquid distribution is crucial to improve the flow characteristics and catalyst utilization rate in the hydrogenation reactor. The gas and liquid distribution equipment is an internal component that has a significant impact on the initial distribution of gas and liquid in the hydrogenation reactor.

[0003] The distributor and the distribution assembly are both gas-liquid distribution equipment. The commonly used distributor is a tubular gas-liquid distributor. The distribution assembly includes a tubular gas-liquid distributor and a distribution disc provided with distribution holes. The tubular gas-liquid distributor passes through the distribution holes and is fixed on the distribution disc.

[0004] For example, a suction overflow type gas-liquid distributor is disclosed in Chinese Utility Model Patent No. 201520782766.X. The distributor mainly uses the principle of combination of gas-liquid diversion, suction and overflow. Through reasonable structure layout and combination of broken flow plates, uniform distribution of gas and liquid is achieved. However, when using this distributor for hydrogenation reaction of heavy oil, the resistance at the lower end of the distributor is large, the pressure drop is large, and the diffusion effect at the outlet of the current distributor needs to be further improved due to the relatively large viscosity and density of the raw material and the presence of many impurities.

[0005] In addition, the current opening rate of the distribution holes on the distribution disc is generally set by experience, and there is a lack of basis for setting the opening rate. Therefore, the current opening method and the distributor cannot cope with the large range of fluctuations in the amount of gas and liquid, which can easily cause excessive pressure drop of the distribution disc, excessive energy loss, uneven initial gas-liquid distribution in the bed, hot spots in the reactor, catalyst coking, temperature runaway and other hazards that affect product quality and unsafe production. SUMMARY

[0006] The present application aims to provide a distributor for heavy oil, a distribution assembly and a hydrogenation reactor to solve the problems of excessive pressure drop of the distribution disc and uneven initial gas-liquid distribution in the bed caused by poor oil dispersibility.

[0007] In order to solve the above technical problems, the specific scheme adopted by the present application is as follows: a distributor for heavy oil, comprising a central pipe, a baffle plate arranged at the upper end of the central pipe, and a flow breaker plate arranged at the lower end of the central pipe, the baffle plate and the central pipe being provided with a gas phase inlet, the overflow hole being arranged on the side wall of the central pipe below the gas phase inlet, the overflow hole being capable of allowing the heavy oil to enter the central pipe, the flow breaker plate and the lower end of the central pipe forming a side-opened fluid channel, and a plurality of diffusion slots being arranged on the side wall of the lower end of the central pipe in a circumferential direction, the length direction of the diffusion slots being consistent with the length direction of the central pipe, and the diffusion slots extending to the fluid channel below.

[0008] As a further optimization of the above technical solution, the diffusion slots are long strip-shaped slots, the length of the diffusion slots being 20 mm, the width being 2 mm, and the included angle between adjacent diffusion slots being 30°.

[0009] As a further optimization of the above technical solution, the lower end of the diffusion slot and the lower end surface of the central pipe are spaced apart by a distance of 0-10 mm.

[0010] As a further optimization of the above technical solution, the lower end of the diffusion slot is in communication with the fluid channel.

[0011] As a further optimization of the above technical solution, the overflow holes are arranged in multiple layers and staggered in the circumferential direction of the central pipe.

[0012] As a further optimization of the above technical solution, the lower end of the central pipe is connected to the flow breaker plate through a plurality of spaced-apart connecting legs, and the connecting legs are staggered with the diffusion slots.

[0013] As a further optimization of the above technical solution, the pipe diameter of the central pipe is 35-42 mm.

[0014] A distribution assembly for heavy oil, comprising a distribution disc, a plurality of distribution holes being arranged on the distribution disc, each distribution hole being provided with the above-mentioned distributor, the central pipe of the distributor penetrating through the distribution hole and being fixed vertically on the distribution disc, the overflow hole being arranged above the distribution disc, the diffusion slot being arranged below the distribution disc, and the opening rate of the distribution holes on the distribution disc satisfying the following formula:

[0015] x≤(ρ g Q g d0 2 ) / (RSσμ 2 )

[0016] wherein ρ g is the gas phase density, u g is the gas phase velocity, d0 is the initial droplet diameter, σ is the liquid phase surface tension, Q g is the gas phase flux, S is the cross-sectional area of the distribution disc, x is the opening rate of the distribution disc, and R is a constant between 2.0 and 2.5.

