A belt-press continuous feeding dewatering device for straw steam explosion pretreatment

Abstract

The utility model provides a kind of straw steaming and explosion pretreatment with pressure continuous feeding dewatering device, solve screw machine filter screen easy to block, steam is easy to back surge, complex structure, machine head pressure cannot be monitored, back surge response is slow, solid material fluidity is poor and other problems.In the utility model, under the normal working condition of stable incoming material, variable-diameter screw runs normally, blowback gas structure below double-layer feeding hopper is opened periodically, machine head pressure value monitored by machine head pressure measuring device is stable, straw material is continuously conveyed in conical section cylinder and straight section cylinder, extrusion dewatering, after rubbing and refining crushing, it is sent into retainer cylinder to react;When incoming material is unstable, machine head pressure value monitored by machine head pressure measuring device suddenly decreases, feedback to anti-back-jet cylinder, anti-back-jet cylinder drives emergency blocking valve to block machine head discharge port, to prevent steam back surge.The scheme solves the problems of steam back surge and filter screen blockage, and can be applied to the industrial production of unstable incoming material of crushed plant fiber material.

Description

Technical Field

[0001] This utility model relates to the field of plant fiber raw material pretreatment technology, and in particular to a pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment. Background Technology

[0002] Screw extruders are an important piece of equipment in the pretreatment process of fermenting plant fibers such as straw to produce ethanol, sugar alcohols, etc. The screw extruder kneads, crushes, extrudes and expands the crushed, dust-removed and acid-impregnated fibrous raw materials such as straw. Under high pressure at the die head, the crushed plant material is forced into a high-pressure retainer system for high-temperature and high-pressure cooking, followed by explosion, and then the material is sent to the subsequent enzymatic hydrolysis tank for enzymatic fermentation to produce usable resources such as sugar alcohols and ethanol.

[0003] Document CN102371204A discloses a method for crushing and puffing plant fiber raw materials. The plant fiber raw materials are continuously conveyed, extruded, crushed, kneaded and puffed in a crushing and puffing machine. The machine includes a motor, coupling, reducer, feeding hopper, conical cylinder, straight cylinder and template. A water-permeable screen is set below the feeding hopper and the conical cylinder. Shear screws are set on the inner wall of the conical cylinder and the straight cylinder.

[0004] Current screw extruders generally employ screws with constant or variable outer diameters, using a conical feed plug outlet to address the issue of steam backflow within the connected retainer. However, practical experience shows that interrupted or discontinuous feeding, or insufficient feed rate, can lead to a leaky feed plug, causing steam backflow and posing a hazard. Furthermore, existing screw extruders lack effective devices for measuring material pressure at the die head, making it impossible to obtain data on the relationship between the maximum pressure of the feed plug seal and the feed rate. To ensure the safe and reliable operation of screw extruders and improve the efficiency of ethanol production from plant fibers, a safer and more reliable method to prevent steam backflow is essential. Summary of the Invention

[0005] The technical problem this invention aims to solve is the steam backflow issue caused by unstable feed conditions in existing screw mill technology, as well as problems such as easy clogging of the screw pulverizer filter, inability to monitor the head pressure, slow backflow response, and poor flowability of solid materials. This invention provides a device for monitoring the head pressure of a plant fiber pulverizer and preventing backflow. This device features fast steam backflow response, simple structure, and the ability to process plant fiber raw materials of different specifications and with unstable feed conditions. It can monitor head pressure data in real time, obtaining the relationship between feed rate, motor speed, and head pressure, providing data support for exploring plant cellulose pretreatment under different working conditions.

