Combined nozzle granulation system

Abstract

The invention provides a combined nozzle granulation system. The combined nozzle granulation system comprises a granulation tower, nozzles, a feeding system and a discharging system, the spray head is a combined spray head and comprises a rotary spray head and a fixed spray disc; the rotary spray head is of a structure with two open ends, the fixed spray disc is arranged at the bottom opening of the rotary spray head and sealed, the rotary spray head is a normal-pressure spray head, the yield is adjusted through the rotating speed, the fixed spray disc is a pressure spray head, and the yield is adjusted by adjusting the pressure before spraying; the feeding system comprises a rotary spray head feeding system and a fixed spray disc feeding system, the rotary spray head feeding system and the fixed spray disc feeding system independently supply materials to the rotary spray head and the fixed spray disc respectively, and the rotary spray head and the fixed spray disc are selected to independently supply materials or supply materials in a combined mode according to the required load.

Description

Technical Field

[0001] The invention relates to the field of bisphenol A granulation. Background Art

[0002] There are two options for the bisphenol A granulation system using tower spray technology: fixed spray disc and rotating spray head. Both options have their own advantages and disadvantages. The fixed spray disc has a simple structure and requires a small tower diameter, but the output of a single spray disc is small. It is usually necessary to arrange several or even dozens of granulation spray heads in the tower at the same time. The complicated feeding system makes operation and maintenance cumbersome; the rotating spray head feeding system is simple, only one feed pipe is required and no reflux is required, but the material is sprayed out by centrifugal force, the required tower diameter is large, and a hollow belt will be formed in the granulation tower, and the space utilization rate of the granulation tower is low. Summary of the invention

[0003] The technical problem solved by the present invention is to provide a combined nozzle granulation system, which not only improves the load adjustment range of the granulation system but also improves the space utilization rate of the granulation tower by adopting a rotating nozzle combined with a fixed nozzle disc.

[0004] The technical solution of the present invention is: a combined nozzle granulation system, including a granulation tower, a nozzle, a feeding system, and a discharging system; the nozzle is a combined nozzle, including a rotating nozzle and a fixed spray disc; the rotating nozzle is a structure with openings at both ends, the fixed spray disc is arranged at the bottom opening of the rotating nozzle and is sealed, the rotating nozzle adopts a normal pressure nozzle, and the output is adjusted by the rotation speed, and the fixed spray disc is a pressurized nozzle, and the output is adjusted by adjusting the pre-spraying pressure; the feeding system includes a rotating nozzle feeding system and a fixed spray disc feeding system, the rotating nozzle feeding system and the fixed spray disc feeding system are independent feeders for the rotating nozzle and the fixed spray disc respectively, and the rotating nozzle and the fixed spray disc are selected for separate feeding or combined feeding according to the required load.

[0005] Preferably, the rotating nozzle is a conical nozzle, and the nozzle holes are horizontal straight holes.

[0006] Preferably, the opening diameter of the spray holes on the conical spray head is 0.6-1 mm, and the hole center distance is 6-9 mm.

[0007] Preferably, the fixed spray plate adopts a circular spherical arc surface structure, the opening direction is perpendicular to the spherical surface, the holes are arranged in concentric circles with equal diameters, the hole center distance is 6 to 9 mm, and the hole diameter is 0.5 to 1 mm.

[0008] Preferably, the spraying range of the fixed spray disc is controlled within 2.4m of the tower diameter center.

[0009] Preferably, a pressure regulating valve is provided in the fixed spray plate feeding system, and the pressure regulating valve is adjusted so that the pressure difference between the pressure in the granulation tower and the incoming material pressure is controlled within 26-32 KPa.

[0010] Preferably, the discharging system comprises an inverted cone arranged at the bottom center of the granulation tower, a scraper, two drop-in chutes, a screw conveyor, and a Y-shaped feeding pipe;

[0011] The material slides along the anti-cone to the circumferential ring belt; a scraper is arranged on the circumferential ring belt, and the scraper periodically sweeps the falling material into the falling chute; a screw conveyor is arranged at the bottom of the two falling chutes, the conveyor is inclined downward, and a Y-shaped conveying pipe is arranged at the discharge port to merge the two discharges into one and then send it to the downstream screening or conveying equipment.

[0012] Preferably, the cone angle of the anti-cone is greater than 60 degrees.

[0013] Preferably, the annular area outside the anti-cone at the bottom of the granulation tower adopts a flat tower bottom, and the material drop chute is opened 180 degrees.

[0014] Preferably, three working modes are set, including low-load operation mode, high-load operation mode, and combined operation mode;

[0015] The low load is a load of 10% to 13%, and only a fixed spray disc is used for feeding in the low-load operation mode. The high load is a load between 70% and 100%, and only a rotary nozzle is used for feeding in the high-load operation mode. The corresponding load in the combined operation mode is 100% to 110%, and a fixed spray disc and a rotary nozzle are used for feeding in this mode.

