Centrifugal oil washing device and method for oil-containing spent catalyst

Abstract

The present application relates to a kind of technical upgrading of waste catalyst treatment process in petroleum refining process, and a new type of centrifugal washing equipment is provided by independent research and development, the equipment is composed of rack, shell, drum assembly, spray system, transmission system etc., while the complete set of oil removal device including hopper feeder, washing oil tank, washing oil pump, screw conveyor, preheater and gas-liquid separation tank etc. is built with the equipment. A centrifugal washing and oil removal method for oil-containing waste catalyst is also provided, which includes the following steps: (a) collecting and automatically feeding waste catalyst slurry; (b) primary centrifugal washing, using light oil as an extractant to remove heavy oil impurities on the surface of the catalyst; (c) recycling waste oil, and periodically recovering waste oil; (d) secondary centrifugal washing, using hot gas at a certain temperature to blow and strip oil droplets on the surface of the catalyst, and recovering the catalyst after deep purification; (e) gas-liquid separation of oil-containing waste gas to obtain clean cooling gas and waste oil.

Description

Technical Field

[0001] This invention belongs to the field of waste catalyst treatment technology, specifically relating to a method and apparatus for centrifugally washing and removing oily substances from waste catalysts recovered during petroleum refining. Background Technology

[0002] Catalysts play a crucial role in national economic development, improving product yield and reducing process energy consumption. For example, in petroleum refining, hydrodesulfurization typically uses catalysts with porous aluminum substrates and supported on valuable metals such as molybdenum-nickel or tungsten-nickel as activation centers. After a certain period of use, fouling or oil deposits accumulate in the catalyst's pores, leading to poisoning and loss of activity. Therefore, a large amount of deactivated spent catalyst is generated in refining units periodically, requiring replacement. To maintain long-term operation of the unit, this spent catalyst is usually discharged online along with the hydroreaction process. Due to the high specific surface area and strong adsorption capacity of the catalyst, the spent catalyst slurry carries a large amount of residual oil and is discharged from the reactor discharge port, resulting in a very high oil content in the mixture, typically 15-30% oil. These oily substances have high viscosity, density, and oxygen content, and their complex composition and wide distillation range make them difficult to remove efficiently and costly using conventional methods, thus hindering effective separation. In addition, the waste catalyst contains a large amount of toxic and harmful metals deposited during the hydrogenation reaction, such as vanadium, molybdenum (tungsten), nickel, and cobalt. Direct landfilling would not only result in a huge waste of resources but also severely pollute the environment.

[0003] Currently, there are two main methods for treating such spent catalysts: one is direct roasting for desulfurization and decarbonization pretreatment followed by further extraction of the loaded metal; the other is deoiling the spent catalyst before further roasting for desulfurization and extraction of the loaded metal. The former has been used in some production facilities, but the cost of treating the solid waste generated by roasting accounts for almost half of the total production cost; in contrast, the latter has attracted more attention from researchers. Scholars have studied the processes and methods for deoiling spent catalysts, such as using NaOH leaching or using the anionic surfactant sodium dodecyl sulfate (SDS) as an emulsifier for leaching, and also using alcohol for leaching under ultrasonic vibration and mechanical stirring, but none of these have been put into production due to technical or cost reasons. At present, there are few reports on effective methods for catalyst deoiling both domestically and internationally, and the existing deoiling methods in industrial facilities are relatively complex, energy-intensive, and ineffective.

[0004] Chinese invention patent CN104673356B discloses a method for treating oily waste catalyst discharged from a fluidized bed reactor. The method employs a two-stage series extraction reactor to treat the oily waste catalyst discharged from the fluidized bed. First, utilizing the enhanced solubility of solvent oil after reaching a supercritical state, upstream discharged light hydrocarbons are used as the primary extractant in the first-stage extraction reactor to conduct a supercritical extraction reaction with the oily waste catalyst. The resulting raffinate enters the second-stage extraction reactor, where one or more of the light oil obtained from the fluidized bed fractionation system and the light oil separated from the first-stage extractant are used as the secondary extractant for deep extraction of the waste catalyst. This method requires no additional heat exchange or pressurization equipment. The two-stage, double-row extraction reactors connected in series can achieve self-equilibrium of the extracted materials, essentially achieving the harmless treatment of the catalyst while ensuring the effective utilization of oil and gas. Invention patent CN102698816B provides another method and apparatus for treating waste catalyst discharged from fluidized bed residue oil: the waste catalyst is first treated using a traditional hydrothermal desorption method, then heterogeneous cyclone separation is used to obtain catalyst slurry and oil-water mixture, and the oil-water mixture is further separated by cyclone separation to obtain aqueous and oil phases. The aqueous phase is returned to the hydrothermal desorption process as circulating water, while the oil phase undergoes gravity sedimentation separation for further dehydration and recovery. The enriched catalyst particles are then returned for drying, ultimately achieving reduced catalyst particle recovery. Invention patent CN110819371B relates to an apparatus and method for continuously refluxing to remove oil from waste aluminum-based catalysts. It provides a novel treatment device including a waste catalyst treatment chamber and a mesh frame for holding the waste catalyst. It utilizes a combination of light oil reflux and steam purging to deeply wash and remove heavy and light oil components from the surface of the waste aluminum-based catalyst, achieving complete separation of oil from valuable elements in the catalyst.

