Pretreatment process for waste catalyst recovery

Abstract

The invention belongs to the technical field of catalyst recovery, and particularly relates to a pretreatment process for waste catalyst recovery, which comprises the following steps: continuously and hermetically conveying raw materials into a pyrolysis cavity of an indirect pyrolysis furnace; a combustor at the bottom of the indirect pyrolysis furnace is started, heat is transferred into a pyrolysis cavity, the raw materials are continuously heated in the pyrolysis cavity isolated from oxygen, moisture and oil gas in the raw materials are evaporated, pyrolysis gas is discharged, and a solid phase obtained after pyrolysis is discharged into the rotary direct pyrolysis furnace; a combustor at the end part of the rotary direct pyrolysis furnace is started, flame and high-temperature flue gas are in direct contact with a pyrolyzed solid phase for heating, further oxidation and decomposition are performed in a continuous high-temperature environment, and a pyrolysis product is obtained. Oil in the raw materials is reasonably utilized, heat value loss is reduced, energy is saved, and meanwhile the process is simplified.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst recovery, and in particular relates to a pretreatment process for recovering waste catalysts. Background Art

[0002] HW50 waste catalyst generated in the manufacture of refined petroleum products contains valuable metals such as vanadium, molybdenum, and nickel, and has a relatively high recovery value.

[0003] This waste catalyst material contains oil and organic matter, accounting for up to 30%, and needs to be pre-treated by pyrometallurgical process, and then the valuable metals are extracted by wet process. The conventional method is to use a rotary kiln to roast the material at high temperature to directly remove the oil and organic matter inside, and add sodium carbonate to convert molybdenum and vanadium into soluble salts.

[0004] This method has two disadvantages. The first is that because the calorific value of this oil-containing material is relatively high, direct roasting will cause the temperature in the kiln to exceed the process requirements, causing a "ringing" phenomenon, affecting normal production and causing a waste of heat energy. The second is that the local temperature is too high, resulting in uneven roasting effects, affecting the conversion of molybdenum and vanadium.

[0005] In the past, some manufacturers have carried out de-oiling pretreatment, which is an intermittent operation mode and requires changing the work place. Dust and smoke are generated during the operation, and heat energy is seriously wasted. This method has basically been eliminated.

[0006] Recently, a patent (application number: CN202011005238.5) has proposed a method for low-temperature thermal degreasing, which can be operated continuously and automatically. The patent has carried out secondary degreasing, separated the oil in the material more thoroughly, and collected it, but did not treat the residual organic matter in the material. The rotary kiln is still needed to roast the organic matter, and then sodium carbonate is added to convert molybdenum and vanadium into soluble salts. It is not necessary to completely separate the oil in the material in the above method, because the subsequent roasting treatment still requires heat energy, and it is sufficient to remove the oil to about 15%; in addition, the deoiled material needs to be water-cooled and temporarily stored for subsequent roasting treatment, which wastes a lot of heat energy in the middle, and the process is not simplified.

[0007] Therefore, technicians in this field have proposed a new process for waste catalyst recovery and pretreatment to solve the problems arising from the above technical background. Summary of the invention

[0008] The purpose of the present invention is to provide a pretreatment process for waste catalyst recovery, which overcomes the shortcomings of the prior art and adopts a treatment method of primary indirect pyrolysis oil removal and secondary direct pyrolysis organic matter removal, rationally utilizes the oil present in the raw materials, reduces calorific value loss, saves energy, and simplifies the process.

[0009] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0010] A pretreatment process for waste catalyst recovery comprises the following steps:

[0011] S1. Feeding and conveying: conveying the raw materials continuously and sealed into the pyrolysis chamber of the indirect pyrolysis furnace;

[0012] S2. Indirect pyrolysis treatment: Start the burner at the bottom of the indirect pyrolysis furnace to transfer heat to the pyrolysis chamber, and continuously heat the raw materials in the pyrolysis chamber isolated from oxygen to evaporate the moisture and oil gas in the raw materials, discharge the pyrolysis gas, and discharge the solid phase after pyrolysis to the rotary direct pyrolysis furnace;

[0013] S3. Direct pyrolysis treatment: Start the burner at the end of the rotary direct pyrolysis furnace. The flame and high-temperature flue gas are in direct contact with the pyrolyzed solid phase for heating. The solid phase is further oxidized and decomposed under a continuous high-temperature environment to obtain pyrolysis products.

