High-pressure screw feeder and system

Abstract

The high-pressure screw feeder system comprises a screw feeder main body which is driven by a variable frequency motor and realizes reliable sealing of high-pressure gas through a composite sealing assembly and a pressure balancing assembly, and an intelligent feeding system which integrates a sending tank, a weighing sensor and a PLC (Programmable Logic Controller), through a closed-loop control algorithm based on the fixed volume of the spiral groove and real-time weight feedback, the rotating speed of the motor is accurately calculated and adjusted to achieve constant-quantity or on-demand feeding, and in combination with signal linkage of gasification equipment for the rear end, the problems of poor sealing reliability and low feeding control precision under the high-pressure working condition are effectively solved; and stable and accurate high-pressure powder and particle material conveying is achieved.

Description

Technical Field

[0001] This invention relates to the field of high-pressure conveying technology for solid materials, and in particular to a high-pressure screw feeder and system. Background Technology

[0002] High-pressure screw feeders are widely used in chemical, energy (such as biomass gasification), and metallurgical industries to transport powdery or granular materials from atmospheric or low-pressure environments to high-pressure reaction vessels. Existing high-pressure screw feeders typically consist of a drive unit, a screw conveying mechanism, and a corresponding housing.

[0003] During operation, the machine body is filled with high-pressure gas to assist in material transport. However, this also poses challenges to the long-term operation of key components. On the one hand, the drive shaft needs to pass through the high-pressure machine body to achieve power transmission. The dynamic seal here is very important. If the seal fails, the high-pressure gas, along with material dust, will leak along the drive shaft to the chambers where external drive components (such as motors and bearings) are located. This not only causes pressure loss and affects system efficiency, but also seriously contaminates and corrodes high-precision components such as drive shaft support bearings, accelerating their wear and leading to increased equipment failure rate and significantly higher maintenance costs. On the other hand, in continuous production processes such as biomass gasification, the downstream reactor has precise and potentially dynamically changing requirements for the material input rate. Traditional feeding systems often rely on the operator's experience or simple open-loop speed regulation, which cannot automatically calculate the optimal screw shaft speed based on real-time material inventory and precise consumption requirements. This results in large fluctuations in the feeding rate, either mismatching with downstream requirements and affecting reaction stability, or causing material accumulation or interruption, making it difficult to achieve high-precision, predictable, and constant-volume delivery.

[0004] Therefore, in response to the problems mentioned above, the present invention proposes a high-pressure screw feeder and system. Summary of the Invention

[0005] To overcome the problems of insufficient reliability of the high-pressure dynamic seal at the drive shaft of existing high-pressure screw feeders, which easily leads to gas and dust leakage and damage to precision drive components, and the coarse control of the feeding rate, and the inability to automatically calculate and adjust the speed according to the precise demand to achieve constant and accurate feeding, this invention proposes a high-pressure screw feeder and system. This solution effectively isolates high-pressure gas and dust by designing a special sealing component with multi-layer sealing and pressure balancing structure; and integrates a PLC intelligent control system based on weight feedback and demand calculation, which can accurately calculate and adjust the drive speed according to the target conveying volume and real-time material weight, thereby achieving stable, reliable sealing and precise and controllable conveying operation under high pressure.

[0006] The technical solution of this invention is: a high-pressure screw feeder, comprising:

[0007] A variable frequency motor is used to drive the screw feeder. The variable frequency motor is fixedly connected to a drive shaft housing. The other end of the drive shaft housing is fixedly connected to the screw feeder body. The upper end of the screw feeder body is provided with a feed inlet, and the other end of the screw feeder body is provided with an air inlet and a discharge outlet. A screw shaft is provided inside the screw feeder body. A driven shaft housing is fixedly connected to the end face of the screw feeder body. A driven shaft is provided inside the driven shaft housing. A pin is provided on the end face of the driven shaft. The driven shaft is fixedly connected to the screw shaft through the pin. The output shaft of the variable frequency motor is equipped with a flat key, which is fixedly connected to the tapered sleeve coupling. The other end of the tapered sleeve coupling is fixedly connected to the drive shaft. The drive shaft passes through the drive shaft housing and is embedded in the screw feeder body, while its end face is fixedly connected to the screw shaft. A sealing assembly is provided on the surface of the drive shaft inside the screw feeder body. The sealing assembly includes a sealing gasket embedded in the end face of the screw feeder body, a cover plate fixed to the surface of the sealing gasket by a third bolt, a high-pressure dynamic sealing device embedded in the cover plate, and a sealing O-ring provided on the surface of the drive shaft. A pressure balancing assembly is installed inside the drive shaft housing and the driven shaft housing.