[0005] Currently, China lacks mature technology for treating spent catalysts, particularly for those discharged from heavy oil hydrogenation units. The main problems are as follows: (1) Some deoiling methods involve adding water-soluble polymeric dispersants, alcohols, and other substances, combined with ultrasonic vibration and mechanical stirring. This requires high-quality equipment, complex processes, and subsequent wastewater treatment, failing to address the fundamental issue. (2) Current deoiling technologies rely on online discharge after treatment in reactors or extractors. The deoiling process requires purging and stripping the entire equipment. However, since spent catalysts contain both lighter fractions and unreacted heavy residue, high-temperature and high-volume hot nitrogen gas is required to ensure thorough stripping, increasing the energy consumption of the entire unit. (3) While multi-stage deoiling using heterogeneous cyclone separation technology is efficient, the spent catalyst is easily broken and pulverized during processing, causing blockages in downstream equipment or filtration devices. Furthermore, high feed flow rates are required, leading to wear on the inner walls of the separation equipment and making long-term operation difficult. Therefore, there is an urgent need to develop an environmentally friendly, efficient, low-investment, and simple-to-operate spent catalyst treatment technology. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides an efficient and simple method and apparatus for centrifugal washing and oil removal of oily waste catalysts, which solves some of the problems existing in the existing waste catalyst treatment process.

[0007] The technical concept of this invention is as follows: Waste catalysts mainly include residual oil catalysts and regenerated catalysts. The main components of the surface deposits are residual oil or wax oil. The oil phase density is very close to that of water and has strong adhesion. Therefore, this invention uses a self-developed centrifugal washing device to perform two-stage deep deoiling treatment on oily waste catalysts through oil washing + hot gas washing.

[0008] This invention is achieved through the following technical solution:

[0009] A centrifugal washing and oil removal device for oily waste catalysts, characterized in that the device comprises: a cantilever elevator 101 connected to a first hopper feeder 102, the bottom of the first hopper feeder 102 connected to the top of a first centrifugal scrubber 103, a washing oil tank 107 connected to the side inlet of the first centrifugal scrubber 103 via a washing oil pump 106, the bottom of the first centrifugal scrubber 103 connected to the washing oil tank 107 via a three-way valve 104, and sequentially connected to a first screw conveyor 108, a second hopper feeder 109, and a second centrifugal scrubber 110 via a three-way valve 104, the side inlet of the second centrifugal scrubber 110 receiving purge gas from a utility system via a preheater 111, and the gas phase outlet of the second centrifugal scrubber 110 connected to a waste gas buffer tank 113, the bottom of which is connected to a second screw conveyor 112, and a fiber coalescing internal component 114 disposed on the top of the waste gas buffer tank 113;

[0010] The first centrifugal washer 103 and the second centrifugal washer 110 are horizontal centrifugal washers with identical structures, including a frame 1, a housing 2, a drum assembly 3, a spray system 4, and a transmission system 5.

[0011] The outer shell 2 is mainly composed of a cylindrical body 21 and a bottom hopper 22. The outer shell 2 is placed above the frame 1 and the two are fixed by welding or bolts. The drum assembly 3 is placed inside the outer shell 2 and is arranged coaxially and centrally with the outer shell 2. The axial distance between the inner wall of the outer shell and the outer wall of the drum assembly 3 is 100-500mm.

[0012] The drum assembly 3 mainly includes a drum body 31, an electric opening device 32, and a main shaft 33. The electric opening device 32, which is used to open during feeding or unloading, is powered by an electro-hydraulic or electric guide rail type. The drum body 31 consists of an outer drum wall 34, an axial baffle 35, and drainage holes 36. The outer drum wall 34 is coaxially arranged with the main shaft 33. The axial baffle 35 is evenly arranged on the inner side of the outer drum wall 34, and the drainage holes 36 are evenly distributed on the outer drum wall 34.

[0013] The spray system 4 includes a feed pipe 41, a nozzle 42, and a backwash pipe 43. The nozzles 42 are evenly distributed around the feed pipe 41. The feed pipe 41 is coaxially arranged with the drum assembly 3, passes through the outer shell 2, and extends into the drum assembly 3. The distance between the feed pipe 41 and the inner side of the outer wall 34 of the drum is 50-200mm. The feed pipe 41 is connected and fixed to the external pipeline through a rotary joint 44. It is linked with the drum during operation. The backwash pipe 43, which is used to flush the drainage tear hole 36, is fixed on one side of the inner wall of the outer shell.

[0014] The transmission system 5 is located on one side of the frame 1 and the outer shell 2, and is coaxial with the drum assembly 3. The motor 51 is located outside the cover plate 52, and the coupling 53 is connected to the motor 51 via the bearing 54 and passes through the outer shell 2 to be connected to the drum assembly 3 on the same side.

[0015] In the centrifugal washer described above, there are 6 to 12 axial baffles 35 inside the drum, with a thickness of 5 to 20 mm and a length consistent with the length of the drum body 31; the drainage tear hole 36 has a diameter of 1 to 5 mm and an opening rate of 20% to 40% of the unfolded surface of the outer wall 34 of the drum.

[0016] In the centrifugal scrubber, the number of nozzles 42 on the feed pipe 41 of the spray system is 24 to 60. The nozzles 42 are selected according to the oil content of the waste catalyst, preferably one of spiral atomizing nozzles, built-in twisted blade nozzles, and straight nozzles. The spray pressure of the nozzles 42 is 0.2 to 2 MPa, and the droplet size range is 50 to 500 μm. The bottom side of the cylindrical body 21 of the outer shell is provided with a drain to prevent liquid from accumulating inside the outer shell 2 after shutdown backwashing.

[0017] The device employs DCS remote control to achieve automated operation with human-machine isolation. The amount of oil in the waste catalyst before the second centrifugal scrubber can be adjusted according to the oil content (whether it exceeds 40%) or the viscosity, density, and oxygen content of the oil. The centrifugal scrubber can be set to three or more stages.

[0018] In a preferred embodiment, the electric opening device on the centrifugal washer drum assembly is a skylight-type electric hatch embedded in the outer wall of the drum.

