PVA alcoholysis system

Abstract

The invention provides a PVA alcoholysis system. The device comprises a plurality of columns of alcoholysis machines arranged side by side at intervals, a charging assembly arranged above the alcoholysis machines and used for forming a striker plate, a feeding assembly used for conveying reactants to an alcoholysis machine belt, a temperature measuring assembly used for detecting the temperature of the reactants in the alcoholysis machines, a flushing assembly used for flushing the alcoholysis machine belt and a controller, the temperature measuring assembly is arranged above a belt of the alcoholysis machine, the flushing assembly is arranged below the belt of the alcoholysis machine, and the alcoholysis machine, the charging assembly, the feeding assembly, the temperature measuring assembly and the flushing assembly are all connected with the controller. According to the PVA alcoholysis system, reactants do not make contact with operators, material leakage is avoided, the service life of the belt is prolonged, temperature is accurately measured, and the product quality is improved.

Description

Technical Field

[0001] The present invention belongs to the field of polyvinyl alcohol production, and particularly relates to a PVA alcoholysis system. Background Art

[0002] Polyvinyl alcohol (PVA) is an important water-soluble synthetic polymer, which is widely used in many fields. Polyvinyl alcohol is obtained by the transesterification reaction of polyvinyl acetate and methanol at a certain temperature with sodium hydroxide as a catalyst, and side reactions also occur simultaneously. The reaction equations are as follows: 1. Transesterification reaction (alcoholysis reaction): ; 2. Saponification reaction: ; 3. Side reaction: .

[0003] The alcoholysis machine provides a reaction site for the above reactions. The alcoholysis machine includes a housing, a belt, and a variable frequency speed regulation mechanism. The housing is of a jacketed design, and warm water flows in the jacket. The reaction is an exothermic reaction, and the function of the jacket is to adjust the temperature inside the alcoholysis machine to always be the temperature required for the reaction. The belt is arranged inside the housing, and the belt has a concave surface, which is used to carry the reactants. The reactants react at the concave surface of the belt to produce polyvinyl alcohol. The belt is made of polypropylene or rubber. The variable frequency speed regulation mechanism is used to adjust the rotation speed of the belt, control the reaction time, and produce PVA with different degrees of alcoholysis.

[0004] After the polyvinyl acetate methanol solution and the alkali methanol solution enter the alcoholysis machine, they react as the belt moves forward. Finally, blocky polyvinyl alcohol is formed at the end of the belt and is transported to a crusher through the material outlet of the alcoholysis machine for crushing. Then, it is dehydrated by a dehydrator and dried by a dryer to obtain the finished PVA, which is used by downstream users in the production of PVB (polyvinyl butyral), water-soluble fibers, various glues, etc. The tail gas (mainly methanol and methyl acetate) generated by the reaction and the waste liquid (mainly methanol and methyl acetate) generated by the reaction are transported to a recovery process for separation, hydrolysis, rectification, and purification to obtain recovered methanol and recovered acetic acid for production and recycling.

[0005] Defects existing in the prior art: 1. The feeding operation is cumbersome and there are safety risks: Because the polyvinyl acetate methanol solution and alkali solution are in a liquid flow state when they first enter the alcoholysis machine, the alcoholysis machine baffle plate is needed to block the liquid for the first feeding so that it reacts to form blocky PVA, which is convenient for entering the crushing device. Because the alcoholysis machine baffle plate currently used is a combination of an iron baffle plate and an iron block, firstly, it is easy to scratch the alcoholysis machine belt (made of smooth polypropylene or rubber material) during use, which not only shortens the use cycle of the alcoholysis machine, but also makes it easier for the material to stick after being scratched; secondly, it is inconvenient to operate, and the iron baffle plate and iron block need to be manually placed at the head of the alcoholysis machine before feeding, and then manually removed from the tail of the alcoholysis machine after the material is reacted and formed, but because the baffle plate and iron block are heavy, and there is PVA adhesion, it is difficult to remove them. If they cannot be removed in time, it will cause parking. If the baffle plate accidentally enters the crusher and collides with the crusher blade, a major safety accident will occur; thirdly, due to the high methanol content in the alcoholysis machine, if the baffle plate is improperly operated during the process of removing the baffle plate, fire and explosion accidents are likely to occur (similar accidents have occurred in the same industry); fourthly, the two sides of the alcoholysis machine inlet are smooth curved surfaces. If the sealing is not strict, leakage is likely to occur. After the leakage, the PVA formed is too thin to enter the crusher for crushing, causing parking; 2. The alcoholysis machine belt has a short service life: There are two materials for alcoholysis machine belts currently used in the industry, one is polypropylene and the other is rubber. No matter which material is used, the material will stick to the belt. The material stuck to the belt will undergo a significant change in internal quality due to long-term overreaction, and will eventually be brought into the product (called white spot material in the industry). The material stuck to the belt not only affects the product quality, but also causes tension and damage to the belt when it falls off. If it is not discovered or the belt is not replaced in time, it will cause leakage and equipment damage accidents. If it is not handled properly, it may even cause fire and explosion accidents. 3. It is well known that reaction temperature is one of the important factors of chemical reactions. The accuracy and stability of temperature directly affect the degree of reaction and the final result. Alcoholysis reaction is an exothermic reaction. At present, there are two aspects to control the reaction temperature in the industry. One is to control the feed temperature (the temperature of polyvinyl acetate methanol solution and alkali methanol solution before contact and mixing), and the other is to control the temperature of the alcoholysis machine. The feed temperature can be basically stable because of the heat exchanger and pipeline insulation facilities, but once the two raw materials (polyvinyl acetate methanol solution and alkali methanol solution) come into contact, they will start to react and release heat, and the reaction temperature will change according to the changes in raw material concentration and flow rate. At present, the industry's method of measuring the temperature of the alcoholysis machine is to detect the space temperature above the belt alcoholysis machine box, but this detection cannot accurately measure the material temperature on the belt, so it is impossible to adjust the process (feed temperature, alkali ratio, etc.) in time, resulting in a wide distribution of alcoholysis degree and unstable quality of the final product. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a PVA alcoholysis system, in which the reactants do not come into contact with the operators, avoiding material leakage, prolonging the service life of the belt, accurately measuring the temperature, and improving the product quality.