[0017] As the further optimization of the above technical solution, the opening rate of the distribution holes on the distribution plate is 10-30%.

[0018] As the further optimization of the above technical solution, the distance between any distribution hole on the distribution plate and the closest distribution hole around it is equal.

[0019] As the further optimization of the above technical solution, the distance between any two adjacent distribution holes is 80-150 mm.

[0020] As the further optimization of the above technical solution, the distance between the lowermost overflow hole and the upper surface of the distribution plate is 50-100 mm.

[0021] As the further optimization of the above technical solution, the distance between the upper end of the diffusion slit and the lower surface of the distribution plate is 2-10 mm.

[0022] A hydrogenation reactor for heavy oil, which has the above distribution assembly.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] 1. The present application proposes a distributor structure and a suitable arrangement and opening rate. The properties of oil (viscosity, surface tension) are associated with the distributor structure and the opening rate of the distribution plate, and a correlation formula based on the aerodynamic energy is proposed. The opening rate of the distribution plate is limited by the liquid viscosity and surface tension as the design basis for the hydrogenation distributor, and the opening rate selection basis for the gas-liquid distribution plate in the heavy oil hydrogenation reactor is proposed.

[0025] 2. Considering that the distributor is applied in the environment of heavy oil, the gas-liquid distributor is arranged in a regular triangle on the distribution plate, which ensures that the liquid phase on the distribution plate can smoothly enter the central pipe of the distributor.

[0026] 3. Because the lower end of the central pipe has large resistance and pressure drop, and the flowability of heavy oil is poor, the diffusion slit arranged on the distributor can accelerate the diffusion of heavy oil at the outlet of the central pipe. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structure schematic view of the distributor in Example 1.

[0028] Figure 2 It is a side sectional view of the distributor in Example 1.

[0029] Figure 3 It is a sectional view of the A-A direction. Figure 2

[0030] Figure 4 It is a sectional view of the B-B direction. Figure 2 ​Schematic diagram of the cross section in the middle BB direction;

[0031] Figure 5 for Figure 2 A schematic diagram of the cross-section in the CC direction;

[0032] Figure 6 This is a schematic diagram of the distributor in Example 2;

[0033] Figure 7 This is a schematic diagram of the distribution disk structure with distribution holes in Embodiment 3;

[0034] Reference numerals: 1. Baffle, 2. Gas inlet, 3. Central tube, 4. Overflow hole, 5. Diffusion slot, 6. Fluid channel, 7. Connecting leg, 8. Flow breaker, 9. Distribution plate, 10. Distribution hole, 11. Connecting rod. Detailed Implementation

[0035] Example 1

[0036] like Figure 1 , Figure 2 As shown, this embodiment is a distributor for heavy oil. When in use, the distributor is first fixedly installed on the distribution plate 9, and then installed in the hydrogenation reactor along with the distribution plate 9.

[0037] The distributor includes a central tube 3, a baffle 1 disposed at the upper end of the central tube 3, and a flow-breaking plate 8 disposed at the lower end of the central tube 3. The central tube 3 is a straight circular tube with a diameter of 35-42 mm and a wall thickness of 2-6 mm, such as 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, or 6 mm.

[0038] The baffle 1 is used to prevent the gas and liquid at the top of the hydrogenation reactor from directly entering the central tube 3. The baffle 1 is circular and coaxially distributed with the central tube 3. The diameter of the baffle 1 is equal to or slightly larger than the inner diameter of the central tube 3. It is used to block the gas and liquid flow from top to bottom, preventing the gas-liquid mixture from directly entering the central tube 3 and causing short circuits or uneven gas-liquid distribution.