[0019] In another preferred embodiment, the electric opening device on the centrifugal washer drum assembly is an electrically driven semi-open drum body.

[0020] Preferably, the fiber coalescing inner part at the top of the waste gas buffer tank is a double-helix heterogeneous fiber mixed inner part or a combination of oblique corrugated plate and heterogeneous fiber mixed inner part to improve the gas-liquid separation effect.

[0021] The present invention also provides a method for centrifugal washing and degreasing of oil-containing waste catalyst, characterized in that the method includes the following steps:

[0022] (a) Collection and transportation: First, the waste catalyst slurry is collected and brought to the top of the closed conveyor belt by the cantilever elevator 101. Then, it is slowly fed into the first hopper feeder 102 by the closed conveyor belt.

[0023] (b) Oil washing: Automatic feeding is achieved by cooperating with the electric door of the first centrifugal scrubber 103 drum, so that the slurry collected in step (a) enters the drum area of ​​the first centrifugal scrubber 103. After feeding is completed, the door is closed; washing oil is sprayed into the drum. In the first centrifugal scrubber 103, the rotating drum makes the slurry and washing oil fully mixed. The washing oil extracts the oily substances from the catalyst surface and, under the action of centrifugal force, discharges them into the bottom hopper 22 of the first centrifugal scrubber through the drain hole 36 of the drum shell, thus achieving liquid-solid separation.

[0024] (c) Unloading: The washing waste oil generated in step (b) is returned to the washing oil tank 107 for recycling through the three-way valve 104. Whether to discharge and recycle is determined according to the saturation of the washing oil. During operation, the system automatically replenishes fresh oil or stops the pump according to the liquid level change in the washing oil tank 107. After the washing waste oil in the bottom hopper of step (b) is discharged, the position of the drum is adjusted to be directly above the bottom hopper 22, the electric hatch is opened, and the waste catalyst is unloaded.

[0025] (d) Purging: The spent catalyst from the bottom hopper 22 in step (c) is subjected to a two-stage centrifugal washing process. Through the switching of the three-way valve 104 and the conveying of the first screw conveyor 108, the spent catalyst is sent to the drum area of ​​the second centrifugal scrubber 110. In the drum of the second centrifugal scrubber 110, hot air is introduced to purge the spent catalyst particles. The washing oil remaining on the catalyst surface is continuously vaporized by gas lifting, further removing oil stains from the spent catalyst and generating oily exhaust gas. The purified catalyst is unloaded in the manner described in step (c). The catalyst collected in the bottom hopper 22 is then conveyed to the product recovery tank or enters the regeneration unit via the second screw conveyor 112.

[0026] (e) Gas-liquid separation: The oily waste gas generated in step (d) enters the gas stripping waste gas buffer tank 113 through the gas phase outlet of the outer shell of the second centrifugal scrubber 110. As the temperature naturally cools down, the washing oil entrained in the gas phase condenses into droplets and is captured and separated by the fiber coalescing inner part 114 at the top of the buffer tank, obtaining clean cooling gas and waste oil, which are sent to the downstream collection system for recycling.

[0027] In the centrifugal washing and separation method, the washing oil used for oil washing is one of catalytic gasoline, catalytic diesel, hydrogenated gasoline, hydrogenated diesel, kerosene, topping oil, and residual oil, and the oil washing time is 15-30 min; the purging gas used for the secondary gas stripping separation is one of nitrogen and dry air, and the purging time is 20-40 min.

[0028] In step (b), the flow ratio of the waste catalyst to the washing oil entering the first centrifugal scrubber 103 is 2:1 to 4:1, the pressure drop is 0.05 to 0.2 MPa, and the washing oil flow rate is 0.25 to 1.5 m / s.

[0029] The waste catalyst discharged in step (c) is a vacuum residue catalyst with an oil content of 20-30% and an oil phase density of 1.0-1.1 g / cm³. 3 Viscosity of 1000-1200 mm 2 / s, with catalyst particle size ranging from 2 to 8 mm;

[0030] Alternatively, the waste catalyst discharged in step (c) can be a regenerated catalyst with an oil content of 10-20% and an oil phase density of 0.8-0.9 g / cm³. 3 Viscosity is 120-150 mm 2 / s, the catalyst particle size range is 0.5~6mm;

[0031] In step (d), the flow ratio of the waste catalyst to the purge gas entering the second centrifugal scrubber 110 is 1:1 to 1:3, the preheating temperature of the purge gas is 230℃ to 370℃, the inlet pressure is 8.5MPa to 18MPa, the pressure drop is 0.5 to 5MPa, and the purge gas velocity is 30 to 80mm / s.

[0032] Preferably, in the centrifugal washing and separation method, a pipeline filter 105 is installed before the washing waste oil generated in step (c) enters the washing oil tank 107 to prevent small-sized pulverized particles from being carried away when the circulating washing oil returns to the system. The frequency of circulating waste oil discharge is determined according to the filter backwashing frequency. At the same time, after the circulating waste oil is discharged, fresh washing oil is added to the washing oil tank 107. The amount of replenishment must ensure that the flow ratio of waste catalyst to washing oil in the first centrifugal scrubber 103 remains constant at 2:1 to 4:1.

[0033] The main beneficial effects of this invention are:

[0034] (1) The method is simple and easy to implement, and the equipment is highly efficient and energy-saving. This method is applied for the first time to the post-treatment process of waste catalysts, using oil washing + gas stripping to perform two-stage deep deoiling treatment on oily waste catalysts. The total processing time of this equipment does not exceed 1 hour, realizing automated production with human-machine separation. The oil content of the recovered catalyst after washing is less than 2%, and it saves 20-40% of the washing oil consumption;

[0035] (2) This method uses light oil as a detergent, which effectively improves the mass transfer efficiency. After the washing process is completed, there will be no problem of external discharge of wastewater or waste gas. Moreover, it can recover high-value waste oil, protect the environment and reduce the treatment cost.