[0007] The technical solution adopted by the present invention is as follows: A PVA alcoholysis system includes multiple rows of alcoholysis machines arranged side by side at intervals, a feeding component arranged above the alcoholysis machines and used for forming a baffle plate, a feeding component used for conveying reactants to the belt of the alcoholysis machine, a temperature measuring component used for detecting the temperature of the reactants inside the alcoholysis machine, a washing component used for washing the belt of the alcoholysis machine, and a controller. The temperature measuring component is arranged above the belt of the alcoholysis machine, and the washing component is arranged below the belt of the alcoholysis machine. The alcoholysis machine, the feeding component, the feeding component, the temperature measuring component, and the washing component are all connected to the controller.

[0008] Further, the alcoholysis machine can be, for example, 2 - 10 rows, preferably 5 - 8 rows. The multiple rows of alcoholysis machines are, for example, arranged at equal intervals. The alcoholysis machines are arranged in the production workshop, and each row of alcoholysis machines is controlled independently. The alcoholysis machine includes a box body provided with a jacket, a belt arranged inside the box body, a driving roller connected to one end of the belt and driving the belt to rotate, and a driven roller connected to the other end of the belt. The jacket is communicated with a warm water tank through a warm water conveying pipe. The warm water tank uses steam, process water, and dryer condensate to adjust the addition amount through a regulating valve for temperature control. A warm water valve is provided on the warm water conveying pipe, and both the warm water valve and the warm water tank are connected to the controller. There are multiple convex protrusions distributed along the length direction of the alcoholysis machine on the top plate of the box body. The convex protrusions can be, for example, 3 - 10, preferably 5 - 8. The convex protrusions are of a jacketed cuboid structure. The length of the convex protrusions can be, for example, 2.5 - 3 m, the width can be, for example, 5 - 15 cm, and the height can be, for example, 20 - 50 cm. The space surrounded by the convex protrusions is communicated with the space inside the alcoholysis machine. The jacket of the convex protrusions is communicated with the jacket of the box body. The convex protrusions include multiple side walls and a top wall connected to the top of the side walls. A wire outlet hole is opened on the top wall. A hand hole for injecting PVA material onto the belt is opened at the end of the top plate of the box body. An inlet port is opened on the top plate at a distance from the hand hole. The inlet port is closer to the driving roller than the hand hole. The belt is provided with a concave surface for accommodating the reactants. The discharge port at the end of the alcoholysis machine is connected to a pulverizer.

[0009] Further, the feeding assembly includes a slide rail fixed to the workshop roof and spanning all alcoholysis machines, an electric hoist slidably connected to the slide rail, a feeding hopper connected below the electric hoist, a feeding pipe connected to the discharge port of the feeding hopper and hanging down, and a feeding valve provided on the feeding pipe. The length direction of the slide rail is perpendicular to the length direction of the alcoholysis machine. Right below the slide rail, at the position opposite to the manhole of the alcoholysis machine, both the electric hoist and the feeding valve are connected to the information output end of the controller. The feeding hopper is filled with PVA particles or PVA sheets or a mixture of PVA particles and PVA sheets. The model of the PVA particles or sheets is the same as the polyvinyl alcohol model to be produced on the alcoholysis machine. The feeding pipe moves directly above the straight line where the manhole is located, adding the PVA particles or sheets in the feeding hopper to the belt. The controller controls the moving position of the electric hoist on the slide rail and the opening and closing of the feeding valve.

[0010] Further, the feeding component includes a feeding pipe extending from the feeding port into the alcoholysis machine above the concave surface of the belt and a first control valve provided on the feeding pipe. The first control valve is connected to the information output end of the controller. Preferably, the first control valve is provided on the feeding pipe outside the alcoholysis machine. Preferably, the feeding pipe includes a polyvinyl acetate methanol solution conveying pipe and a sodium hydroxide methanol solution conveying pipe arranged in parallel. First control valves are provided on both the polyvinyl acetate methanol solution conveying pipe and the sodium hydroxide methanol solution conveying pipe.

[0011] Further, the temperature measuring assembly includes an inclined track provided in the convex hull, limiters provided at both ends of the track, a trolley sliding along the track, a cylinder fixed to the trolley, a thermal resistance core rod connected below the cylinder, a power supply line extending from the wire outlet hole and connected to the thermal resistance core rod, a gas supply line connected to the cylinder, a solenoid valve provided on the gas supply line, and a winding for winding the gas supply line and the power supply line. Each thermal resistance core rod is controlled separately.

[0012] Further, a track is provided in each convex hull. The track gradually rises along the advancing direction of the reactants. The track includes two single tracks arranged in parallel at intervals. Each single track is of a groove type. The limiters are touch sensors. There are two limiters, namely a high - level limiter and a low - level limiter. The high - level limiter is connected to the rising end of the track, and the low - level limiter is connected to the other end of the track. The two limiters are respectively fixed on two parallel side walls of the convex hull. The limiters are connected to the information input end of the controller.

[0013] Further, the trolley includes wheels, an axle connected to the wheels, and a frame plate provided on the axle. The wheels roll on the single track. For example, there can be four wheels. Every two wheels form a group. The wheels in the same group are connected to both ends of the axle. The axle is used to support the frame plate. Through holes for fixing the cylinder are opened on the frame plate. The trolley slides down along the track from high to low under the action of its own gravity.