[0039] A gas phase inlet 2 is located between the baffle 1 and the central tube 3, at the uppermost end of the central tube 3. For example... Figure 3 , Figure 4 As shown, the upper end of the central tube 3 is connected to the lower surface of the baffle 1 via two vertical connecting rods 11, forming the gas inlet 2 between the two vertical connecting rods 11. Alternatively, the baffle 1 and the upper end of the central tube 3 can be fixedly connected, with the gas inlet 2 located on the side wall of the central tube 3 and below the baffle 1. There are two gas inlets 2 arranged opposite each other, and the shape of the gas inlets 2 is rectangular.

[0040] As Figure 2 , Figure 4 shown, the center tube 3 side wall below the gas phase inlet 2 is provided with overflow holes 4, the overflow holes 4 are multi-layered and staggered in the circumferential direction of the center tube 3. The role of the overflow hole 4 is mainly to pass heavy oil liquid into the center tube 3, the multi-layered staggered arrangement of the overflow hole 4 can ensure that when the load is large, it can still maintain a stable working state. In actual setting, the diameter and direction angle of the overflow hole 4 can also be changed as needed. It should be noted that the overflow hole 4 can also be used as a gas phase inlet for gas phase to pass in when the liquid phase load is small.

[0041] The overflow hole 4 in the embodiment is provided as 6, every two overflow holes 4 are oppositely arranged on the center tube 3, and every two overflow holes 4 are a layer. The height of each layer of overflow holes 4 is consistent, so the overflow holes 4 in the embodiment are provided as three layers. The diameter of each overflow hole 4 can be set to 8-15mm. In the embodiment, according to the distance from the distribution disc 9, the overflow hole 4 close to the distribution disc 9 is the first layer of overflow hole, and the second layer of overflow hole and the third layer of overflow hole are sequentially upward. The angle of the first layer of overflow hole and the second layer of overflow hole in the horizontal direction is consistent, and the second layer of overflow hole and the third layer of overflow hole are staggered by 90 degrees in the horizontal direction.

[0042] The gas mainly enters the center tube 3 through the gas phase inlet 2. The high-speed gas flowing in the tube forms a pressure difference between the inside and outside of the tube, and then the liquid oil outside the tube is sucked into the center tube 3 through the overflow hole 4.

[0043] The broken flow plate 8 is fixed to the lower end of the center tube 3 through a plurality of connecting legs 7. The number of connecting legs 7 is uniformly arranged as 4, which can as far as possible not block the fluid under the premise of ensuring the strength, and the fluid passage 6 is formed between the connecting legs 7. The diameter of the broken flow plate 8 is slightly larger than the diameter of the center tube 3.

[0044] As Figure 1 , Figure 2 and Figure 5 shown, a plurality of diffusion slots 5 are uniformly and spaced apart in the circumferential direction on the side wall below the center tube 3. The length direction of the diffusion slot 5 is consistent with the length direction of the center tube 3, and extends to the fluid passage 6 below. The diffusion slot 5 is a long strip-shaped slot, the diffusion slot 5 is located below the overflow hole 4, and the height of all diffusion slots 5 is consistent. The size of each diffusion slot 5 is the same. The length of the diffusion slot 5 is 20mm, and the width is 2mm. As Figure 5 shown, the diffusion slots 5 provided on the center tube 3 are 12, and the included angle between adjacent diffusion slots 5 is 30°.

[0045] The lower end of the diffusion slot 5 is connected to the fluid channel 6. Due to the large resistance, large pressure drop, and poor fluidity of the heavy oil at the lower end of the central pipe 3, the ability to diffuse rapidly is insufficient. The diffusion slot 5 set below the central pipe 3 can alleviate the resistance and pressure drop at the lower end of the central pipe, improve the rapid diffusion of the heavy oil, and the gas-liquid mixture can also overflow from the diffusion slot 5 to achieve zoned diffusion.