[0008] Preferably, the drive shaft housing is fixedly connected to the variable frequency motor housing by a first bolt, the drive shaft housing is fixedly connected to the screw feeder body by a second bolt, and the drive shaft is fixedly connected to the screw shaft by a fourth bolt.

[0009] Preferably, the sealing assembly is used to prevent high-pressure gas inside the screw feeder body from entering the drive shaft housing.

[0010] Preferably, a mounting gasket is fixedly connected inside the drive shaft housing, and the mounting gasket is fixedly connected to the sealing gasket by bolts.

[0011] Preferably, the pressure balancing assembly includes a balancing air inlet disposed inside the driven shaft housing, and a pressure balancing pipe connecting the balancing air inlet and the driven shaft housing.

[0012] This invention proposes a high-pressure screw feeder system, comprising: The feeding tank has a discharge port at its bottom, which is sealed to the inlet of the high-pressure screw feeder; The high-pressure gas source device is connected to the high-pressure gas nozzle installed in the sending tank through a pipeline. It is used to introduce high-pressure gas of 2-6MPa into the sending tank to prevent biomass pellets from stacking. It includes an air compressor unit, a gas storage tank and a pressure regulating valve. A weighing sensor is installed on the shipping tank to detect the weight of the material inside the shipping tank in real time. The PLC control system is connected to the variable frequency motor and the weighing sensor. The PLC control system is also connected to a user input interface or a remote control terminal to receive the daily total conveying parameters set by the user and to display the current conveying rate, cumulative conveying volume and variable frequency motor operating status in real time. The gasification reactor is connected to the outlet in an airtight manner. The PLC control system is also connected to the material demand signal output terminal of the gasification reactor to adjust the speed of the variable frequency motor according to the real-time material demand of the gasification reactor. The PLC control system includes: Receive material weight data detected by the weighing sensor; The target speed of the variable frequency motor is calculated based on the preset daily total conveying target value, the fixed volume of each spiral space of the spiral shaft and the material density. The variable frequency motor is controlled to run at the target speed to achieve an adjustable constant feed rate of 100-220 tons per day.

[0013] The beneficial effects of this invention are: 1. This invention constructs a composite sealing assembly including a sealing gasket, a high-pressure dynamic sealing device, and a sealing O-ring, and combines it with a pressure balancing assembly that connects the drive and driven shaft housings and introduces slightly positive pressure clean gas. This forms a dual protection mechanism of active sealing and passive isolation, effectively preventing the leakage of high-pressure process gas and material dust into the transmission component chamber. It creates a clean and low-pressure differential stable operating environment for high-precision components such as core bearings, thereby significantly improving the reliability, stability, and service life of the equipment under high-pressure and harsh operating conditions.

[0014] 2. This invention introduces a PLC intelligent control strategy based on target conveying capacity, fixed volume of the spiral groove, and real-time material weight feedback. This transforms extensive speed control into precise quantitative calculation and closed-loop adjustment, realizing a shift from experience-driven to model- and data-driven approaches. This enables the high-pressure screw feeder to stably output the preset material quantity with extremely high precision (average error controllable within ±0.1%), solving the problem of large fluctuations in feeding rate and mismatch with backend demand in traditional methods, and achieving on-demand feeding. Attached Figure Description

[0015] Figure 1 The diagram shown is a top view of the cross-sectional structure of the present invention; Figure 2 The diagram shown is a frontal cross-sectional view of the present invention. Figure 3 The diagram shown is a schematic representation of the sealing assembly structure of the present invention; Figure 4 The diagram shown is a schematic representation of the system framework of this invention.

[0016] Explanation of reference numerals in the attached drawings: 1. Variable frequency motor; 2. Drive shaft housing; 201. First bolt; 202. Flat key; 203. Tapered sleeve coupling; 204. Drive shaft; 205. Balance air inlet; 206. Second bolt; 3. Screw feeder body; 301. Screw shaft; 302. Sealing gasket; 303. High-pressure dynamic sealing device; 304. Third bolt; 305. Cover plate; 306; 307; 308. Mounting gasket; 309. Driven shaft housing; 310. Driven shaft; 311. Air pressure balance pipe; 312. Pin; 4. Feed inlet; 5. Air inlet; 6. Discharge outlet. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figures 1-3 The present invention provides an embodiment of a high-pressure screw feeder: The housing of the variable frequency motor 1 is rigidly connected to one end of the drive shaft housing 2 via arrayed first bolts 201, thereby ensuring the stability and coaxiality of the connection between the power source and the transmission mechanism. The output shaft of the variable frequency motor 1 extends into the interior of the drive shaft housing 2, on which a keyway is machined, and is connected to the inner tapered sleeve of the tapered coupling 203 via a flat key 202. The other end of the tapered coupling 203 is fixed to the drive shaft 204 via the same tapered sleeve structure. The drive shaft 204, as the core transmission rod, passes through the drive shaft housing 2 and finally extends into the internal cavity of the screw feeder body 3.