[0014] Furthermore, the cylinder includes a cylinder barrel and a telescopic rod that slides along the cylinder barrel. One end of the air source line is connected to the cylinder barrel for inputting or outputting gas into or from the cylinder barrel. When gas is input, the telescopic rod is pushed out of the cylinder barrel, and when gas is output, the telescopic rod retracts. The telescopic direction of the telescopic rod is perpendicular to the belt. The thermal resistance core rod is fixed to the free end of the telescopic rod. The thermal resistance core rod has a remote transmission function, and the central axis of the thermal resistance core rod is consistent with the central axis of the telescopic rod. The end of the thermal resistance core rod is pointed, so that when the free end of the telescopic rod moves towards the belt, it can drive the thermal resistance core rod to move downward synchronously and make its pointed end easier to insert into the reactant on the belt. The length of the thermal resistance core rod can be, for example, 10 - 20 cm, and the length inserted into the reactant can be, for example, 3 - 8 cm. Fins are provided at the lower part of the thermal resistance core rod. There can be, for example, two fins, and the two fins are symmetrically arranged on both sides of the thermal resistance core rod. The fins can be in the shape of, for example, a triangle or a square, etc. The bottom edge of the fin forms a cutting edge, making it easier for the fin to insert into the reactant. The plane where the fin is located is perpendicular to the advancing direction of the reactant. The function of the fin is to enable the pointed end of the thermal resistance core rod to be firmly inserted into the reactant and hold the reactant in a stable state, so that the reactant can push the thermal resistance core rod, the trolley, and the cylinder to move obliquely upward along the track. The other end of the air source line is connected to the gas storage cylinder through an air source switch. Both the air source switch and the solenoid valve are connected to the controller. The solenoid valve is, for example, a two-position five-way solenoid valve. The air source can be, for example, nitrogen. The principle of the solenoid valve and the air source switch controlling the expansion and contraction of the cylinder is a commonly used technology in the field and will not be elaborated here. The air source line and the power line are in a multi-turn spiral winding state between the winding and the cylinder, enabling the cylinder and the thermal resistance core rod to move freely along the track. In the initial state, the trolley is located at the lowest point of the track and contacts the low-position limiter. The controller controls the solenoid valve and the air source switch, and gas enters the cylinder barrel, pushing out the telescopic rod. The telescopic rod drives the bottom end and the fins of the thermal resistance core rod to insert into the reactant, measures the reaction temperature of the reactant, and sends the temperature information to the controller. The controller controls the heating power of the warm water tank and the opening degree of the warm water valve through the monitored reactant temperature in a chain manner, thereby adjusting the temperature of the warm water entering the box jacket. The operator timely adjusts the process, such as the alkali ratio, feed temperature, etc., according to the monitored reactant temperature. The reactant pushes the thermal resistance core rod, the cylinder, and the trolley to move obliquely upward along the track. When the trolley touches the high-position limiter, the high-position limiter sends information to the controller. The controller controls the solenoid valve and the air source switch, and gas is discharged from the cylinder barrel, and the telescopic rod retracts. The thermal resistance core rod rises above the reactant. The trolley moves to the initial position under its own gravity and contacts the low-position limiter. The controller records the time when the trolley touches the low-position limiter. After reaching the set interval time (which can be, for example, 5 - 15 minutes), the controller controls the solenoid valve and the air source switch again, and gas enters the cylinder barrel for circulation, and the temperature of the reactant is measured for the second time.

[0015] Furthermore, the flushing assembly includes a plurality of nozzles arranged below the belt, a liquid inlet pipe for conveying flushing liquid, a liquid collecting cover arranged around the nozzles and for collecting flushing liquid, and a liquid outlet pipe connected to the bottom end of the liquid collecting cover.

[0016] Furthermore, multiple nozzles are arranged side by side at equal intervals, and the distance between adjacent nozzles ensures uniform flow distribution. The number of nozzles can be, for example, 3-5. The nozzles are preferably fan-shaped nozzles to increase the spraying range. A flat nozzle is opened on the top of the nozzle, and the long axis of the nozzle is perpendicular to the direction of advance of the belt. The nozzle faces the back of the belt. The nozzle is preferably aligned with the concave surface of the belt. The front of the belt is used to place the reactants. After the belt is redirected by the driven roller, the front becomes the back facing downward. One end of the liquid inlet pipe extends into the liquid collecting hood and is connected to the liquid spray main pipe. The liquid spray main pipe is divided into multiple branch pipes extending upward. The port of each branch pipe is connected to a nozzle. The liquid inlet pipe is away from One end of the nozzle is connected to a waste liquid collecting tank, in which alcoholysis waste liquid or methanol solution is stored. The alcoholysis waste liquid (main components are 70% methanol and 28% methyl acetate) or methanol solution is used as a flushing liquid to flush the material adhering to the belt. A liquid pump, a regulating valve and a flow meter are sequentially arranged on the liquid inlet pipe along the conveying direction of the flushing liquid. The liquid pump and the regulating valve are both connected to the information output end of the controller, and the flow meter is connected to the information input end of the controller. Preferably, the liquid inlet pipe is divided into a plurality of branch pipes after entering the box body, and the plurality of branch pipes extend to the front end, the middle and the rear end of the belt respectively, and the branch pipes enter the liquid collecting hood and are connected to the liquid spraying main pipe.

[0017] Furthermore, the liquid collecting hood is an inverted cone that is larger at the top and smaller at the bottom. The top edge of the liquid collecting hood surrounds the nozzle and fits the belt. The top opening of the liquid collecting hood can be, for example, a rectangle. The length of the top opening of the liquid collecting hood can be, for example, consistent with the width of the belt. The bottom end of the liquid collecting hood forms a closed end and is connected to one end of the liquid outlet pipe. A through hole is opened on the liquid collecting hood, and the through hole is used for the liquid inlet pipe to enter the interior of the liquid collecting hood. The flushing liquid in the waste liquid collecting tank is pressurized by a liquid pump and transported to the nozzle to flush the front, middle and rear ends of the belt respectively, and the material adhering to the belt is flushed. The flushing liquid and reaction waste liquid are collected by the liquid collecting hood and enter the liquid outlet pipe. The flow meter monitors the flushing liquid flow in the liquid inlet pipe and interlocks the control valve. The material of the liquid collecting hood can be, for example, thermoplastic plastics such as polypropylene.

[0018] Furthermore, the liquid outlet pipe is divided into two branches after passing through the filter, one of which is connected to the waste liquid collecting tank, and the flushing liquid and reaction waste liquid are transported to the waste liquid collecting tank for secondary utilization; the other branch is connected to the recovery process, which is used to recycle the flushing liquid and reaction waste liquid. The liquid outlet pipe can be, for example, a hard pipe for supporting the liquid collecting hood.

[0019] Further, the controller is a programmable logic controller.

[0020] Beneficial effects of the present invention: A PVA alcoholysis system provided by the present invention, by setting an electric hoist, a slide rail, a feeding hopper, a discharging pipe and a discharging valve, the controller controls the feeding hopper to move back and forth above the concave surface of the belt of the alcoholysis machine in a chained manner. The PVA material is piled up into a baffle. When the reactants reach the end of the belt, the massive PVA has been formed and integrated with the baffle. The baffle directly enters the crusher from the discharge port at the tail end of the alcoholysis machine along with the massive PVA without being taken out, ensuring safety. The baffle prevents the belt from leaking materials, does not scratch the belt, and prolongs the service life of the belt, safely and effectively completing the feeding process; by setting tracks, a trolley, a cylinder and a thermal resistance core rod in the convex bulge, the cylinder controls the thermal resistance core rod to insert into or pull out from the reactants, measuring the temperature of the reactants in multiple cycles. The thermal resistance core rod directly inserts into the reactants, accurately measuring the temperature change of the materials in the alcoholysis machine, improving the measurement accuracy, and timely adjusting the temperature of the warm water in the jacket and the process parameters to ensure the stability of the alcoholysis reaction; by setting a nozzle, a liquid inlet pipe, a liquid collecting hood and a liquid outlet pipe, the materials adhered to the belt are washed in time, avoiding the corrosion of the reactants to the belt and prolonging the service life of the belt; a PVA alcoholysis system provided by the present invention prolongs the service cycle of the belt of the alcoholysis machine, realizes automation from the feeding operation to the washing operation, not only reduces the labor intensity of the personnel, but also improves the safety factor, ensures the stability of the alcoholysis reaction, improves the product quality, and eliminates the potential safety hazards in production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the front view of a PVA alcoholysis system of the present invention.