[0036] (3) Compared with conventional fluidized bed or cyclone separation technologies used in refineries, centrifugal washing technology changes the liquid-solid separation method of the catalyst. This new method not only has the advantages of low pressure drop and good mass transfer, but its low rotation speed also effectively prevents catalyst particle breakage. In addition, hot nitrogen or dry air is used to replace steam during the stripping process, and a two-stage gradient treatment process is adopted to reduce the amount of stripping gas and the preheating temperature. This not only solves the serious calcination and pulverization problem in the regeneration of hydrophilic catalysts, but also significantly reduces the overall energy consumption of the unit. Attached Figure Description

[0037] The objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings. The drawings are provided to offer a further understanding of the invention, and constitute only a part of this specification to further explain the invention, but do not constitute a limitation thereof:

[0038] Figure 1 This is a simplified process flow diagram of the centrifugal washing and separation method of the present invention.

[0039] Among them, 101: cantilever elevator, 102: first hopper feeder, 103: first centrifugal washer, 104: three-way valve, 105: pipeline filter, 106: washing oil pump, 107: washing oil tank, 108: first screw conveyor, 109: second hopper feeder, 110: second centrifugal washer, 111: preheater, 112: second screw conveyor, 113: air-lift waste gas buffer tank, and 114: fiber coalescing internals.

[0040] Figure 2 This is a schematic diagram illustrating the working principle of the centrifugal washer in this invention.

[0041] Figure 3 This is a three-dimensional structural diagram of a centrifugal washer device designed independently according to an embodiment of the present invention.

[0042] Among them, 1: frame, 2: outer shell, 3: drum assembly, 4: spray system, 5: transmission system, 21: cylinder body, 22: bottom hopper, 43: backwash pipe, 51: explosion-proof three-phase asynchronous motor, 52: cover plate, 53: coupling, 54: bearing.

[0043] Figure 4 This is a three-dimensional schematic diagram of the internal structure of a centrifugal washer drum, designed independently according to an embodiment of the present invention.

[0044] Among them, 31: drum body, 32: electric opening device, 33: main shaft, 34: outer wall of drum, 35: axial baffle, 36: drainage tear hole.

[0045] Figure 5(a) is a three-dimensional schematic diagram of the spray internal structure of a centrifugal washer designed according to an embodiment of the present invention, and Figure 5(b) is a left view of the spray internal nozzle arrangement.

[0046] Among them, 41: feed pipe, 42: nozzle, 44: rotary joint. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0048] Through long-term engineering practice and experimental research, the inventors of this application have identified problems with existing methods, such as low automation, difficulty in wastewater treatment, high energy consumption, and easy breakage of catalysts. These methods not only fail to fully meet environmental protection requirements but also cannot achieve the efficient and safe production needs of catalyst post-treatment processes. Based on the concept of "high efficiency, separation, and recovery," this invention proposes a novel centrifugal washing method and apparatus for removing oil from oily waste catalysts. The method and apparatus of this invention are highly efficient and energy-saving. During implementation, no excess wastewater, waste gas, or other pollutants are generated, and the washing oil is recycled as much as possible. This reduces the amount of stripping gas and the preheating temperature, thus fully realizing the resource-based treatment of waste catalysts.

[0049] Figure 1 This is a simplified process flow diagram of the centrifugal washing and separation method of the present invention. (See diagram below.) Figure 1 As shown, the process mainly consists of three stages:

[0050] (1) Oil washing

[0051] After arriving at the unit via freight transport, the spent / regenerated catalyst is first hoisted to the top of a closed conveyor belt by a cantilever elevator, and then slowly fed into a hopper feeder by the closed conveyor belt. Automatic feeding is achieved through the hopper feeder's coordination with the electrically operated drum opening device of the first centrifugal scrubber. The oil-containing catalyst enters the drum area of ​​the first centrifugal scrubber, and the hatch is closed after feeding. Washing oil is then sprayed into the first centrifugal scrubber. In the rotating drum, the two phases are thoroughly mixed, and the washing oil dissolves the residual oil or wax oil on the catalyst surface, reducing its density and viscosity. After the washing oil detaches from the catalyst surface, it is discharged into the bottom hopper of the first centrifugal scrubber through the teardrop-shaped openings on the drum shell under centrifugal force, achieving liquid-solid separation. The waste oil generated during separation is returned to the washing oil tank for recycling via a three-way valve, and after a period of accumulation, it is discharged for recovery.

[0052] (2) Hot air blowing

[0053] The spent catalyst after primary washing is fed into a second centrifugal scrubber via a first screw conveyor. Inside the second centrifugal scrubber, preheated nitrogen or dry air is introduced to purge the catalyst, continuously vaporizing the residual washing oil on the catalyst surface, further removing oil contamination from the spent catalyst and generating oily exhaust gas. The purified catalyst is then unloaded and recycled as described in step (1).

[0054] (3) Gas-liquid separation and recovery

[0055] Oily waste gas generated after purging with nitrogen or dry air enters the stripping waste gas buffer tank through the gas phase outlet of the second centrifugal scrubber shell. As the temperature naturally cools down, the scrubbing oil entrained in the gas phase condenses into droplets, which are captured and separated by the fiber coalescing internals at the top of the buffer tank, thus obtaining clean cooling gas and waste oil, which are sent downstream for recycling respectively.