[0046] Example 2

[0047] like Figure 6 As shown, the main structure of this embodiment is the same as that of embodiment 1. The difference is that there is a gap of 0 to 10 mm between the lower end of the diffuser slit 5 and the lower end face of the central tube 3. The gap between the lower end of the diffuser slit 5 and the lower end face of the central tube 3 is sufficient to allow the mixed airflow in the central tube 3 to overflow from the diffuser slit 5. Furthermore, when the gap is greater than 0 mm, the setting of the gap can also ensure the stability and firmness of the central tube 3 structure.

[0048] Example 3

[0049] like Figure 1 , Figure 2 and Figure 7 As shown, this embodiment is a distribution assembly for heavy oil, installed inside a heavy oil hydrotreating reactor. The distribution assembly includes a distribution disk 9 and the aforementioned distributor. The distribution disk 9 has multiple distribution holes 10. The distributor passes vertically through the distribution holes 10 and is fixed to the distribution disk 9. The portion of the distributor located above the distribution disk 9 is larger than the portion located below it. The baffle 1 and the flow breaker 8 are both parallel to the distribution disk 9. An overflow hole 4 is located above the distribution disk 9, with the lowest overflow hole 4 50–100 mm from the upper surface of the distribution disk 9. A diffusion slit 5 is located below the distribution disk 9, with its upper end 2–10 mm from the lower surface of the distribution disk 9.

[0050] This invention proposes a suitable arrangement and porosity to match the distributor, and correlates the properties of the oil (viscosity, surface tension) with the porosity of the distribution plate 9, providing a basis for selecting the porosity of the distribution plate 9 in a hydrogenation reactor for heavy oil.

[0051] The relationship between aerodynamic forces and surface tension is generally characterized by the Weber number, a dimensionless number that is positively correlated with gas phase density, gas phase velocity, and droplet diameter, and inversely correlated with surface tension.

[0052] Laboratory experiments and data fitting were conducted to ensure the uniformity of gas-liquid phase distribution. The Weber number needs to be greater than the dimensionless number R. The porosity of the distribution holes 10 on the distribution disk 9 satisfies the following formula:

[0053] x≤(ρ g Q g d0 2) / (RSσμ 2 )

[0054] Where ρ g U is the gas phase density; g d0 is the gas phase velocity within the distributor; σ is the initial droplet diameter; Q is the liquid phase surface tension; g denoted as ρ, where ρ is the gas flow rate of the reactor; S is the cross-sectional area of ​​the distribution disk 9; x is the porosity of the distribution disk 9; and R is a constant between 2.0 and 2.5.

[0055] The diameter of the central tube 3 is 35-42 mm, which means the diameter of the distribution hole 10 is also 35-42 mm, and the opening ratio of the distribution plate 9 is 10-30%. Within this opening ratio range, the heavy oil can be fully absorbed, while avoiding oil blockage of the distributor.

[0056] Any distribution hole 10 on the distribution disk 9 is equidistant from the nearest surrounding distribution hole 10, such as... Figure 6 As shown, the distribution disk 9 has multiple rows of distribution holes 10, with adjacent rows of distribution holes 10 staggered. The arrangement of four adjacent distribution holes 10 within two adjacent rows forms a rhombus with an acute angle of 60°, meaning the distribution holes 10 are distributed in an equilateral triangle on the distribution disk 9. The distance between two adjacent distribution holes 10 within the same equilateral triangle is 80–150 mm, referring to the distance between the centers of two adjacent distribution holes 10. Therefore, the distributors on the distribution disk 9 are also arranged in an equilateral triangle layout, with a spacing of 80–150 mm. This equilateral triangle layout ensures that the liquid phase on the distribution disk 9 smoothly enters the central tube 3 of the distributor.