[0022] Figure 2 It is the side view of a PVA alcoholysis system of the present invention.

[0023] Figure 3 It is the connection schematic diagram of the liquid collecting hood with the nozzle and the liquid inlet pipe Figure 1 .

[0024] Figure 4 It is the connection schematic diagram of the liquid collecting hood with the nozzle and the liquid inlet pipe Figure 2 .

[0025] Figure 5 It is the schematic diagram of the nozzle.

[0026] Figure 6 It is the schematic diagram of the process of the thermal resistance core rod moving along with the reactants on the belt.

[0027] Figure 7 It is the internal structure schematic diagram of the convex bulge.

[0028] Figure 8 It is for Figure 7 the front view of

[0029] Figure 9 It is the schematic diagram of the connection of the trolley with the cylinder.

[0030] Figure 10 is Figure 9 the enlarged view of location A in

[0031] Figure 11 is the schematic structural view of the track.

[0032] Figure 12 is the control block diagram of a PVA alcoholysis system of the present invention.

[0033] Reference numerals: 1 - alcoholysis machine, 101 - belt, 102 - box body, 103 - driving roller, 104 - driven roller, 105 - convex bulge, 106 - wire outlet hole, 107 - manhole, 2 - feeding assembly, 201 - slide rail, 202 - electric hoist, 203 - feeding hopper, 204 - blanking pipe, 205 - blanking valve, 301 - first control valve, 4 - temperature measuring assembly, 401 - track, 4011 - single track, 402 - limiter, 4021 - upper limiter, 4022 - lower limiter, 403 - trolley, 4031 - wheel, 4032 - axle, 4033 - frame plate, 404 - cylinder, 4041 - cylinder barrel, 4042 - telescopic rod, 405 - thermal resistance core rod, 4051 - fin, 4052 - cutting edge, 406 - solenoid valve, 407 - winding, 408 - air source switch, 5 - flushing assembly, 501 - spray head, 502 - liquid inlet pipe, 503 - liquid collecting hood, 504 - liquid pump, 505 - regulating valve, 506 - flowmeter, 507 - necking, 508 - spray orifice, 509 - liquid spraying main pipe, 6 - controller, 7 - production workshop, 8 - warm water tank, 9 - warm water valve, 10 - crusher. Detailed implementation manners

[0034] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0035] As Figure 1-12 shown, a PVA alcoholysis system includes multiple rows of alcoholysis machines 1 arranged side by side at intervals, a feeding assembly 2 arranged above the alcoholysis machines 1 and used for forming a baffle, a feeding assembly for conveying reactants to the belt 101 of the alcoholysis machines 1, a temperature measuring assembly 4 for detecting the temperature of the reactants inside the alcoholysis machines 1, a flushing assembly 5 for flushing the belt 101 of the alcoholysis machines 1, and a controller 6. The temperature measuring assembly 4 is arranged above the belt 101 of the alcoholysis machines 1, the flushing assembly 5 is arranged below the belt 101 of the alcoholysis machines 1, and the alcoholysis machines 1, the feeding assembly 2, the feeding assembly, the temperature measuring assembly 4, and the flushing assembly 5 are all connected to the controller 6.

[0036] As Figure 1 ,Figure 2 As shown, the alcoholysis machine 1 can be, for example, 2 - 10 columns, preferably 5 - 8 columns. Multiple columns of alcoholysis machines 1 are arranged at equal intervals, for example. The alcoholysis machine 1 is arranged in the production workshop 7, and each column of the alcoholysis machine 1 is controlled independently. The alcoholysis machine 1 includes a box body 102 with a jacket, a belt 101 arranged in the box body 102, a driving roller 103 connected to one end of the belt 101 and driving the belt 101 to rotate, and a driven roller 104 connected to the other end of the belt 101. The jacket is connected to the warm water tank 8 through a warm water delivery pipe. The warm water tank 8 is temperature - controlled, for example, by using steam, process water, and dryer condensate to adjust the addition amount through a regulating valve. A warm water valve 9 is arranged on the warm water delivery pipe. Both the warm water valve 9 and the warm water tank 8 are connected to the controller 6. On the top plate of the box body 102, there are multiple convex protrusions 105 distributed along the length direction of the alcoholysis machine 1. The convex protrusions 105 can be, for example, 3 - 10, preferably 5 - 8. The convex protrusions 105 are jacketed cuboid structures. The length of the convex protrusions 105 can be, for example, 2.5 - 3 m, the width can be, for example, 5 - 15 cm, and the height can be, for example, 20 - 50 cm. The space surrounded by the convex protrusions 105 is connected to the space inside the alcoholysis machine 1. The jacket of the convex protrusions 105 communicates with the jacket of the box body 102. The convex protrusions 105 include multiple side walls and a top wall connected to the top of the side walls. An outlet hole 106 is opened on the top wall. On the end of the top plate of the box body 102, there is a manhole 107 for injecting PVA material onto the belt 101. An inlet port is opened on the top plate at a certain distance from the manhole 107. The inlet port is closer to the driving roller 103 than the manhole 107. The belt 101 has a concave surface for accommodating the reactants. The discharge port at the end of the alcoholysis machine 1 is connected to the crusher 10.