[0056] This invention also provides a centrifugal washing and oil removal device for oily waste catalysts, the device comprising:

[0057] This invention provides a centrifugal washing and oil removal device for oily waste catalysts. The main equipment of the device includes:

[0058] The feed cantilever elevator 101 is used to transport the waste catalyst slurry discharged from each oil refining unit from the transport vehicle to the top of the closed conveyor belt, serving as the starting point for feeding the waste catalyst of the entire centrifugal washing and separation unit.

[0059] The first hopper feeder 102, which is connected to the feeding cantilever elevator 101, is the key channel for the waste catalyst to enter the centrifugal scrubber. It works with a motor-driven closed conveyor belt and relies on the gravity of the catalyst slurry itself to automatically feed the waste catalyst.

[0060] A first centrifugal scrubber 103, connected to the first hopper feeder 102, is used to perform primary centrifugal washing of the catalyst slurry from the first hopper feeder 102. Simultaneously, washing oil is injected into the first centrifugal scrubber 103 via a washing oil pump 106. Fresh or recycled washing oil comes from the washing oil tank 107. After primary centrifugal washing, the washing oil dissolves the residual oil or wax oil on the catalyst surface to form a mixed oil. This mixed oil enters the bottom hopper 22 of the first centrifugal scrubber through the drain holes 36 on the outer wall 34 of the first centrifugal scrubber drum and is then returned to the washing oil tank 107 for recycling.

[0061] The second hopper feeder 109, connected to the bottom hopper 22 of the first centrifugal washer, drives the first screw conveyor 108 to send the catalyst particles after primary oil washing into the second centrifugal washer 110 via a motor.

[0062] The second centrifugal scrubber 110, connected to the second hopper feeder 109, is used for secondary centrifugal washing of the catalyst particles from the second hopper feeder 109, removing residual oil and washing oil from the catalyst surface via hot gas stripping. The purge gas comes from the utility system and is heated to a preset temperature by the preheater 111 before entering the second centrifugal scrubber 110. After stripping, the catalyst is discharged into the bottom hopper 22 of the second centrifugal scrubber and then discharged and recovered via the second screw conveyor 112. The oily waste gas enters the stripping waste gas buffer tank 113 through the gas phase outlet of the outer shell of the second centrifugal scrubber 110.

[0063] The stripping waste gas buffer tank 113, connected to the gas phase outlet of the second centrifugal scrubber 110, is used to remove oil droplets from the oily waste gas from the second centrifugal scrubber 110. Through natural cooling and settling of the gas phase inside the buffer tank, the washing oil condenses into droplets and is captured and separated by the fiber coalescing internals 114 at the top of the buffer tank, resulting in clean cooling gas and waste oil, which are then sent to the downstream collection system for recycling.

[0064] The two-stage centrifugal scrubbers in the device are both horizontal in structure. The centrifugal scrubbers are designed independently according to hydraulic parameters and are equipped with internal components such as a drum axial baffle 35, a drain hole 36, a high-efficiency spray system 4, and a backwash pipe 43. A drain guide is provided on one side of the bottom of the cylindrical body 21 of the outer shell to prevent liquid accumulation inside the outer shell 2 after shutdown backwashing.

[0065] In the aforementioned device, the number of nozzles 42 on the feed pipe 41 of the spray system 4 is 24 to 60. The nozzles 42 are selected based on the oil content of the waste catalyst, preferably one of the following: spiral atomizing nozzle, built-in twisted blade nozzle, or straight nozzle. The entire centrifugal washing and separation system is remotely controlled by DCS to achieve automated operation with human-machine separation. The washing oil pump 106 in the device is an explosion-proof metering diaphragm pump.

[0066] The fiber coalescing inner part 114 at the top of the gas stripping waste gas buffer tank 113 adopts a double helix heterogeneous fiber mixed inner part or a combination of inclined corrugated plate and heterogeneous fiber mixed inner part to improve the gas-liquid separation effect.

[0067] The following is based on the appendix Figure 3 ~5. Detailed description of the centrifugal washer structure design of the present invention.

[0068] Figure 3 This is a three-dimensional structural diagram of a centrifugal washer designed independently according to an embodiment of the present invention. As shown in the figure, this device uses an LXXD-1000 (drum diameter parameter) centrifugal washer, which consists of several main components such as frame 1, outer shell 2, drum assembly 3, spray system 4, and transmission system 5.

[0069] The frame 1 primarily serves to support and stabilize the centrifugal washer. The outer casing 2 mainly consists of a cylindrical body 21 and a bottom hopper 22, providing load-bearing support for the drum assembly 3 and the transmission system 5, and also providing safety protection. The outer casing 2 is positioned above the frame 1, and the two are fixed together by welding or bolts.

[0070] The transmission system 5 is located on one side of the frame 1 and the outer casing 2, coaxial with the drum assembly 3; the spray system 4 passes through the outer casing 2 and extends into the drum assembly 3, with a distance of 50-200mm between it and the inner side of the outer wall 34 of the drum; the drum assembly 3 is centrally located, and its main shaft 33 is connected to the transmission system 5 via a coupling 53, providing rotational power to the drum. The motor drive force is controlled by a frequency converter, which can be arbitrarily adjusted within the frequency range of 0-60Hz, thereby achieving stepless speed regulation of the motor within the range of 0-200r / min.