[0006] According to one aspect of this utility model, a pressurized continuous feeding dewatering device for straw steam explosion pretreatment is provided, comprising a variable diameter screw, a double-layer feeding hopper, a conical section cylinder, a straight section cylinder, a head pressure measuring device, a head, a retainer cylinder, and an anti-backflow device; wherein, the double-layer feeding hopper, the conical section cylinder, and the straight section cylinder are connected in sequence, and the straw material forms a stable material plug in the gap between the straight section cylinder and the variable diameter screw due to the compression action; the head pressure measuring device is located at the end of the straight section cylinder away from the conical section cylinder; the head and the anti-backflow device are respectively located on both sides of the retainer cylinder. The spraying device includes an emergency blocking valve and an anti-backflow cylinder. Under normal operating conditions with stable material supply, the variable diameter screw operates normally, the backflow structure below the double-layer feed hopper is periodically opened, the pressure value of the die head monitored by the die head pressure measuring device is stable, and the straw material is continuously conveyed in the conical section and the straight section of the cylinder, squeezed and dehydrated, kneaded and refined, and then sent into the retention tank cylinder for reaction. When the material supply is unstable, the pressure value of the die head monitored by the die head pressure measuring device suddenly decreases, which is fed back to the anti-backflow cylinder. The anti-backflow cylinder drives the emergency blocking valve to block the die head outlet and prevent steam backflow.

[0007] According to another aspect of the present invention, a pressurized continuous feeding dewatering method for straw steam explosion pretreatment is provided, which is applied to the above-mentioned pressurized continuous feeding dewatering device for straw steam explosion pretreatment. The method includes: when the pressure at the die head is detected to be less than 1.2 times the pressure of the inner cylinder of the retainer, stopping the variable diameter screw motor, and driving the emergency blocking valve through the anti-backflow cylinder to block the discharge port of the die head to prevent steam backflow. Attached Figure Description

[0008] The present patent will be further described below with reference to the accompanying drawings and specific embodiments.

[0009] Figure 1 This is a schematic diagram of the pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment in this utility model.

[0010] Figure 2 This is a schematic diagram of the feeding hopper in this utility model.

[0011] Figure 3 This is a schematic diagram showing the distribution of slots in the conical and straight sections of the cylinder in this utility model.

[0012] Figure 4 This is a schematic diagram of the head pressure measuring device in this utility model.

[0013] Figure 5 This is an enlarged schematic diagram of the machine head in this utility model.

[0014] Figures 1-5In the diagram, 1 is the motor, 2 is the protective cover, 3 is the coupling, 4 is the lower support base plate, 5 is the reducer, 6 is the reducing screw, 7 is the double-layer feed hopper, 7-1 is the inspection port and cleaning port, 7-2 is the inner hopper, 7-3 is the outer hopper, 7-4 is the gas backflush port, 8 is the conical section cylinder, 9 is the straight section cylinder, 9-1 is the shearing screw, 10 is the machine head pressure measuring device, 10-1 is the measuring head, 10-2 is the rubber O-ring, 10-3 is the connecting cap, 10-4 is the copper gasket ①, 10-5 is the transition cavity, 10-6 is the copper gasket ②, 10-7 is the pressure sensor connector, 11 is the straight section connecting flange, 12 is the machine head, 13 is the retainer cylinder, 14 is the anti-backflow device, 14-1 is the emergency material blocking valve, and 14-2 is the anti-backflow cylinder. Detailed Implementation

[0015] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0016] like Figure 1 As shown, this utility model provides a pressurized continuous feeding dewatering device for straw steam explosion pretreatment, including a variable diameter screw 6, a double-layer feeding hopper 7, a conical section cylinder 8, a straight section cylinder 9, a head pressure measuring device 10, a head 12, a retainer cylinder 13, and an anti-backflow device 14; wherein, the double-layer feeding hopper 7, the conical section cylinder 8, and the straight section cylinder 9 are connected in sequence, and the straw material forms a stable material plug in the gap between the straight section cylinder 9 and the variable diameter screw 6 due to the compression action. The head pressure measuring device 10 is located at the end of the straight section cylinder 9 away from the conical section cylinder 8. The head 12 and the anti-backflow device 14 are respectively located on both sides of the retainer cylinder 13. It includes an emergency blocking valve 14-1 and an anti-backflow cylinder 14-2. Under normal working conditions with stable material supply, the variable diameter screw 6 operates normally, the backflow structure below the double-layer feed hopper 7 is periodically opened, the head pressure value monitored by the head pressure measuring device 10 is stable, and the straw material is continuously conveyed in the conical section and the straight section, squeezed and dehydrated, kneaded and refined, and then sent into the retention cylinder 13 for reaction. When the material supply is unstable, the head pressure value monitored by the head pressure measuring device 10 suddenly decreases, which is fed back to the anti-backflow cylinder 14-2. The anti-backflow cylinder 14-2 drives the emergency blocking valve 14-1 to block the head outlet and prevent steam backflow.