[0037] As Figure 1 、 Figure 2 shown, the feeding assembly 2 includes a slide rail 201 fixed on the workshop roof and spanning all the alcoholysis machines 1, an electric hoist 202 slidably connected to the slide rail 201, a feeding hopper 203 connected below the electric hoist 202, a feeding pipe 204 connected to the discharge port of the feeding hopper 203 and hanging down, and a feeding valve 205 arranged on the feeding pipe 204. The length direction of the slide rail 201 is perpendicular to the length direction of the alcoholysis machine 1. Right below the slide rail 201, at the position directly opposite the manhole 107 of the alcoholysis machine 1, both the electric hoist 202 and the feeding valve 205 are connected to the information output end of the controller 6. The feeding hopper 203 contains PVA particles or PVA sheets or a mixture of PVA particles and PVA sheets. The model of the PVA particles or sheets is the same as the polyvinyl alcohol model to be produced on the alcoholysis machine 1. The feeding pipe 204 moves directly above the straight line where the manhole 107 is located, and adds the PVA particles or sheets in the feeding hopper 203 to the concave surface of the belt 101. The controller 6 controls the moving position of the electric hoist 202 on the slide rail 201 and the opening and closing of the feeding valve 205.

[0038] ​The feeding assembly includes a feeding pipeline extending from the feeding port into the alcoholysis machine 1 above the concave surface of the belt 101 and a first control valve 301 provided on the feeding pipeline. The first control valve 301 is connected to the information output end of the controller 6. Preferably, the first control valve 301 is provided on the feeding pipeline outside the alcoholysis machine 1. Preferably, the feeding pipeline includes a polyvinyl acetate methanol solution conveying pipeline and an alkali methanol solution conveying pipeline arranged in parallel, and the first control valve 301 is provided on both the polyvinyl acetate methanol solution conveying pipeline and the alkali methanol solution conveying pipeline.

[0039] As Figure 1 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 As shown, the temperature measuring assembly 4 includes an inclined track 401 provided in the convex hull 105, limiters 402 provided at both ends of the track 401, a trolley 403 sliding along the track 401, a cylinder 404 fixed on the trolley 403, a thermal resistance core rod 405 connected below the cylinder 404, a power line extending from the wire outlet hole 106 and connected to the thermal resistance core rod 405, a gas supply line connected to the cylinder 404, a solenoid valve 406 provided on the gas supply line, and a winding 407 for winding the gas supply line and the power line. Each thermal resistance core rod 405 is controlled separately.

[0040] A track 401 is provided in each convex hull 105. The track 401 gradually rises along the advancing direction of the reactants. The track 401 includes two parallel and spaced single tracks 4011. Each single track 4011 is of a groove type. The limiter 402 is a touch sensor. There are two limiters 402, namely a high-level limiter 4021 and a low-level limiter 4022. The high-level limiter 4021 is connected to the rising end of the track 401, and the low-level limiter 4022 is connected to the other end of the track 401. The two limiters are respectively fixed on two parallel side walls of the convex hull 105. The limiter is connected to the information input end of the controller 6.

[0041] The trolley 403 includes wheels 4031, an axle 4032 connected to the wheels 4031, and a frame plate 4033 provided on the axle 4032. The wheels 4031 roll on the single track 4011. For example, there can be four wheels 4031. Every two wheels 4031 form a group. The wheels 4031 in the same group are connected to both ends of the axle 4032. The axle 4032 is used to support the frame plate 4033. Through holes for fixing the cylinder 404 are provided on the frame plate 4033. The trolley 403 slides from high to low along the track 401 under the action of its own gravity.

[0042] The cylinder 404 includes a cylinder barrel 4041 and a telescopic rod 4042 that slides along the cylinder barrel 4041. One end of the air source line is connected to the cylinder barrel 4041 for inputting or outputting gas into or from the cylinder barrel 4041. When gas is input, the telescopic rod 4042 is pushed out of the cylinder barrel 4041, and when gas is output, the telescopic rod 4042 retracts. The telescopic direction of the telescopic rod 4042 is perpendicular to the belt 101. The thermal resistance core rod 405 is fixed to the free end of the telescopic rod 4042. The thermal resistance core rod 405 has a remote transmission function. The central axis of the thermal resistance core rod 405 is consistent with the central axis of the telescopic rod 4042. The end of the thermal resistance core rod 405 is pointed, so that when the free end of the telescopic rod 4042 moves towards the belt 101, it can drive the thermal resistance core rod 405 to move downward synchronously and make its tip easier to insert into the reactant on the belt 101. The length of the thermal resistance core rod 405 can be, for example, 10 - 20 cm, and the length inserted into the reactant can be, for example, 3 - 8 cm. Fins 4051 are provided at the lower part of the thermal resistance core rod 405. There are, for example, two fins 4051, and the two fins 4051 are symmetrically arranged on both sides of the thermal resistance core rod 405. The fins 4051 can be, for example, triangular, square or other shapes. The bottom edge of the fins 4051 forms a cutting edge 4052, making it easier for the fins 4051 to insert into the reactant. The plane where the fins 4051 are located is perpendicular to the advancing direction of the reactant. The function of the fins 4051 is to enable the tip of the thermal resistance core rod 405 to be firmly inserted into the reactant and hold the reactant in a stable state, so that the reactant can push the thermal resistance core rod 405 to drive the trolley 403 and the cylinder 404 to move obliquely upward along the track, thus ensuring the measurement effect of the thermal resistance core rod 405. The other end of the air source line is connected to the gas storage cylinder via an air source switch 408. Both the air source switch 408 and the solenoid valve 406 are connected to the controller 6. The solenoid valve 406 is, for example, a two-position five-way solenoid valve, and the air source can be, for example, nitrogen. The principle of the solenoid valve 406 and the air source switch 408 controlling the expansion and contraction of the cylinder 404 is a common technology in the field and will not be elaborated here. The air source line and the power line are coiled in a multi-turn spiral state between the winding 407 and the cylinder 404, enabling the cylinder 404 and the thermal resistance core rod 405 to move freely along the track 401. In the initial state, the trolley 403 is located at the lowest point of the track 401 and is in contact with the low-position limiter 4022. The controller 6 controls the solenoid valve 406 and the air source switch 408, and gas enters the cylinder barrel 4041, pushing out the telescopic rod 4042. The telescopic rod 4042 drives the bottom end of the thermal resistance core rod 405 and the fins 4051 to insert into the reactant, measures the reaction temperature of the reactant and sends the temperature information to the controller 6. The controller 6 controls the heating power of the warm water tank 8 and the opening degree of the warm water valve 9 in a chain manner according to the monitored reactant temperature, thereby adjusting the temperature of the warm water entering the jacket of the box body 102. The operator adjusts the process such as the alkali ratio, feed temperature, etc. in a timely manner according to the monitored reactant temperature. The reactant pushes the thermal resistance core rod 405, the cylinder 404 and the trolley 403 to move obliquely upward along the track 401.When the trolley 403 touches the high-level limiter 4021, the high-level limiter 4021 sends information to the controller 6. The controller 6 controls the solenoid valve 406 and the air source switch 408. The gas is discharged from the cylinder barrel 4041, and the telescopic rod 4042 retracts. The thermal resistance mandrel 405 rises above the reactant. The trolley 403 moves to the initial position under its own gravity and touches the low-level limiter 4022. The controller 6 records the time when the trolley 403 touches the low-level limiter 4022. After reaching the set interval time (for example, it can be 5 - 15 minutes), the controller 6 controls the solenoid valve 406 and the air source switch 408 again, the gas enters the cylinder barrel 4041, and the cycle is carried out to measure the temperature of the reactant for the second time.