[0016] The beneficial effects of the present invention compared with the prior art are:

[0017] Aiming at the problems of low space utilization of granulation towers with fixed spray discs and rotary granulation nozzles and poor load regulation capability of granulation systems, the present invention adopts a combined nozzle, separate feeding and separate regulation mode to achieve wide range load regulation and higher space utilization of granulation towers.

[0018] The present invention provides a combined nozzle granulation system, wherein the combined nozzle is composed of a rotating side wall and a central fixed bottom plate, and the side wall and the bottom plate are provided with spray holes and are respectively provided with a feeding system. The rotating side wall relies on centrifugal force to throw out the bisphenol A melt to form an annular drop belt at the bottom of the tower, and the fixed bottom plate spray hole relies on pressure to spray out the bisphenol A melt to form a drop belt at the center of the bottom of the tower. An inverted cone is arranged at the center of the bottom of the granulation tower, and the inclined surface falling into the center of the tower slides along the inverted cone inclined surface to the annular bottom plate, and the bottom plate is 180 degrees apart to form a drop chute, and a downwardly inclined screw conveyor is arranged under the drop chute, and the two screw conveyor outlets convey the material to the downstream screening and conveying equipment through a Y-shaped feed pipe.

[0019] The combined nozzle of the present invention improves the space utilization rate of the granulation tower. The combined nozzle is provided with two independent feeding systems, which are independently adjusted, thereby improving the load adjustment range of the granulation system; a counter-cone is provided at the center of the bottom of the granulation tower, and the counter-cone angle is greater than 60 degrees, so as to solve the problem of material accumulation in the center of the bottom of the tower that may be caused by the central drop belt of the fixed spray plate; two screw conveyors and Y-shaped conveying pipes for conveying to the center solve the problem of material extrusion and crushing that may be caused by the excessively long transmission shaft of the screw conveyor of the large-load granulation tower and the long-distance mechanical feeding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the system;

[0021] In the figure: 1 is a fixed spray disc; 2 is a rotating nozzle; 3 is a fixed spray disc feeding system; 4 is a rotating nozzle feeding system; 5 is a granulation tower; 6 is a central reverse cone of a scraper; 7-1 is a drop chute 1 at the bottom of the granulation tower; 7-2 is a drop chute 2 at the bottom of the granulation tower; 8 is a scraper; 9-1 and 9-2 are screw conveyors; 10 is a Y-type feed pipe; 11 is a fixed spray disc pressure regulating valve; 12 is a rotating nozzle flow regulating valve; 13 is a rotating nozzle flow meter. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the embodiments.

[0023] The present invention provides a combined nozzle granulation system which is composed of a combined nozzle, a rotating nozzle feeding system, a fixed nozzle plate feeding system and a discharging system. The fixed nozzle plate and the rotating nozzle respectively use independent feeding systems, and the fixed nozzle plate and the rotating nozzle can work independently or simultaneously;

[0024] A combined nozzle is set at the top center of the granulation tower. The combined nozzle adopts a structure of a rotating nozzle and a fixed nozzle disc. The rotating nozzle adopts a conical nozzle structure, and a horizontal straight hole is opened on the side wall of the nozzle. The linear velocity and centrifugal force at the nozzle orifice determine the initial flight velocity and horizontal flight distance of the droplets. When the nozzle rotates, the molten liquid is sprayed out from the side wall spray hole. The sprayed droplets cool and solidify into solid particles during the descent process in the granulation tower and fall to the bottom of the tower. The bottom of the nozzle is a fixed spray disc. A sealing structure is set between the fixed spray disc and the rotating nozzle. The fixed spray disc is an arc-shaped spherical structure with a concentric hole on the spray disc. The spray hole angle determines the initial flight direction of the droplets, and the pre-spray pressure determines the initial flight velocity of the droplets. The molten liquid is sprayed out from the spray hole under the action of pressure, and cools and solidifies into solid particles during the descent process and falls to the bottom of the tower. A sealing ring is set between the rotating nozzle side wall and the fixed nozzle bottom to ensure that there is no leakage of the medium. The rotating nozzle adopts normal pressure nozzle, and the output is adjusted by the rotation speed. The fixed nozzle disc is a pressure nozzle, and the output is adjusted by adjusting the pre-spraying pressure.