[0017] The screw crusher, along its running direction, includes, in sequence: motor 1, protective cover 2, coupling 3, lower support base plate 4, reducer 5, variable diameter screw 6, double-layer feed hopper 7, conical section cylinder 8, straight section cylinder 9, head pressure measuring device 10, straight section connecting flange 11, head 12, retainer cylinder 13, and anti-backflow device 14. The double-layer feed hopper 7 has a water-permeable screen around its inner layer. The conical section cylinder 8 has 3×4 shearing screws 8-1, 2, and 3; the straight section cylinder 9 has 4×4 shearing screws 9-1; the head pressure measuring device 10 is located at the end of the straight section cylinder 9; the straight section cylinder 9 and the straight section connecting flange 11 are connected by threads; the head 12 and the retainer cylinder 13 are connected by bolts; the anti-backflow device 14 and the retainer cylinder 13 are connected by bolts; simultaneously, the head pressure measuring device 10 and the anti-backflow device 14 are connected to a PLC control system for data monitoring and status control.

[0018] In the above technical solution, the tail end face of the variable diameter screw 6 has an M24 threaded hole, and it is fixed to the rear end cover of the reducer by a long screw to ensure that the screw shaft does not move back and forth during the operation of the crusher cavity, so as to prevent the screw ribbon from colliding with the shearing screw; Figure 2 As shown, the double-layer feed hopper 7 adopts a U-shaped double-layer hopper structure. The U-shaped structure can improve the mixing degree of plant fiber raw materials and acid solution. Inspection and cleaning ports 7-1 are opened on the side of the outer hopper. The inner hopper 7-2 is filled with φ3-15mm filter holes to prevent excessive acid solution from causing material to float and preventing the screw from conveying material. A φ90-105mm filter liquid drainage collection port is opened at the lower end of the outer hopper 7-3. Simultaneously, a gas backflush port 7-4 is opened at the straight section at the lower end of the outer hopper. The backflush pipe is connected to compressed air, and 0.2-0.8MPa air is periodically blown out to clean the filter screen holes, preventing particulate matter in the material from clogging the inner hopper and causing liquid accumulation. Figure 3 As shown, 12 annular grooves are opened around the conical section 8 and the straight section 9 to ensure that the mixed acid solution can flow back to the filter hole of the inner hopper 7-2 through the annular grooves during the extrusion of plant fiber raw materials by the screw press, thus achieving the purpose of acid circulation.

[0019] like Figure 4As shown, in this scheme, the die head pressure measuring device 10 consists of a measuring head 10-1, a rubber O-ring 10-2, a connecting cap 10-3, a copper gasket ① 10-4, a transition cavity 10-5, a copper gasket ② 10-6, and a pressure sensor connector 10-7. The transition cavity 10-5 is connected to the straight pipe section cylinder through an external thread. The measuring head 10-1 and the connecting cap 10-3 are located on both sides of the transition cavity boss and are fixed by threads. The transition cavity 10-5 is filled with high-pressure industrial oil. In actual operation, the measuring head 10-1 monitors the material pressure at the die head of the screw compressor and feeds it back to the pressure sensor connector through the high-pressure oil in the transition cavity. The pressure sensor transmits the data to the PLC control system, thereby monitoring the die head pressure data of the screw compressor in real time. Since straw material is a mixture of solid material and acid solution, traditional pressure sensors may experience data deviation or even damage due to material adhesion. However, the pressure measurement device at the machine head of this solution separates the pressure sensor connector from the straw material, which not only effectively avoids errors caused by material adhesion, but also isolates the high-temperature material from the sensor with industrial oil, ensuring that the sensor's sensitivity is not affected by the high temperature generated by friction between the material and the cavity.