[0014] Furthermore, the raw materials described in S1 are conveyed to a feeding hopper through a sealed conveyor, and then conveyed to a bucket elevator through a screw conveyor at the bottom of the feeding hopper, and then conveyed to an indirect pyrolysis furnace through the bucket elevator.

[0015] Furthermore, an air locking mechanism is provided at the inlet / outlet of the pyrolysis chamber in S2 to isolate the oxygen in the pyrolysis chamber. A flow guiding mechanism and a stirring mechanism are provided inside the pyrolysis chamber. The flow guiding mechanism is used to guide the discharge of the solid phase after indirect pyrolysis, and the stirring mechanism is used to stir the raw materials of indirect pyrolysis to prevent coking at the bottom of the raw materials.

[0016] Furthermore, a plurality of induced draft fans are connected to the outer side of the pyrolysis chamber in S2 for extracting the pyrolysis gas generated by the indirect pyrolysis to the condensation recovery section.

[0017] Furthermore, the condensation recovery section includes a spray condenser and an oil-water separator. The spray condenser sprays the pyrolysis gas by spraying circulating condensed water, and the condensed oil-water mixture is transported to the oil-water separator. The oil-water separator is used to settle and separate the oil-water mixture, and the separated water is transported to the spray condenser as condensed water, and the separated oil is transported to the burner at the end of the rotary direct pyrolysis furnace as fuel.

[0018] Furthermore, the temperature in the pyrolysis chamber in S2 is not higher than 400°C, and the temperature in the rotary direct pyrolysis furnace in S3 is not higher than 700°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention optimizes the pretreatment process by adopting the method of primary indirect pyrolysis oil removal and secondary direct pyrolysis organic matter removal, realizes continuous automation of the pretreatment process, makes the process more coherent and smooth, reduces the work intensity of workers, reduces the leakage of dust and smoke, and improves the working environment.

[0021] The present invention adds a condensation recovery section after the first-level indirect pyrolysis deoiling to recover the oil in the pyrolysis gas and use it as fuel for the second-level direct pyrolysis. The first-level indirect pyrolysis deoils to 15%, and the remaining oil can also be used as fuel to provide thermal energy, thereby reducing calorific value loss and saving energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a process equipment flow chart of a pretreatment process for waste catalyst recovery. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, the pretreatment process for waste catalyst recovery described in the present invention comprises the following steps:

[0025] S1. Feeding and conveying: conveying the raw materials continuously and sealed into the pyrolysis chamber of the indirect pyrolysis furnace;

[0026] The raw materials are transported to the hopper through a sealed conveyor, and then transported to the bucket elevator through the screw conveyor at the bottom of the hopper, and then transported to the indirect pyrolysis furnace through the bucket elevator.

[0027] S2. Indirect pyrolysis treatment: Start the burner at the bottom of the indirect pyrolysis furnace to transfer heat to the pyrolysis chamber, and continuously heat the raw materials in the pyrolysis chamber isolated from oxygen to evaporate the moisture and oil gas in the raw materials, discharge the pyrolysis gas, and discharge the solid phase after pyrolysis into the rotary direct pyrolysis furnace; the temperature in the pyrolysis chamber is not higher than 400°C.

[0028] A combustion chamber is arranged at the bottom of the indirect pyrolysis furnace, and multiple burners are arranged in the combustion chamber. Natural gas is introduced to ignite the burners to heat the pyrolysis chamber, and the heat is transferred to the raw materials in the pyrolysis chamber through the outer wall of the pyrolysis chamber. Since air locking mechanisms are arranged at the inlet / outlet of the pyrolysis chamber, the raw materials are decomposed in the pyrolysis chamber in an anaerobic environment. A flow guide mechanism and a stirring structure are arranged inside the pyrolysis chamber, and the raw materials are heated, stirred and transported to the rear end in the anaerobic environment of the pyrolysis chamber.

[0029] A plurality of induced draft fans are connected to the outside of the pyrolysis chamber to draw the pyrolysis gas generated by the indirect pyrolysis to the condensation recovery section.