[0057] The working principle of the present application is that the gas-liquid phase mixture of heavy oil and hydrogen flows from the upper part of the reactor, and the liquid phase first contacts the baffle 1 at the upper part of the distributor, and does not directly enter the inside of the central pipe 3. The baffle 1 buffers and deflects the gas-liquid phase mixture flow to the distribution disc 9. Considering that the oil in the gas-liquid phase mixture flow is heavy oil, which has the characteristics of many impurities, large density, poor flowability, and large viscosity, the distributor is arranged in a regular triangle shape to ensure that the liquid phase above the distribution disc 9 can be smoothly and uniformly distributed into each central pipe 3 of the distributor. The gas phase mainly enters the central pipe 3 from the gas phase inlet 2 at the upper part of the central pipe 3, and a part of the gas also enters the inside of the central pipe 3 from the overflow hole 4 at the upper layer. The high-speed gas flowing in the pipe forms a pressure difference between the inside and the outside of the pipe, and the liquid on the distribution disc 9 is sucked into the overflow hole 4 and then flows into the central pipe 3, and is mixed with the gas phase in the central pipe 3 to form a gas-liquid mixed fluid. The gas-liquid mixed fluid flows downward in the central pipe 3, and finally collides with the broken flow plate 8 below the central pipe 3. The broken flow plate 8 makes the gas-liquid mixed fluid change from downward flow to radial planar flow by impact, and part of the gas-liquid mixed fluid is splashed and diffused around. The larger broken flow plate 8 is more conducive to the diffusion of the gas-liquid two phases. The gas-liquid mixtures flowing out of the multiple central pipes 3 collide with each other and are uniformly distributed to the catalyst bed layer. At the same time, due to the large resistance and large pressure drop at the lower end of the central pipe 3, and the poor flowability and weak rapid diffusion capacity of the heavy oil, the diffusion slit 5 arranged on the central pipe 3 can accelerate the diffusion of the heavy oil at the outlet.

[0058] The design of the opening rate of the distribution disc 9 can optimize the installation position of the distributor on the distribution disc 9, so that the gas-liquid mixed fluid after impacting the broken flow plate 8 does not splash onto the broken flow plate 8 of the adjacent distributor, but collides with the gas-liquid mixed fluid splashed from the adjacent broken flow plate 8 again, thereby improving the distribution efficiency.

[0059] Example 4

[0060] The present embodiment discloses a hydrogenation reactor for heavy oil, which has the above-mentioned distribution assembly, can uniformly distribute the initial gas-liquid to the catalyst bed layer, avoid the generation of hot spots in the hydrogenation reactor, catalyst coking, temperature runaway and other hazards that affect product quality and unsafe production.

Claims

1. A distributor for heavy oil, comprising a central tube (3), a baffle (1) disposed at the upper end of the central tube (3), and a flow-breaking plate (8) disposed at the lower end of the central tube (3), wherein a gas inlet (2) is provided between the baffle (1) and the central tube (3), and an overflow hole (4) is provided on the side wall of the central tube (3) below the gas inlet (2), the overflow hole (4) allowing heavy oil to enter the central tube (3), and a fluid channel (6) with a side opening is formed between the flow-breaking plate (8) and the lower end of the central tube (3), characterized in that, Multiple diffusion slits (5) are opened circumferentially on the side wall at the lower end of the central tube (3). The length direction of the diffusion slits (5) is consistent with the length direction of the central tube (3) and extends to the fluid channel (6) below. The diffusion seam (5) is a long strip seam with a length of 20 mm and a width of 2 mm. The included angle between adjacent diffusion seams (5) is 30°. The lower end of the diffusion slit (5) is connected to the fluid channel (6).

2. A distributor for heavy oil according to claim 1, characterized in that, A gap of 0~10mm is left between the lower end of the diffusion joint (5) and the lower end face of the central tube (3), and the gap is not 0.

3. A distributor for heavy oil according to claim 1, characterized in that, The overflow holes (4) are multi-layered and are staggered in the circumferential direction of the central tube (3).

4. A distributor for heavy oil according to claim 1, characterized in that, The lower end of the central tube (3) is connected to the flow plate (8) through multiple spaced connecting legs (7), and the connecting legs (7) are staggered from the position of the diffuser slit (5).

5. A distributor for heavy oil according to claim 1, characterized in that, The diameter of the central tube (3) is 35~42mm.

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