[0020] In this design, the straight section connecting flange 11 is connected to the straight section cylinder 9 via a standard M3 coarse thread, ensuring that the bolt connection holes between the flange and the retainer cylinder 13 are aligned to prevent excessive hard connection stress caused by machining errors at both ends of the straight section cylinder. The die head 12 is inserted into the retainer cylinder 13 and fixed to the cylinder with screws. The ratio of the length X1 of the straight section cylinder 9 to the length X2 of the conical section cylinder 8 is 4:3 to 5:3, with the longer straight section cylinder forming a stable feed plug with the screw. Figure 5 As shown, the opening angle θ1 between the cone section of the die head and the center line is 5-8° smaller than the angle θ2 between the cone section of the screw shaft and the center line, so as to form a diffusion discharge channel and increase the expansion effect of plant fiber materials; the anti-backflow device 14 consists of an emergency blocking valve 14-1 and an external thread anti-backflow cylinder 14-2. When the cylinder is activated, the piston rod drives the emergency blocking valve to press into the die head 12 to prevent the high-pressure steam in the inner cylinder of the retainer from backflowing.

[0021] In this design, motor 1 is equipped with a frequency converter; reducer 5 is a two-stage helical gear reducer with a thrust bearing housing; the screw shaft with equal root diameter and the crusher cavity are made of S31603 stainless steel; the shear screw is made of A2-70 material; and the rubber O-ring is made of high-temperature and acid-resistant fluororubber. During normal operation, the preferred temperature range for the crusher is 100–250℃, the pressure range is 0.5–1.5MPa, the preferred screw speed range is 15–60 rpm, and the preferred stable feed rate range is 200–1000 kg / hour. When the feed rate is below 50 kg / hour and the pressure in the retainer is above 1.5MPa, the head pressure sensor detects a head pressure below 1.8MPa, which stops the screw motor and simultaneously controls the anti-backflow cylinder feed to prevent steam backflow.

[0022] In this scheme, plant fiber raw materials and acid are added from the double-layer feed hopper 7. The reducer 5 drives the variable diameter screw 6 to rotate, causing the mixture to move forward. Under the combined action of the variable diameter screw and the shear screw, the material is squeezed, dehydrated, kneaded, and crushed in the crusher cavity. Most of the water in the plant fiber mixed with the soaking acid flows back to the bottom filter screen of the double-layer feed hopper 7 through the cavity groove to complete the acid circulation. A small portion of the water vaporizes due to the friction between the plant fiber material and the cavity, and is ejected into the subsequent retention device as the material expands at the gap of the die head 12. When the material is uneven or the amount of material is too small, the die head pressure sensor detects fluctuations in the die head pressure. When the die head pressure is less than 1.2 times the pressure of the retention device inner cylinder, the program stops the screw motor and simultaneously controls the feed of the anti-backflow cylinder, and the emergency blocking valve seals the die head outlet to prevent steam backflow and material backflow from the retention device inner cylinder, thus preventing damage.

[0023] In this solution, the screw crusher uses back-blowing air below the feed hopper to clean the filter screen, grooves inside the chamber to facilitate acid reflux, a special head pressure measuring device to monitor head pressure data, a diffusion-type discharge channel between the head and screw to achieve better puffing effect, and an anti-backflow cylinder actuator to prevent steam backflow. Therefore, compared with traditional screw crushers, this method not only has a simple structure, smooth acid filtration and circulation, good material puffing effect, real-time monitoring of head pressure data, and fast steam backflow response, but also can process plant fiber raw materials of different specifications and unstable incoming conditions.

[0024]

Example 1

[0025] use Figure 1The screw extruder system shown in the diagram feeds corn stalks and plant fiber material, crushed to 20-30mm, mixed with a 3% dilute sulfuric acid solution, into the double-layer feed hopper 7. The motor frequency is controlled at 30Hz, and the motor reducer drives the variable-diameter screw 6 to rotate at 35 rpm. The straw-acid mixture moves forward under the screw's thrust. Due to the presence of the shear screw, the material does not become stuck to the shaft. The material is squeezed, dehydrated, kneaded, and crushed within the chamber. Most of the water flows back through the chamber's grooves to the lower filter screen of the feed hopper for acid circulation. With the backflushing air at 0.5MPa activated periodically, the filter screen remains unclogged. A small portion of the water vaporizes due to friction and is continuously and stably sprayed out from the die head along with the corn stalk material. The sprayed material exhibits good crushing and puffing effects and good flowability. Simultaneously, the real-time data from the die head sensor is stable, ensuring smooth system operation.