[0025] After theoretical research and experiments, the present invention provides a preferred embodiment in which the rotating nozzle speed is 150-240rpm, the semi-cone angle range of the rotating nozzle is 8-12°, the spray hole adopts a horizontal straight hole, the row spacing of the spray holes and the hole spacing of each row are adjusted with the semi-cone angle of the nozzle and the output, and the conical nozzle has different gyration radius, side wall centrifugal pressure and linear velocity from the large end to the small end, and different opening diameters (for the bisphenol A granulation system, the average particle diameter is 1.1mm, and the opening diameter is 0.6-1mm). The molten liquid is sprayed horizontally, and the particles fall according to a parabolic trajectory, with a hole center distance of 6-9mm. The fixed spray disc adopts a circular spherical arc surface structure, the opening direction is perpendicular to the spherical surface, and the equal aperture concentric circles are arranged, the hole center distance is 6-9mm, and the aperture is 0.5-1mm. In order to ensure that the fixed spray disc spray line does not intersect with the rotating nozzle spray line, and to avoid particles colliding before condensation to cause adhesion, the spray range of the fixed spray disc is controlled within 2.4m of the tower diameter center.

[0026] The rotary nozzle feeding system is composed of a centrifugal pump, a flow regulating valve, flow, pressure, temperature measuring instruments, a reflux pipeline, etc. The molten liquid is fed into the rotary granulation nozzle on the top of the granulation tower through a centrifugal pump. The feeding pipe is equipped with temperature, pressure, flow measurement and flow regulating valves. The upper cover of the rotary nozzle is connected to the atmosphere, and the molten liquid in the nozzle is kept at normal pressure. When the flow changes, the thickness of the molten liquid film in the rotary nozzle will also change accordingly. The nozzle speed can be adjusted to make the shape of the rotating liquid surface adapt to the flow.

[0027] The fixed spray plate feeding system is composed of a centrifugal pump, a feeding pipeline, a reflux pipeline, a shut-off valve, a pressure regulating valve, a metering flow meter and corresponding temperature and pressure measuring instruments. The molten liquid is fed into the fixed spray plate on the top of the granulation tower through a centrifugal pump. The feeding pipe is equipped with a temperature, pressure, flow measurement and a pressure regulating valve. The pre-spraying pressure is controlled by the pressure regulating valve. The change of the pre-spraying pressure will cause the change of the output. In order to ensure the stability of the particle size, the pre-spraying pressure change range is controlled within the range of ±10%. When the feeding is stopped, the molten liquid flows back through the reflux pipeline.

[0028] The discharging system is composed of a central reverse cone of a scraper, a scraper arm (scraper), a 180-degree split chute, a Y-shaped feeding pipe, etc. The solidified and cooled bisphenol A particles fall to the bottom of the granulation tower. The central reverse cone area is a fixed spray plate drop belt. The material slides along the reverse cone (the cone angle is greater than 60 degrees) to the circumferential annular belt; there is a scraper on the circumferential annular belt to periodically sweep the material to the 180-degree split chute. The chute can be rectangular. A screw conveyor inclined toward the center of the circle is arranged at the bottom of the chute to deliver the material to the Y-shaped feeding pipe, and the feeding pipe is connected to a valve, screening or conveying equipment. The discharging method of the present invention adopts a combination of self-weight and mechanical discharging. The center of the bottom of the tower slides along the cone to the annular plane area under the action of its own weight, and is swept to the unloading spiral by the scraper arm.

[0029] The biggest advantage of bisphenol A granulation is that it is easy to store and transport. The molten bisphenol A can be directly fed into the resin or polycarbonation device downstream, but the molten bisphenol A is unstable and difficult to store. When the output of bisphenol A is unstable or the output of the polycarbonation or resin device changes, the bisphenol A can be stored or exported after granulation. The granulation system is operated at low load. Since the load is low, it is impossible to ensure that the side wall of the rotating granulation tube is completely covered by the molten liquid, and the traditional method is to replace the low-load rotating nozzle, otherwise a large amount of dust and uneven particles will be generated. In this scheme, only the central fixed spray disc 1 is fed when the load is low, and the molten BPA is transported to the fixed spray disc feeding system 3 by the centrifugal pump A. In order to control the pressure difference between the fixed spray disc extrusion pressure and the pressure in the granulation tower at 26-32KPa, a pressure regulating valve 11 is set after the pump, and it forms a control loop with the pressure difference in the tower and the incoming pressure to automatically stabilize the pressure difference to meet the production needs. When the granulation system increases the load or is adjusted within a larger load, and the central fixed spray disc cannot meet the requirements, the feeding system can be switched to the rotary nozzle feeding system 4, and the molten BPA is sent to the centrifugal nozzle feeding pipeline through the centrifugal pump B. The rotating speed of the rotary nozzle is adjusted according to the required output, and the material supply is controlled through the single adjustment loop formed by the flow control valve 12 and the flow meter 13 to achieve the purpose of stabilizing and adjusting the production load. When the system further increases the operating load, the load requirements can no longer be met by adjusting the rotary nozzle, and the system can be switched to the rotary nozzle and the fixed spray disc for simultaneous feeding to achieve a larger production load requirement and adjustment range.