[0019] The screw feeder body 3 is a hollow tubular structure with a feed inlet 4 at its top for receiving material from upstream equipment (such as a delivery tank); a discharge outlet 6 at its tail (away from the drive end) for discharging the material conveyed to the end; in addition, an air inlet 5 is provided on the side or top of the tail of the body 3 to introduce high-pressure gas into the body, creating a propulsive force and fluidization environment for material conveying. Inside the body 3, a screw shaft 301 is installed parallel to its axis, extending from the drive end to the driven end. Continuous helical blades are welded or integrally formed on the shaft. The pitch and diameter of the helical blades are precisely calculated to ensure that the geometric volume of each helical groove (i.e., the closed space formed by adjacent blades and the inner wall of the machine body) is equal.

[0020] The end of the drive shaft 204 extending into the machine body 3 is connected and fixed to the end flange of the screw shaft 301 by the fourth bolt 307, thereby transmitting the rotational power of the variable frequency motor 1 to the screw shaft 301 and driving it to rotate. In the area where the drive shaft 204 passes through the end wall of the machine body 3, a multi-stage composite sealing assembly is arranged. The main body of this sealing assembly is a sealing gasket 302 embedded in a machined groove on the end face of the screw feeder machine body 3. A cover plate 305 is fastened to the outside of the sealing gasket 302 by evenly distributed third bolts 304. A precise circular hole is opened in the center of the cover plate 305, through which the drive shaft 204 passes. A high-pressure dynamic sealing device 303 is embedded in this circular hole. The high-pressure dynamic sealing device 303 is the core of the technology and can be of the form of a mechanical seal, a multi-layer stuffing box seal, or a special lip seal. Taking a double-end mechanical seal as an example, the two sealing ends are tightly fitted together under the combined action of spring and fluid pressure. On the drive shaft 204, located inside (on the machine body side) and / or outside the high-pressure dynamic sealing device 303, one or more sealing O-rings 306 are also fitted. The sealing O-rings 306 are made of materials such as fluororubber and hydrogenated nitrile rubber, which can withstand high pressure and possible material dust erosion. As an auxiliary seal, they block possible tiny leakage paths. Inside the drive shaft housing 2, a mounting gasket 308 is also fixed by bolts. This mounting gasket 308 can be connected to the sealing gasket 302 by additional bolts, providing additional support and positioning for the entire sealing assembly and enhancing its ability to resist axial forces caused by internal high pressure. This composite sealing assembly works together to tightly seal the high-pressure gas inside the screw feeder body 3, preventing it from leaking into the internal space of the drive shaft housing 2 along the drive shaft 204.

[0021] During long-term operation, minute gas infiltration or momentary fluctuations in the seals may cause a slow increase in pressure within the drive shaft housing 2 or the driven shaft housing 309. To address this, the present invention introduces a pressure balancing assembly, which includes a balancing air inlet 205 on the drive shaft housing 2. Simultaneously, within the driven shaft housing 309, the end of the screw shaft 301 is positioned and torque-transmitted to the driven shaft 310 via a pin 312. The driven shaft housing 309 is a closed structure designed to protect the internal support bearings. The pressure balancing assembly includes a pressure balancing pipe 311 connecting the balancing air inlet 205 of the drive shaft housing 2 and the driven shaft housing 309. This pipe connects the internal chambers of the drive shaft housing 2 and the driven shaft housing 309, forming a unified high-pressure (balanced with the high pressure within the screw feeder body 3) balancing chamber. Its working mechanism is that by injecting high-pressure gas into the balance air inlet 205 to balance the pressure inside the screw feeder body 3, the high-pressure gas enters the driven shaft housing 309 through the air pressure balance pipe 311, thereby achieving pressure balance at three ends and preventing damage to components due to uneven pressure.