[0026]

Example 2

[0027] Similar to Example 1, when feeding material into the double-layer feeding hopper 7 suddenly stops, the motor runs normally and the shaft rotates normally. When the variable diameter screw 6 continues to push the remaining material forward, the sensor data of the die head is stable and the die head sprays material normally. After running for a period of time, the pressure data of the die head suddenly decreases, the motor stops rotating, the anti-backflow cylinder quickly executes the action, and the piston rod drives the emergency blocking valve to seal the discharge port of the die head. There is no backflow of steam and the response is rapid.

[0028]

Example 3

[0029] Similar to Example 1, the straw raw material is fed discontinuously into the double-layer feeding hopper 7 under manual control. At this time, the data of the machine head sensor fluctuates. When the real-time pressure measured by the machine head sensor is less than 1.2 times the pressure of the inner cylinder of the retainer at a certain moment, the motor stops rotating, the anti-backflow cylinder quickly executes the action, and the piston rod drives the emergency blocking valve to seal the machine head outlet. There is no backflow of steam, and the response is rapid.

Claims

1. A pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment, characterized in that, The device includes a variable-diameter screw (6), a double-layer feed hopper (7), a conical section cylinder (8), a straight section cylinder (9), a head pressure measuring device (10), a head (12), a retainer cylinder (13), and an anti-backflow device (14). The double-layer feed hopper (7), conical section cylinder (8), and straight section cylinder (9) are connected sequentially. Due to compression, the straw material forms a stable plug in the gap between the straight section cylinder (9) and the variable-diameter screw (6). The head pressure measuring device (10) is located at the end of the straight section cylinder (9) away from the conical section cylinder (8). The head (12) and the anti-backflow device (14) are located on opposite sides of the retainer cylinder (13). The anti-backflow device (14) includes an emergency plugging mechanism. Valve (14-1) and anti-backflow cylinder (14-2); Under the normal working condition of stable incoming material, the variable diameter screw (6) operates normally, the backflow structure below the double-layer feed hopper (7) is opened periodically, the pressure value of the head monitored by the head pressure measuring device (10) is stable, the straw material is continuously conveyed in the conical section cylinder and the straight section cylinder, squeezed and dehydrated, kneaded, refined and crushed and then sent into the retention cylinder (13) for reaction; when the incoming material is unstable, the pressure value of the head monitored by the head pressure measuring device (10) suddenly decreases and is fed back to the anti-backflow cylinder (14-2), the anti-backflow cylinder (14-2) drives the emergency blocking valve (14-1) to block the head outlet and prevent steam backflow.

2. The pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment according to claim 1, characterized in that, The double-layer feeding hopper (7) adopts a U-shaped double-layer hopper structure. The inner hopper has a filter screen with a diameter of φ3-15mm, and the outer hopper has a filter liquid drainage collection port with a diameter of φ90-105mm at the bottom. At the same time, the filter liquid drainage collection pipe at the bottom is equipped with an upward back-blowing air structure, which periodically back-blowing 0.2~0.8MPa of air to prevent the inner filter screen from clogging.

3. The pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment according to claim 1, characterized in that, The head pressure measuring device (10) includes a measuring head, a connecting cap, a transition cavity, and a pressure sensor connector; the transition cavity is connected to the straight section cylinder (9), the measuring head and the connecting cap are respectively set on both sides of the boss of the transition cavity, and the transition cavity is filled with industrial oil; the measuring head monitors the material pressure at the head and feeds back to the pressure sensor connector through the industrial oil in the transition cavity, and the pressure sensor connector is isolated from the straw material by industrial oil.

4. The pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment according to claim 1, characterized in that, The ratio of the length of the straight section cylinder (9) to the length of the conical section cylinder (8) is: X1:X2=4:3~5:

3. This ensures that the pressure at the head of the machine is higher than the pressure inside the retainer under stable material conditions, thus preventing steam backflow.

5. The pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment according to claim 1, characterized in that, The included angle θ1 of the die head opening is 5-8° smaller than the cone angle θ2 of the variable diameter screw shaft head, so as to form a diffusion-type discharge channel.

6. The pressurized continuous feeding dewatering device for straw steaming and explosion pretreatment according to claim 1, characterized in that, The emergency blockage valve (14-1) is tightly fitted to the tail of the head (12) to prevent steam backflow and leakage.

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