[0043] As Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 shown, the flushing assembly 5 includes a plurality of nozzles 501 arranged below the belt 101, a liquid inlet pipe 502 for conveying the flushing liquid, a liquid collecting hood 503 arranged around the nozzles 501 and used for collecting the flushing liquid, and a liquid outlet pipe connected to the bottom end of the liquid collecting hood 503.

[0044] The plurality of nozzles 501 are arranged side by side at equal intervals, and the distance between adjacent nozzles 501 ensures uniform distribution of the flow rate. The number of nozzles 501 can be 3 - 5, for example. The nozzles 501 are preferably fan-shaped nozzles to increase the spraying range. A flat nozzle opening 508 is opened at the top of the nozzle 501. The long axis of the nozzle opening 508 is perpendicular to the advancing direction of the belt 101. The nozzles 501 form a fan-shaped spray perpendicular to the advancing direction of the belt 101. The nozzles 501 face the back of the belt 101, and preferably aim at the concave surface of the belt 101. The front of the belt 101 is used to place the reactant. After the belt 101 is redirected by the driven roller 104, the front becomes the downward-facing back.

[0045] One end of the liquid inlet pipe 502 extends into the liquid collecting hood 503 and is connected to the liquid spraying main pipe 509. The liquid spraying main pipe 509 is divided into a plurality of upward-extending branch pipes, and the port of each branch pipe is connected to a nozzle 501. The end of the liquid inlet pipe 502 far from the nozzle 501 is connected to the waste liquid collection tank. The waste liquid collection tank stores the alcoholysis waste liquid or methanol solution. The alcoholysis waste liquid (the main components are 70% methanol and 28% methyl acetate) or methanol solution is used as the flushing liquid to flush the materials adhered to the belt 101. Along the conveying direction of the flushing liquid on the liquid inlet pipe 502, a liquid pump 504, a regulating valve 505, and a flow meter 506 are arranged in sequence. Both the liquid pump 504 and the regulating valve 505 are connected to the information output end of the controller 6, and the flow meter 506 is connected to the information input end of the controller 6. Preferably, after the liquid inlet pipe 502 enters the box body 102, it is divided into a plurality of branch pipes, and the plurality of branch pipes respectively extend to the front end, middle, and rear end of the belt 101, and the branch pipes enter the liquid collecting hood 503 and are connected to the liquid spraying main pipe 509.

[0046] The liquid collecting hood 503 is an inverted cone with a larger upper part and a smaller lower part. The top edge of the liquid collecting hood 503 surrounds the spray head 501. The top edge of the liquid collecting hood 503 is in contact with the belt 101. The top opening of the liquid collecting hood 503 can be rectangular, for example. The length of the top opening of the liquid collecting hood 503 is consistent with the width of the belt 101, for example. The bottom end of the liquid collecting hood 503 forms a necking 507 and is connected to one end of the liquid outlet pipe. Through holes are provided on the liquid collecting hood 503 for the inlet pipe 502 to enter the inside of the liquid collecting hood 503. The flushing liquid in the waste liquid collecting tank is pressurized by the liquid pump 504 and then transported to the spray head 501 to flush the front end, middle and rear end of the belt 101 respectively, and flush the materials adhered to the belt 101. The flushing liquid and reaction waste liquid are collected by the liquid collecting hood 503 and enter the liquid outlet pipe. The flowmeter 506 monitors the flow rate of the flushing liquid in the inlet pipe 502 and controls the regulating valve 505 in a chain manner. The material of the liquid collecting hood 503 can be a thermoplastic such as polypropylene, for example.

[0047] The liquid outlet pipe is divided into two branch pipes after passing through the filter. One of the branch pipes is connected to the waste liquid collecting tank, and the flushing liquid and reaction waste liquid are transported to the waste liquid collecting tank for secondary utilization. The other branch pipe is connected to the recovery process for recovering and treating the flushing liquid and reaction waste liquid. The liquid outlet pipe can be a rigid pipe, for example, and is used to support the liquid collecting hood 503.

[0048] The controller 6 is a programmable logic controller, which can be a PLC or a DCS, for example. It uses a type of programmable memory to store programs internally, execute user-oriented instructions such as logical operations, sequential control, timing, counting and arithmetic operations, and controls various types of machinery or production processes through digital or analog input / output. Its essence is a computer dedicated to industrial control, and its hardware structure is basically the same as that of a microcomputer. It is generally used for data processing and receiving and outputting instructions to achieve central control. Embodiment