[0022] Please see Figure 4 This embodiment proposes a high-pressure screw feeder system with an integrated intelligent control system: The system includes a high-pressure screw feeder, a feeding tank, a high-pressure air source device, weighing sensors, and a PLC control system. The feeding tank is located above the feed inlet 4 of the high-pressure screw feeder. Its bottom outlet is sealed to the feed inlet 4 via a flange or flexible connector. The feeding tank serves as a buffer and metering container for the material, and multiple high-pressure air nozzles are installed on its top or side walls. The high-pressure air source device supplies these nozzles with dry, clean gas at a stable pressure of 2-6 MPa (adjustable according to material characteristics, such as 3-4 MPa commonly used for biomass pellets) through pipelines. The high-pressure gas is injected into the bottom material layer of the feeding tank, fluidizing the biomass pellets and other materials, preventing bridging at the bottom of the tank or the discharge port, and ensuring that the material falls smoothly and uniformly into the feed inlet 4 of the screw feeder.

[0023] The weighing sensor is integrated into the support structure of the shipping tank. It measures the total weight of the shipping tank and its contents in real time and transmits the weight signal to the PLC control system. Its core control algorithm is as follows: Operators can set the target total mass of materials to be transported daily (or hourly) via a touchscreen connected to the PLC or a remote host computer. (tons / day), for example, set to 150 tons / day.

[0024] The PLC obtains fixed parameters from its own memory or through HMI input: the effective geometric volume V (cubic meters) of each spiral groove of the spiral shaft and the average bulk density ρ (tons / cubic meter) of the material. The density ρ can be an empirical constant or obtained through prior calibration.

[0025] The PLC reads the current total weight of the shipping tank from the weighing sensor in real time. And by subtracting the tare weight of the shipping can. (Already calibrated), obtain the instantaneous net weight of the material in the tank. .

[0026] Rotational speed calculation: First, calculate the target delivery rate: (tons / hour).

[0027] Then the mass rate is converted to the volume rate: (cubic meters / hour).

[0028] Then calculate the volume transported per second by a single spiral groove. The volumetric flow rate is calculated by multiplying the volume of each spiral groove V (cubic meters) by the number of revolutions per second n (revolutions / second) of the spiral shaft. Therefore, to achieve the target volumetric flow rate... The required rotational speed (rpm) of the screw shaft is: .

[0029] Finally, convert the speed unit to revolutions per minute (RPM), which is typically controlled by variable frequency motors: .

[0030] This calculation is repeated every second (or per control cycle) within the PLC, since V and ρ are constants. Proportional to .set up =150 tons / day. If ρ = 0.65 tons / cubic meter and V = 0.01 cubic meter, then the theoretical... ≈16.0 RPM.

[0031] The PLC uses the calculated target rotational speed Ntarget as a setpoint and sends a speed command to the driver of the variable frequency motor 1 via an analog output module or communication network. The variable frequency motor 1 operates precisely at the commanded rotational speed. Simultaneously, the PLC continuously monitors the weighing sensor signal. In actual operation, due to slight fluctuations in material density and changes in filling rate, the actual feeding rate may deviate slightly. The PLC can monitor these variations. The actual descent rate is compared with the theoretical descent rate, and PID (proportional-integral-derivative) fine-tuning is performed for dynamic correction. This forms a closed-loop control system that uses the actual weight consumed as feedback, ensuring that the cumulative delivery volume accurately approaches the target value within any given time period.

[0032] This invention provides a comparative example: This example compares and verifies the invention with a traditional open-loop control system (comparative example). The traditional open-loop control system requires operators to manually set a fixed frequency (speed) of the variable frequency motor based on experience, without weight feedback or daily total output target calculation.

[0033] In this example, the conveyed material is biomass pellets (density ~0.65 tons / cubic meter), and the target daily conveying capacity is set at 150 tons. After continuous operation for 7 days (168 hours), a high-precision weighing scale was installed on the receiving silo at the rear of the system's discharge port to verify the actual received volume. The results are shown in the table below.

[0034]

[0035] As shown in the table above, this invention achieves extremely high feeding accuracy and stability through a real-time calculation and adjustment strategy. The cumulative error over seven days is only -0.02 tons, and the average daily error is controlled within ±0.1%, far exceeding the traditional open-loop control method. This provides a very stable raw material input for downstream gasification or reaction processes.