[0071] Figure 4This is a three-dimensional schematic diagram of the internal structure of a centrifugal washer drum, designed independently according to an embodiment of the present invention. As shown in the figure, the drum assembly 3 mainly includes three parts: the drum body 31, the electric opening device 32, and the main shaft 33. The electric opening device 32 is used to open the drum during automatic feeding of waste catalyst, and the power source is either an electro-hydraulic type or an electric guide rail type. The main shaft 33 is generally forged from 45# steel; however, this invention uses 316L stainless steel to meet the compatibility principle of the washing oil. The drum body 31 consists of several parts, including the drum outer wall 34, axial baffles 35, and drainage holes 36. The drum outer wall 34 is coaxially fixed to the main shaft 33, and the axial baffles 35 are evenly distributed on the inner side of the drum outer wall 34, promoting mixing and mass transfer. The outer wall 34 of the drum is made of high-strength stainless steel 2205. The outer wall 34 of the drum and the spray system 4 connected to the other side have dynamic balance design requirements, generally requiring an accuracy of 6.3 or above to ensure smooth operation and low noise. The number of axial baffles 35 inside the drum is 6 to 12, with a thickness of 5 to 20 mm and a length consistent with the length of the drum body 31. The diameter of the drain tear hole 36 is 1 to 5 mm, and the opening rate is 20% to 40% of the unfolded surface of the outer wall 34 of the drum.

[0072] Figures 5(a) to (b) are schematic diagrams of the internal structure and nozzle arrangement of a centrifugal scrubber sprayer designed according to an embodiment of the present invention. As shown in the figures, by optimizing the nozzle type and drum speed according to process requirements, the effect of centrifugal vortex inside the drum is minimized, backmixing is reduced, and forced shearing and breaking of droplets are achieved. This results in better liquid-liquid or gas-liquid mass transfer at a lower drum speed and prevents severe emulsification of the mixed solution. Preferably, the circumferential arrangement angle θ of the nozzle 42 on the detergent feed pipe 41 is 60° to 90°.

[0073] Example

[0074] The present invention is further illustrated below with reference to specific embodiments. However, it should be understood that these embodiments are for illustrative purposes only and do not constitute a limitation on the scope of the invention. Test methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages and parts are by weight.

[0075] Example 1:

[0076] A chemical research institute in Dalian conducted pilot-scale tests using the method and apparatus of this invention to treat spent catalyst from hydroreform residue oil. Figure 1The waste catalyst centrifugal washing and separation method described herein involves process design and development of a related centrifugal washer. After treatment, relatively pure waste catalyst particles, diesel oil, and a mixed solution of residual oil are recovered. The process generates no wastewater or waste residue, achieving resource recovery and generating significant economic benefits. The specific operation process and effects are as follows:

[0077] (1) Test conditions

[0078] The composition of the catalyst to be treated is basically as follows: the total mass of the waste catalyst slurry is approximately 694.4 kg, of which the mass of the waste catalyst is approximately 520.8 kg, and the oily substance is mainly residual oil with an oil content of 25%, weighing approximately 173.6 kg, with an oil phase density of 1.0–1.1 g / cm³. 3 Viscosity of 1000-1200 mm 2 / s, with catalyst particle size ranging from 2 to 8 mm;

[0079] Centrifugal washer design parameters:

[0080] Model: Self-designed LXXD-1000, 2 units, two-stage series operation;

[0081] Drum speed: 50 r / min, speed controlled by frequency converter;

[0082] Mixing flux: 2.5m 3 / h;

[0083] Main unit power: 0.75kW;

[0084] External dimensions: 2000×2000×2600mm;

[0085] Operating parameters: Considering that a batch of waste catalyst slurry is processed every hour, the total feed flow rate is about 700L / h, the circulation rate of the first-stage washing oil is about 350L / h, and the feed rate of the second-stage nitrogen is about 1150L / h, wherein the operating temperature of the nitrogen is 210~250℃.

[0086] (2) Brief description of the process flow

[0087] First, the residual oil catalyst is fed into a primary centrifugal scrubber via a closed conveyor belt, while diesel fuel is injected into it. In the primary centrifugal scrubber, the rotating drum thoroughly mixes the two phases, dissolving the residual oil on the catalyst surface and reducing its density and viscosity. Simultaneously, under centrifugal force, the wash oil detaches from the surface of the spent catalyst and flows into the hopper at the bottom of the scrubber through drainage holes on the drum surface, achieving liquid-solid separation. The separated wash oil can be recycled after filtration, while the washed spent catalyst is sent to a secondary centrifugal scrubber via a screw conveyor. In the secondary centrifugal scrubber, high-temperature nitrogen gas is introduced to purge the catalyst, causing the residual wash oil on the catalyst surface to evaporate with the nitrogen, resulting in a de-oiled catalyst. Subsequently, the nitrogen gas and the evaporated oil phase enter a buffer tank. Due to the decrease in temperature, the gaseous oil condenses into droplets, which are captured and separated by the fiber coalescing internals at the top of the buffer tank, thus obtaining clean nitrogen and waste oil, which are then sent downstream for recycling.

[0088] (3) Application effect

[0089] After treatment using this centrifugal washing and separation method and device, the experimental results show that the amount of oil phase entrained in the recovered waste catalyst is about 2.5%, and the total processing time for washing and stripping of 700 kg / batch of residual oil catalyst is 50 min. Compared with the original process, the centrifugal washing and separation technology saves about 25% of diesel fuel compared with the fluidized bed treatment technology. Part of the washing oil containing residual oil and loaded metal is recycled, and the other part is filtered through metal refining. It is estimated that about 50-80 t / a of diesel fuel can be recovered annually, which can create considerable economic value.