[0049] A control process of a PVA alcoholysis system includes: (1)The controller 6 starts the electric hoist 202 in interlock and controls the electric hoist 202 to move above the manhole 107 of the first column alcoholysis machine 1. The blanking valve 205 is opened, and the PVA particles in the feeding hopper 203 are added to the concave surface of the belt 101. At the same time, the electric hoist 202 shuttles back and forth above the concave surface of the belt 101 of the first column alcoholysis machine 1, and the PVA particles are piled up into a baffle with a triangular pyramid cross-section. The length of the baffle is 120 cm, the width is 10 cm, and the height is 15 cm. In order to prevent the reaction liquid from leaking during the reaction start-up stage, according to the characteristics of the alcoholysis degree variety of the PVA product, the relative position of the belt 101 and the feeding hopper 203 can be adjusted by controlling the rotation time and rotation direction of the driving roller 103. Two or more baffles are arranged on the concave surface of the belt 101, or the baffle is constructed into an arc shape, that is, the baffle facing the running direction of the belt 101 protrudes forward, and the baffles on both sides are retracted backward, so as to better adapt to the blocking effect of the reaction liquid added to the concave surface of the belt 101. Or, in order to better construct the baffle, PVA sheet materials are first added through the feeding hopper 203 to form a baffle base layer on the concave surface of the belt 101, and then PVA particles are added, or the PVA sheet materials and particles are added at the same time, so as to form a firm baffle; Set the opening time of the blanking valve 205 to control the height of the baffle, then close the blanking valve 205, open the alcoholysis machine 1 and the first control valve 301, the belt 101 runs, and at the same time the reactants are transported to the concave surface of the belt 101. The baffle formed by piling up PVA sheet materials and particles blocks the reaction liquid to avoid the leakage of the reaction liquid, and the reaction liquid can also penetrate between the PVA particles and gradually merge with them into one body. Since the reaction liquid finally generates PVA after the alcoholysis reaction, it can not only reinforce the baffle to form a retaining wall, but also does not affect the quality of the PVA product after the alcoholysis reaction. In order to give full play to the synergistic baffle effect of the reaction liquid and the baffle formed by piling up PVA sheet materials and particles, the reaction liquid can also be poured on the baffle when constructing the baffle, so that the PVA particles and sheet materials are quickly integrated into one body. As the belt 101 runs, the reactants undergo alcoholysis reaction, from liquid to gel and then to solid. When reaching the end of the belt 101, massive PVA has been generated and becomes one body with the baffle. The baffle enters the crusher 10 directly from the discharge port at the end of the first column alcoholysis machine 1 together with the massive PVA without being taken out, which saves manpower and is safe; (2)While the blanking valve 205 is closed, the electric hoist 202 moves above the manhole 107 of the second column alcoholysis machine, and step (1) is repeated to construct a baffle in the second column alcoholysis machine. When the preparation of the baffles of all alcoholysis machines is completed, the electric hoist 202 returns to the original position; (3) The controller 6 sets the opening time of the solenoid valve 406 and the air source switch 408 to be delayed after the opening time of the alcoholysis machine 1. When the baffle passes by the thermal resistance mandrel 405, it controls the thermal resistance mandrel 405 to insert into the reactants. The controller 6 controls the solenoid valve 406 and the air source switch 408, and gas enters the cylinder barrel 4041, pushing out the telescopic rod 4042. The telescopic rod 4042 drives the bottom end of the thermal resistance mandrel 405 and the fins 4051 to insert into the reactants, measures the reaction temperature of the reactants and sends the temperature information to the controller 6. The reactants push the thermal resistance mandrel 405, the cylinder 404 and the trolley 403 to move upward along the track 401. When the trolley 403 touches the high position limiter 4021, the high position limiter 4021 sends information to the controller 6. The controller 6 controls the solenoid valve 406 and the air source switch 408, and the gas discharges from the cylinder barrel 4041, and the telescopic rod 4042 retracts, and the thermal resistance mandrel 405 rises. The trolley 403 moves to the initial position under its own gravity and touches the low position limiter 4022. The controller 6 records the time when the trolley 403 touches the low position limiter 4022. After a set interval time, the controller 6 controls the solenoid valve 406 and the air source switch 408 again, and gas enters the cylinder barrel 4041 for circulation, and measures the temperature of the reactants for the second time. The controller 6 controls the heating power of the warm water tank 8 and the opening degree of the warm water valve 9 through the monitored reaction temperature of the reactants, so as to adjust the temperature of the warm water entering the jacket of the box body 102. The operator timely adjusts the process such as the alkali ratio, the feeding temperature, etc. according to the monitored reaction temperature of the reactants; (4) The controller 6 controls the opening of the liquid pump 504 and the regulating valve 505 in a linked manner. The flushing liquid is pressurized by the liquid pump 504 and then transported to the nozzle 501 to flush the front end, the middle and the rear end of the belt 101 respectively. The flushing liquid and the reaction waste liquid are collected by the liquid collecting cover and enter the liquid outlet pipe, and are transported to the waste liquid collection tank through the liquid outlet pipe. The flowmeter 506 transmits the monitored flushing liquid flow information to the controller 6. The controller 6 controls the opening degree of the regulating valve 505 to adjust the addition amount of the flushing liquid. In the early stage of using the belt 101, the addition amount is controlled to be 300 L / h, and in the later stage, it is 1000 L / h.

[0050] The preferred embodiments of the present invention have been described above. However, the above description is not for the purpose of limitation. Those of ordinary skill in the art can make many changes or modifications to the present invention without departing from the gist and scope of the present invention. The said changes or modifications should be incorporated within the scope of the appended claims.

Claims

1. A PVA alcoholysis system, characterized in that: The invention comprises a plurality of alcoholysis machines (1) arranged in parallel and spaced relation, a feeding assembly (2) arranged above the alcoholysis machine (1) and used for forming a baffle plate, a feeding assembly used for conveying reactants to a belt (101) of the alcoholysis machine (1), a temperature measuring assembly (4) used for detecting the temperature of reactants inside the alcoholysis machine (1), a flushing assembly (5) used for flushing the belt (101) of the alcoholysis machine (1), and a controller (6); the temperature measuring assembly (4) is arranged above the belt (101) of the alcoholysis machine (1), the flushing assembly (5) is arranged below the belt (101) of the alcoholysis machine (1), and the alcoholysis machine (1), the feeding assembly (2), the feeding assembly, the temperature measuring assembly (4) and the flushing assembly (5) are all connected to the controller (6).

2. The PVA alcoholysis system according to claim 1, characterized in that: The alcoholysis machine (1) is arranged in a production workshop (7), and each row of alcoholysis machines (1) is controlled separately. The alcoholysis machine (1) comprises a casing (102) provided with a jacket, a belt (101) arranged in the casing (102), an active roller (103) connected to one end of the belt (101) and driving the belt (101) to rotate, and a driven roller (104) connected to the other end of the belt (101). The jacket is connected to a warm water tank (8) via a warm water delivery pipe, and a warm water valve (9) is arranged on the warm water delivery pipe. The warm water valve (9) and the warm water tank (8) are both connected to a controller (6). A plurality of valves are arranged on the top plate of the casing (102) along the length of the alcoholysis machine (1). The convex humps (105) are distributed in a direction, the space surrounded by the convex humps (105) is connected to the space inside the alcoholysis machine (1), the jacket of the convex humps (105) is connected to the jacket of the box body (102), the convex humps (105) include a plurality of side walls and a top wall connected to the top of the side walls, the top wall is provided with a wire outlet hole (106), the end of the top plate of the box body (102) is provided with a hand hole (107) for injecting PVA material onto the belt (101), the top plate is provided with a feed port at a distance from the hand hole (107), the belt (101) is provided with a concave surface for accommodating reactants, and the discharge port at the tail end of the alcoholysis machine (1) is connected to the pulverizer (10).