[0030] The pyrolysis gas is mainly composed of water vapor, oil vapor, volatile organic hydrocarbons and a small amount of dust; the condensation recovery section includes a spray condenser and an oil-water separator. The spray condenser sprays the pyrolysis gas by spraying circulating condensed water, and the condensed oil-water mixture is transported to the oil-water separator. The oil-water separator is used to settle and separate the oil-water mixture, and the separated water is transported to the spray condenser as condensed water, and the separated oil is transported to the burner at the end of the rotary direct pyrolysis furnace as fuel.

[0031] S3. Direct pyrolysis treatment: Start the burner at the end of the rotary direct pyrolysis furnace. The flame and high-temperature flue gas are in direct contact with the pyrolyzed solid phase for heating. Further oxidation and decomposition are carried out under a continuous high-temperature environment to obtain pyrolysis products. The pyrolysis products fall from the tail into the screw conveyor and directly enter the subsequent rotary kiln roasting section. The temperature in the rotary direct pyrolysis furnace is not higher than 700°C.

[0032] The burners of the indirect pyrolysis furnace and the rotary direct pyrolysis furnace are both connected to the exhaust gas treatment system through the induced draft fan, and the exhaust gas treatment system is used to treat the high-temperature flue gas generated by the combustion.

[0033] In order to ensure the safety during the treatment process, the equipment is equipped with a gas online monitoring system to conduct real-time monitoring of the oxygen content in the equipment and the combustible gas around the equipment. The equipment is also equipped with a nitrogen protection device.

[0034] The process equipment adopts a central integrated control system, which can realize remote adjustment of control parameters, reading of operating status, viewing of alarm information, calling of operating parameters and other operations as well as remote video monitoring.

[0035] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A pretreatment process for waste catalyst recovery, characterized in that: The following steps are involved: S1. Feeding and conveying: conveying the raw materials continuously and sealed into the pyrolysis chamber of the indirect pyrolysis furnace; S2. Indirect pyrolysis treatment: Start the burner at the bottom of the indirect pyrolysis furnace to transfer heat to the pyrolysis chamber, and continuously heat the raw materials in the pyrolysis chamber isolated from oxygen to evaporate the moisture and oil gas in the raw materials, discharge the pyrolysis gas, and discharge the solid phase after pyrolysis to the rotary direct pyrolysis furnace; S3. Direct pyrolysis treatment: Start the burner at the end of the rotary direct pyrolysis furnace. The flame and high-temperature flue gas are in direct contact with the pyrolyzed solid phase for heating. The solid phase is further oxidized and decomposed under a continuous high-temperature environment to obtain pyrolysis products.

2. A pretreatment process for waste catalyst recovery according to claim 1, characterized in that: The raw materials described in S1 are transported to the feeding hopper through a sealed conveyor, and then transported to the bucket elevator through a screw conveyor at the bottom of the feeding hopper, and then transported to the indirect pyrolysis furnace through the bucket elevator.

3. A pretreatment process for waste catalyst recovery according to claim 1, characterized in that: The inlet / outlet of the pyrolysis chamber in S2 is provided with an air locking mechanism for isolating the oxygen in the pyrolysis chamber. The interior of the pyrolysis chamber is provided with a flow guiding mechanism and a stirring mechanism. The flow guiding mechanism is used to guide the discharge of the solid phase after indirect pyrolysis, and the stirring mechanism is used to stir the raw materials of indirect pyrolysis to prevent coking at the bottom of the raw materials.

4. A pretreatment process for waste catalyst recovery according to claim 1, characterized in that: The outer side of the pyrolysis chamber in S2 is connected to a plurality of induced draft fans for extracting the pyrolysis gas generated by the indirect pyrolysis to the condensation recovery section.

5. A pretreatment process for waste catalyst recovery according to claim 4, characterized in that: The condensation recovery section includes a spray condenser and an oil-water separator. The spray condenser sprays the pyrolysis gas by spraying circulating condensed water. The condensed oil-water mixture is transported to the oil-water separator. The oil-water separator is used to settle and separate the oil-water mixture. The separated water is transported to the spray condenser as condensed water, and the separated oil is transported to the burner at the end of the rotary direct pyrolysis furnace as fuel.

6. A pretreatment process for waste catalyst recovery according to claim 1, characterized in that: The temperature in the pyrolysis chamber in S2 is not higher than 400°C, and the temperature in the rotary direct pyrolysis furnace in S3 is not higher than 700°C.

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