[0090] Example 2:

[0091] A catalyst processing workshop at a Shanghai refinery has implemented the method and apparatus of this invention in industrial applications, treating the regenerated catalyst for hydrotreated diesel fuel. Figure 1 The waste catalyst centrifugal washing and separation method described herein involves process design and development of a related centrifugal washer. After treatment, relatively pure regenerated catalyst particles, a mixed solution of kerosene and wax oil are recovered. The process generates no wastewater or waste residue, achieving resource recovery and generating significant economic benefits. The specific operation process and effects are as follows:

[0092] (1) Design conditions

[0093] The composition of the catalyst to be treated is basically as follows: the total mass of the waste catalyst slurry is approximately 833.3 kg, of which the mass of the waste catalyst is approximately 708.3 kg, and the oily substance is mainly wax oil, with an oil content of 15% and a mass of approximately 125.0 kg. The oil phase density is 0.8–0.9 g / cm³. 3 Viscosity is 120-150 mm 2 / s, the catalyst particle size range is 0.5~6mm;

[0094] Centrifugal washer design parameters:

[0095] Model: Self-designed LXXD-1200, 2 units, two-stage series operation;

[0096] Drum speed: 35 r / min, speed controlled by frequency converter;

[0097] Mixed flux: 3.0 m 3 / h;

[0098] Main unit power: 0.75kW;

[0099] External dimensions: 2400×2400×3200mm;

[0100] Operating parameters: Considering that a batch of waste catalyst slurry is processed every hour, the total feed flow rate is about 1000L / h, the circulation rate of the first-stage washing oil is about 250L / h, and the second-stage hydrogen feed rate is about 1000L / h, wherein the operating temperature of the hydrogen is 230~280℃.

[0101] (2) Brief description of the process flow

[0102] First, the regenerated catalyst is fed into a primary centrifugal scrubber via a closed conveyor belt, while kerosene is simultaneously sprayed into it. In the primary centrifugal scrubber, the rotating drum thoroughly mixes the two phases, dissolving the residual oil on the catalyst surface and reducing its density and viscosity. Simultaneously, under centrifugal force, the wash oil detaches from the surface of the regenerated catalyst and flows into the hopper at the bottom of the scrubber through drainage holes on the drum surface, achieving liquid-solid separation. The separated wash oil can be recycled after filtration, while the washed regenerated catalyst is fed into a secondary centrifugal scrubber via a screw conveyor. In the secondary centrifugal scrubber, high-temperature hydrogen gas is introduced to purge the catalyst, causing the residual wash oil on the catalyst surface to evaporate with the hydrogen, resulting in a de-oiled catalyst. Subsequently, the hydrogen and the evaporated oil phase enter a buffer tank. Due to the decrease in temperature, the gaseous oil condenses into droplets, which are captured and separated by the fiber coalescing internals at the top of the buffer tank, thus obtaining clean hydrogen and waste oil, which are then sent downstream for recycling.

[0103] (3) Application effect

[0104] After processing using this centrifugal washing and separation method and device, the sample results show that the entrainment of the regenerated catalyst oil phase is about 1.5%, and the total processing time for washing and stripping of 850 kg / batch of regenerated catalyst is 45 min. Compared with the original process, the centrifugal washing and separation technology saves about 30% of kerosene consumption compared with the cyclone separation technology. Part of the washing oil containing wax oil and loaded metal is recycled, and the other part is filtered through metal refining. It is estimated that about 30-60 t / a of kerosene can be recovered annually, which can create considerable economic value.

[0105] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A centrifugal washing and oil removal device for oily waste catalysts, characterized in that, The device includes: a cantilever elevator connected to a first hopper feeder, the bottom of the first hopper feeder connected to the top of a first centrifugal washer, a washing oil tank connected to the side inlet of the first centrifugal washer via a washing oil pump, the bottom of the first centrifugal washer connected to the washing oil tank via a three-way valve, and the other path sequentially connected to a first screw conveyor, a second hopper feeder, and a second centrifugal washer, the side inlet of the second centrifugal washer receiving purge gas from the utility system via a preheater, and the gas phase outlet of the second centrifugal washer connected to an exhaust gas buffer tank, the bottom of which is connected to a second screw conveyor, and a fiber coalescing internal component installed on the top of the exhaust gas buffer tank; The first and second centrifugal washers are horizontal centrifugal washers with identical structures, including a frame, outer shell, drum assembly, spray system, and transmission system. The outer shell is mainly composed of a cylindrical body and a bottom hopper. The outer shell is placed above the frame and the two are fixed by welding or bolts. The drum assembly is placed inside the outer shell and is arranged coaxially and centrally with the outer shell. The axial distance between the inner wall of the outer shell and the outer wall of the drum assembly is 100~500 mm. The drum assembly mainly includes a drum body, an electric opening device, and a main shaft. The electric opening device, which is used to open the drum during feeding or unloading, is powered by either an electro-hydraulic type or an electric guide rail type. The drum body consists of an outer wall, axial baffles, and drainage holes. The outer wall of the drum is coaxially arranged with the main shaft. The axial baffles are evenly distributed on the inner side of the outer wall of the drum, and the drainage holes are evenly distributed on the outer wall of the drum. The spray system includes a feed pipe, nozzles, and a backwash pipe. The nozzles are evenly distributed circumferentially on the feed pipe. The feed pipe is coaxially arranged with the drum assembly, passes through the outer shell, and extends into the drum assembly. The distance between the feed pipe and the inner side of the outer wall of the drum is 50-200 mm. The feed pipe is connected and fixed to the external pipeline through a rotary joint and is linked with the drum during operation. The backwash pipe, used to flush the drainage tear holes, is fixed to one side of the inner wall of the outer shell. The transmission system is located on one side of the frame and the outer casing, coaxial with the drum assembly. The motor is located outside the cover plate, and the coupling is connected to the motor via bearings and passes through the outer casing to be connected to the drum assembly on the same side.

2. The centrifugal washing and oil removal device as described in claim 1, characterized in that, In the centrifugal washer described above, the number of axial baffles inside the drum is 6 to 12, the thickness is 5 to 20 mm, and the length is consistent with the length of the drum body; the diameter of the drain tear hole is 1 to 5 mm, and the opening rate is 20% to 40% of the unfolded surface of the outer wall of the drum.