3. The PVA alcoholysis system according to claim 1 or 2, characterized in that: The feeding assembly (2) comprises a slide rail (201) fixed on the roof of the workshop and spanning all the alcoholysis machines (1), an electric hoist (202) slidably connected to the slide rail (201), a feeding hopper (203) connected to the bottom of the electric hoist (202), a feeding pipe (204) connected to the discharge port of the feeding hopper (203) and hanging downward, and a feeding valve (205) arranged on the feeding pipe (204). The length direction of the slide rail (201) is perpendicular to the length direction of the alcoholysis machine (1). The bottom of the slide rail (201) is directly opposite to the position of the hand hole (107) of the alcoholysis machine (1). The electric hoist (202) and the feeding valve (205) are both connected to the information output end of the controller (6). The feeding hopper (203) contains PVA particles, and the model of the PVA particles is the same as the model of the polyvinyl alcohol to be produced in the alcoholysis machine (1).

4. The PVA alcoholysis system according to claim 3, characterized in that: The feed assembly comprises a feed pipeline extending from a feed inlet into the alcoholysis machine (1) to above the concave surface of the belt (101) and a first control valve (301) arranged on the feed pipeline, wherein the first control valve (301) is connected to an information output end of a controller (6).

5. The PVA alcoholysis system according to claim 2, characterized in that: The temperature measuring component (4) comprises an inclined track (401) arranged in a convex bulge (105), stoppers (402) arranged at both ends of the track (401), a trolley (403) sliding along the track (401), a cylinder (404) fixed on the trolley (403), a thermal resistor core rod (405) connected to the bottom of the cylinder (404), a power line extending from a wire outlet hole (106) and connected to the thermal resistor core rod (405) and an air supply line connected to the cylinder (404), an electromagnetic valve (406) arranged on the air supply line, and a winding (407) used to wind the air supply line and the power supply line, wherein each thermal resistor core rod (405) is controlled individually.

6. The PVA alcoholysis system according to claim 5, characterized in that: A track (401) is provided in each convex hull (105), and the track (401) is gradually raised along the direction of the reactant's advance. The track (401) includes two parallel and spaced monorails (4011), and each monorail (4011) is a groove type. The stoppers (402) are touch sensors, which are respectively a high stopper (4021) and a low stopper (4022). The high stopper (4021) is connected to the raised end of the track (401), and the low stopper (4022) is connected to the other end of the track (401). The two stoppers are respectively fixed on two mutually parallel side walls of the convex hull (105), and the stoppers are connected to the information input end of the controller (6).

7. The PVA alcoholysis system according to claim 6, characterized in that: The trolley (403) comprises wheels (4031), axles (4032) connected to the wheels (4031) and a frame plate (4033) arranged on the axles (4032); the wheels (4031) roll on the monorail (4011); every two wheels (4031) form a group; the wheels (4031) in the same group are connected to both ends of the axles (4032); the axles (4032) are used to support the frame plate (4033); and a through hole for fixing the cylinder (404) is opened on the frame plate (4033).

8. The PVA alcoholysis system according to claim 7, characterized in that: The air cylinder (404) comprises a cylinder barrel (4041) and a telescopic rod (4042) sliding along the cylinder barrel (4041), one end of the air source line is connected to the cylinder barrel (4041), the telescopic direction of the telescopic rod (4042) is perpendicular to the belt (101), a thermal resistor core rod (405) is fixed to the free end of the telescopic rod (4042), the thermal resistor core rod (405) has a remote transmission function, the central axis of the thermal resistor core rod (405) is consistent with the central axis of the telescopic rod (4042), the end of the thermal resistor core rod (405) is a pointed tip, and the thermal resistor core rod (405) is a telescopic rod. The lower part of the rod (405) is provided with fins (4051), which are symmetrically arranged on both sides of the thermal resistor core rod (405), and the bottom edges of the fins (4051) form cutting edges (4052). The plane where the fins (4051) are located is perpendicular to the forward direction of the reactants. The other end of the gas source line is connected to the gas storage bottle through the gas source switch (408), and the gas source switch (408) and the solenoid valve (406) are both connected to the controller (6). The gas source line and the power line are in a state of multiple turns of spiral winding between the winding (407) and the cylinder (404).

9. The PVA alcoholysis system according to claim 1, characterized in that: The flushing assembly (5) comprises a plurality of nozzles (501) arranged below the belt (101), a liquid inlet pipe (502) for conveying flushing liquid, a liquid collecting cover (503) arranged around the nozzles (501) and for collecting flushing liquid, and a liquid outlet pipe connected to the bottom end of the liquid collecting cover (503). The nozzles (501) face the back of the belt (101). The plurality of nozzles (501) are arranged side by side and at equal distances. A flat nozzle (508) is provided on the top of the nozzle (501). The long axis of the nozzle (508) is perpendicular to the direction in which the belt (101) moves. One end of the liquid inlet pipe (502) extends into the liquid collecting cover (503). The cover (503) is connected to the liquid spraying main pipe (509), which is divided into a plurality of branch pipes extending upwards, and the port of each branch pipe is connected to a nozzle (501). The end of the liquid inlet pipe (502) away from the nozzle (501) is connected to the waste liquid collecting tank. The liquid inlet pipe (502) is provided with a liquid pump (504), a regulating valve (505) and a flow meter (506) in sequence along the conveying direction of the flushing liquid. The liquid pump (504) and the regulating valve (505) are both connected to the information output end of the controller (6), and the flow meter (506) is connected to the information input end of the controller (6).

10. The PVA alcoholysis system according to claim 9, characterized in that: The liquid collecting cover (503) is in the shape of an inverted cone with a larger upper portion and a smaller lower portion. The top edge of the liquid collecting cover (503) surrounds the nozzle (501), and the top edge of the liquid collecting cover (503) is in contact with the belt (101). The bottom end of the liquid collecting cover (503) forms a closing opening (507) and is connected to one end of the liquid outlet pipe. A through hole is opened on the liquid collecting cover (503), and the through hole allows the liquid inlet pipe (502) to enter the interior of the liquid collecting cover (503).

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