[0030] Taking two typical working conditions of a 120,000 tons / year bisphenol granulation unit as an example, when bisphenol A / polycarbonate or bisphenol A / epoxy resin are operated jointly, most of the bisphenol A can be directly fed to the downstream polycarbonate or epoxy resin unit without granulation, and the granulation system operates at a load of 10% to 13%. At this time, only a fixed spray plate device can be used for feeding; when the polycarbonate or epoxy resin unit is shut down, all bisphenol A can be granulated and stored, and the granulation system can operate within the range of 70% to 110%, and only the rotary nozzle is used for feeding within the range of 70% to 100%; within the range of 10% to 110%, a combined operation mode is adopted. The produced bisphenol granules are stored in silos or exported. When the granulation system is shut down, the stored bisphenol A can also be used for the production of polycarbonate or epoxy resin.

[0031] The drop area of ​​the fixed spray plate is at the center of the granulation tower 5. The granular materials that fall into the center slide along the side of the scraper center anti-cone 6 to the annular drop belt, and are periodically swept into the drop troughs 7-1 and 7-2 by the scraper 8 together with the materials on the annular drop belt. The lower part of the two drop troughs is provided with screw conveyors 9-1 and 9-2, which are inclined downward, and a Y-shaped conveying pipe 10 is provided at the discharge port to merge the two discharges into one and then send them to the downstream screening or conveying equipment.

[0032] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A combined nozzle granulation system, including a granulation tower, a nozzle, a feeding system, and a discharging system; characterized in that: The nozzle is a combination nozzle, including a rotating nozzle and a fixed spray disc; the rotating nozzle is a structure with openings at both ends, the fixed spray disc is arranged at the bottom opening of the rotating nozzle and is sealed, the rotating nozzle adopts a normal pressure nozzle, and the output is adjusted by the rotation speed, and the fixed spray disc is a pressurized nozzle, and the output is adjusted by adjusting the pre-spraying pressure; the feeding system includes a rotating nozzle feeding system and a fixed spray disc feeding system, the rotating nozzle feeding system and the fixed spray disc feeding system are independent feeders for the rotating nozzle and the fixed spray disc respectively, and the rotating nozzle and the fixed spray disc are selected for separate feeding or combined feeding according to the required load.

2. The combined nozzle granulation system according to claim 1, characterized in that: The rotating nozzle is a conical nozzle, and the nozzle hole is a horizontal straight hole.

3. The combined nozzle granulation system according to claim 1, characterized in that: The opening diameter of the spray holes on the conical spray head is 0.6 to 1 mm, and the hole center distance is 6 to 9 mm.

4. The combined nozzle granulation system according to claim 1, characterized in that: The fixed spray plate adopts a circular spherical arc surface structure, the opening direction is perpendicular to the spherical surface, and the holes are arranged in concentric circles with equal diameters. The hole center distance is 6 to 9 mm and the hole diameter is 0.5 to 1 mm.

5. The combined nozzle granulation system according to claim 1, characterized in that: The spraying range of the fixed spray disc is controlled within 2.4m of the tower diameter center.

6. The combined nozzle granulation system according to claim 1, characterized in that: A pressure regulating valve is provided in the fixed spray plate feeding system, and the pressure regulating valve is adjusted so that the pressure difference between the pressure in the granulation tower and the incoming material pressure is controlled at 26-32KPa.

7. The combined nozzle granulation system according to claim 1, characterized in that: The discharging system includes an anti-cone arranged at the bottom center of the granulation tower, a scraper, two drop-in chutes, a screw conveyor, and a Y-shaped conveying pipe; The material slides along the anti-cone to the circumferential ring belt; a scraper is arranged on the circumferential ring belt, and the scraper periodically sweeps the falling material into the falling chute; a screw conveyor is arranged at the bottom of the two falling chutes, the conveyor is inclined downward, and a Y-shaped conveying pipe is arranged at the discharge port to merge the two discharges into one and then send it to the downstream screening or conveying equipment.

8. The combined nozzle granulation system according to claim 7, characterized in that: The cone angle of the anti-cone is greater than 60 degrees.

9. The combined nozzle granulation system according to claim 7, characterized in that: The annular area outside the anti-cone at the bottom of the granulation tower adopts a flat tower bottom and a 180-degree split feed chute.

10. The combined nozzle granulation system according to claim 6, characterized in that: Set three working modes, including low-load operation mode, high-load operation mode, and combined operation mode; The low load is a load of 10% to 13%, and only a fixed spray disc is used for feeding in the low-load operation mode. The high load is a load between 70% and 100%, and only a rotary nozzle is used for feeding in the high-load operation mode. The corresponding load in the combined operation mode is 100% to 110%, and a fixed spray disc and a rotary nozzle are used for feeding in this mode.

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