[0036] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, 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 scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high pressure screw feeder, characterized by, The utility model relates to a high-pressure screw feeder, including: Driving piece for driving screw feeder to run, driving piece fixedly connected with drive shaft shell (2), the other end of drive shaft shell (2) is fixedly connected with screw feeder body (3), the upper end of screw feeder body (3) is provided with feed inlet (4), the other end of screw feeder body (3) is provided with air inlet (5) and discharge port (6), the inside of screw feeder body (3) is provided with screw shaft (301), the end surface of screw feeder body (3) is fixedly connected with driven shaft shell (309), the inside of driven shaft shell (309) is provided with driven shaft (310), the end surface of driven shaft (310) is provided with pin (312), and driven shaft (310) is fixed with screw shaft (301) through pin (312); The output shaft of the driving piece is provided with a flat key (202), which is fixed with a taper sleeve type coupling (203) through the flat key (202), the other end of the taper sleeve type coupling (203) is fixedly connected with a driving shaft (204), and the driving shaft (204) is embedded in the screw feeder body (3) through the drive shaft shell (2), and the end surface thereof is fixedly connected with the screw shaft (301); The surface of the driving shaft (204) located in the screw feeder body (3) is provided with a sealing assembly, which comprises a sealing gasket (302) embedded in the end surface of the screw feeder body (3), a cover plate (305) fixed to the surface of the sealing gasket (302) through a third bolt (304), a high-pressure dynamic sealing device (303) embedded in the cover plate (305), and a sealing O-ring (306) arranged on the surface of the driving shaft (204); A pressure balance assembly is arranged in the drive shaft shell (2) and the driven shaft shell (309).

2. A high pressure screw feeder as claimed in claim 1, characterized in that: The driving piece is a variable frequency motor (1), and the frequency of the variable frequency motor (1) is controlled to control the rotating speed.

3. A high pressure screw feeder as claimed in claim 1, characterized in that: The drive shaft shell (2) and the shell of the variable frequency motor (1) are fixedly connected through a first bolt (201), the drive shaft shell (2) and the screw feeder body (3) are fixedly connected through a second bolt (206), and the driving shaft (204) and the screw shaft (301) are fixedly connected through a fourth bolt (307).

4. A high pressure screw feeder as claimed in claim 1, characterized in that: The sealing assembly is used to prevent high-pressure gas in the screw feeder body (3) from entering the drive shaft shell (2).

5. A high pressure screw feeder as claimed in claim 1, characterized in that: The drive shaft shell (2) is fixedly connected with a mounting gasket (308), and the mounting gasket (308) is fixedly connected with the sealing gasket (302) through a bolt.

6. A high pressure screw feeder as claimed in claim 1, characterized in that: The pressure balance assembly comprises a balance air inlet (205) arranged in the driven shaft shell (309) and an air pressure balance pipe (311) connected with the balance air inlet (205) and the driven shaft shell (309).

7. A high pressure screw feeder system based on the high pressure screw feeder of claims 1-6, characterized in that, The utility model relates to a high-pressure screw feeder, including: A sending tank is provided with a discharge port at the bottom, and the discharge port is sealingly connected with the feed inlet (4) of the high-pressure screw feeder; A high-pressure gas source device is connected with the high-pressure gas nozzle arranged in the sending tank through a pipeline, and is used for introducing 2-6 MPa high-pressure gas into the sending tank to prevent biomass particles from stacking; A weighing sensor is arranged on the sending tank and is used for detecting the weight of the material in the sending tank in real time; The PLC control system is in communication connection with the variable frequency motor (1) and the weighing sensor; The PLC control system comprises: Receiving the material weight data detected by the weighing sensor; According to the preset daily delivery total amount target value, the fixed volume of each spiral space of the spiral shaft (301) and the material density, the target rotating speed of the variable frequency motor (1) is calculated; The variable frequency motor (1) is controlled to operate at the target rotating speed, so as to realize the adjustable constant feeding of 100-220 tons per day.

8. A high pressure auger system according to claim 7, wherein: The PLC control system is further connected with a user input interface or a remote control terminal, which is used for receiving the daily delivery total amount parameter set by the user and displaying the current delivery rate, the cumulative delivery amount and the operating state of the variable frequency motor (1) in real time.

9. A high pressure auger system as claimed in claim 7, wherein: The high-pressure gas source device comprises an air compressor unit, a gas storage tank and a pressure regulating valve, and the pressure regulating valve is used for stably maintaining the gas pressure output to the high-pressure gas nozzle within the range of 2-6 MPa.

10. A high pressure auger system as claimed in claim 7, wherein: The system further comprises a gasification reaction tank connected with the discharge port (6), wherein the PLC control system is further in communication connection with a material demand signal output end of the gasification reaction tank, which is used for adjusting the rotating speed of the variable frequency motor (1) according to the real-time material demand of the gasification reaction tank.

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