3. The centrifugal washing and oil removal device as described in claim 1, characterized in that, In the centrifugal scrubber, the number of nozzles on the feed pipe of the spray system is 24 to 60, and the nozzles are one of the following: spiral atomizing nozzles, built-in twisted blade nozzles, and straight nozzles; the spray pressure of the nozzles is 0.2 to 2 MPa, and the droplet size range is 50 to 500 μm; a drain is provided on one side of the bottom of the cylindrical body of the outer shell.

4. The centrifugal washing and oil removal device as described in claim 1, characterized in that, The device is remotely controlled by DCS to achieve automated operation with human-machine isolation; the centrifugal washer is set to multiple stages.

5. The centrifugal washing and oil removal device as described in claim 1, characterized in that, The electric opening device on the centrifugal washer drum assembly is either an embedded electric skylight on the outer wall of the drum or a guide rail type semi-open drum body.

6. The centrifugal washing and oil removal device as described in claim 1, characterized in that, The fiber coalescing inner part at the top of the exhaust gas buffer tank is a double-helix heterogeneous fiber mixed inner part or a combination of oblique corrugated plate and heterogeneous fiber mixed inner part.

7. A method for centrifugal washing and oil removal of oily waste catalyst using the apparatus described in claim 1, characterized in that, The method includes the following steps: (a) Collection and transportation: First, the waste catalyst slurry is collected and transported to the top of the closed conveyor belt by a cantilever elevator. Then, it is slowly fed into the first hopper feeder by the closed conveyor belt. (b) Oil washing: Automatic feeding is achieved through the cooperation of the electric door of the first centrifugal scrubber drum, allowing the slurry collected in step (a) to enter the drum area of ​​the first centrifugal scrubber. After feeding is completed, the door is closed. Washing oil is sprayed into the drum. In the first centrifugal scrubber, the rotating drum fully mixes the slurry and washing oil. The washing oil extracts oily substances that fall off the catalyst surface and, under the action of centrifugal force, are discharged into the bottom hopper of the first centrifugal scrubber through the drain hole on the drum shell, thus achieving liquid-solid separation. (c) Unloading: The washing waste oil generated in step (b) is returned to the washing oil tank for recycling through a three-way valve. Whether to discharge and recycle is determined according to the saturation of the washing oil. During operation, the system automatically replenishes fresh oil or stops the pump and shuts down according to the liquid level change in the washing oil tank. After the washing waste oil in the bottom hopper of step (b) is discharged, the position of the drum is adjusted to be directly above the bottom hopper, the electric hatch is opened, and the waste catalyst is unloaded. (d) Purging: The spent catalyst from the bottom hopper in step (c) is subjected to a two-stage centrifugal washing process. Through the switching of the three-way valve and the conveying of the first screw conveyor, the spent catalyst is sent to the drum area of ​​the second centrifugal scrubber. In the drum of the second centrifugal scrubber, hot air is introduced to purge the spent catalyst particles. The washing oil remaining on the catalyst surface is continuously vaporized by gas lifting, further removing oil stains from the spent catalyst and generating oily exhaust gas. The purified catalyst is unloaded in the manner described in step (c). The catalyst collected in the bottom hopper is then conveyed to the product recovery tank or enters the regeneration unit via the second screw conveyor. (e) Gas-liquid separation: The oily waste gas generated in step (d) enters the gas stripping waste gas buffer tank through the gas phase outlet of the second centrifugal scrubber shell. As the temperature naturally cools down, the washing oil entrained in the gas phase condenses into droplets and is captured and separated by the fiber coalescing internals at the top of the buffer tank, obtaining clean cooling gas and waste oil, which are sent to the downstream collection system for recycling.

8. The centrifugal washing and oil removal method as described in claim 7, characterized in that, The washing oil used for oil washing is one of the following: catalytic gasoline, catalytic diesel, hydrogenated gasoline, hydrogenated diesel, kerosene, topping oil, and residual oil. The oil washing time is 15-30 minutes. The purging gas is selected from nitrogen or dry air. The purging time is 20-40 minutes.

9. The centrifugal washing and oil removal method as described in claim 7, characterized in that, In step (b), the flow ratio of the waste catalyst to the washing oil entering the first centrifugal scrubber is 2:1 to 4:1, the pressure drop is 0.05 to 0.2 MPa, and the washing oil flow rate is 0.25 to 1.5 m / s. The waste catalyst discharged in step (c) is a vacuum residue catalyst with an oil content of 20-30% and an oil phase density of 1.0-1.1 g / cm³. 3 Viscosity of 1000~1200 mm 2 / s, with catalyst particle size ranging from 2 to 8 mm; Alternatively, the waste catalyst discharged in step (c) can be a regenerated catalyst with an oil content of 10-20% and an oil phase density of 0.8-0.9 g / cm³. 3 Viscosity is 120~150 mm 2 / s, with catalyst particle size ranging from 0.5 to 6 mm; In step (d), the flow ratio of the waste catalyst entering the second centrifugal scrubber to the purge gas is 1:1 to 1:3, the purge gas stripping preheating temperature is 230℃ to 370℃, the inlet pressure is 8.5 MPa to 18 MPa, the pressure drop is 0.5 to 5 MPa, and the purge gas flow rate is 30 to 80 mm / s.

10. The centrifugal washing and oil removal method as described in claim 7, characterized in that, Before the waste washing oil generated in step (c) enters the washing oil tank, a pipeline filter is installed, and the frequency of circulating waste oil discharge is determined according to the backwashing frequency of the filter. At the same time, after the circulating waste oil is discharged, fresh washing oil is added to the washing oil tank. The amount of replenishment must ensure that the flow ratio of waste catalyst to washing oil entering the first centrifugal scrubber remains unchanged at 2:1 to 4:1.

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