PVA alcoholysis system

Abstract

The utility model provides a PVA (polyvinyl alcohol) 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 disclosed by the utility model, reactants are not in contact with operators, so that material leakage is avoided, the service life of the belt is prolonged, the temperature is accurately measured, and the product quality is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the polyvinyl alcohol production field, concretely relates to a PVA alcoholysis system. BACKGROUND

[0002] Polyvinyl alcohol (PVA) is an important water-soluble synthetic polymer, widely used in many fields, polyvinyl alcohol is obtained by ester exchange reaction of polyvinyl acetate and methanol at a certain temperature with sodium hydroxide as catalyst, accompanied by side reaction, the reaction equation is as follows:

[0003] 1. ester exchange reaction (alcoholysis reaction):

[0004] ;

[0005] 2. saponification reaction:

[0006] ;

[0007] 3. side reaction:

[0008] .

[0009] The alcoholysis machine provides a reaction place for the above reaction, the alcoholysis machine includes a shell, a belt and a variable frequency speed regulation mechanism, the shell is a jacketed design, warm water flows in the jacket, the reaction is an exothermic reaction, the jacket adjusts the temperature in the alcoholysis machine to the required temperature for the reaction, the belt is arranged in the interior of the shell, the belt is provided with a concave surface, the concave surface is used for carrying the reactants, the reactants are reacted to produce polyvinyl alcohol at the concave surface of the belt, the belt is made of polypropylene or rubber material, the variable frequency speed regulation mechanism is used for adjusting the rotating speed of the belt, controlling the reaction time, and producing PVA with different alcoholysis degrees.

[0010] After the polyvinyl acetate methanol solution and the alkali methanol solution enter the alcoholysis machine, the reaction is carried out along with the forward movement of the belt, finally the blocky polyvinyl alcohol is generated at the end of the belt, and is transported to the pulverizer through the material outlet of the alcoholysis machine for crushing, then after dehydration by the dehydrator and drying by the drying machine, the finished product PVA is obtained, which is used in the fields of PVB (polyvinyl butyral), water-soluble fiber, various glues and the like, the tail gas (mainly methanol and methyl acetate) generated in the reaction is condensed and transported to the recovery process with the waste liquid (mainly methanol and methyl acetate) generated in the reaction for separation, hydrolysis, rectification, purification to obtain recovered methanol and recovered acetic acid for production and recycling.

[0011] Defects of prior art:

[0012] 1. The feed operation is complicated and has safety risks: because the polyvinyl acetate methanol solution and the lye are in a liquid flow state as soon as they enter the alcoholysis machine, the initial feed needs to be blocked by the alcoholysis machine blocking plate to make the liquid react to form a block-shaped PVA, which is convenient for entering the crushing device. Because the blocking plate used in the alcoholysis machine at present is an iron blocking plate and iron block, firstly, the use of the alcoholysis machine belt (the material is smooth polypropylene or rubber material) is easy to scratch, not only shortens the service life of the alcoholysis machine, but also is easy to stick after scratching; secondly, the operation is not convenient, and the iron blocking plate and iron block need to be manually operated and put into the head of the alcoholysis machine before feeding, and then manually operated and taken out from the tail of the alcoholysis machine after the material is reacted and formed, but because the blocking plate and iron block are heavy, and there is PVA adhesion, it is difficult to take out, and if it cannot be taken out in time, it will cause the machine to stop, and if the blocking plate enters the pulverizer and collides with the pulverizer blade by accident, a major safety accident will occur; thirdly, because the methanol content in the alcoholysis machine is high, if the operation is not proper during the process of taking out the blocking plate, a fire or explosion accident (similar accidents in the industry) will occur; fourthly, the two sides of the alcoholysis machine inlet are smooth curved surfaces, and if the sealing is not strict, material leakage will occur, and after the material leakage, the formed PVA is too thin to enter the pulverizer for crushing, causing the machine to stop;

[0013] 2. The service life of the alcoholysis machine belt is short: the alcoholysis machine belt used in the industry at present has two materials, one is polypropylene and the other is rubber material, no matter which material will have a phenomenon of sticking material, the material stuck on the belt will change a lot in quality due to overreaction for a long time, and finally will be brought into the product (industry called white point material). The material stuck on the belt not only affects the product quality, but also damages the belt when it falls off; if it is not found or the belt is not replaced in time, it will cause material leakage and equipment damage accident, and if not handled properly, even a fire or explosion accident will occur;

[0014] 3. As we all know, the reaction temperature is one of the important factors of chemical reaction, and the accuracy and stability of the temperature directly affect the reaction degree and the final result, the alcoholysis reaction is an exothermic reaction, and there are two aspects to control the reaction temperature in the industry at present, 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 alcoholysis machine temperature. 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, the reaction will start and heat will be released, and according to the change of raw material concentration and flow, the reaction temperature will change, the method for measuring the alcoholysis machine temperature in the industry at present is to detect the space temperature above the belt alcoholysis machine box, but such detection cannot accurately measure the temperature of the material on the belt, so the process (feed temperature, alkali ratio, etc.) cannot be adjusted in time, resulting in wide distribution of the final product alcoholysis degree and unstable quality. The utility model discloses

[0015] The PVA alcoholysis system provided by the utility model avoids contact between the reactant and the operator, avoids material leakage, prolongs the service life of the belt, accurately measures the temperature, and improves product quality.

[0016] The utility model adopts the technical scheme as follows:

[0017] A PVA alcoholysis system, which comprises multiple rows of alcoholysis machines arranged side by side at intervals, a feeding assembly arranged above the alcoholysis machines and used for forming a blocking plate, a feeding assembly used for conveying the reactant to the belt of the alcoholysis machine, a temperature measuring assembly used for detecting the temperature of the reactant in the alcoholysis machine, a flushing assembly used for flushing the belt of the alcoholysis machine, and a controller, wherein the temperature measuring assembly is arranged above the belt of the alcoholysis machine, the flushing assembly is arranged below the belt of the alcoholysis machine, and the alcoholysis machine, the feeding assembly, the temperature measuring assembly, and the flushing assembly are all connected with the controller.

[0018] Further, the alcoholysis machine can be 2-10 rows, preferably 5-8 rows, and the multiple rows of alcoholysis machines are arranged at equal intervals, for example. The alcoholysis machine is arranged in a production workshop and is controlled individually. The alcoholysis machine comprises a box body provided with a jacket, a belt arranged in 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 is used for temperature control by adjusting the amount of steam, process water, and condensate water from a dryer through an adjusting valve. A warm water valve is arranged on the warm water conveying pipe. The warm water valve and the warm water tank are connected with the controller. A plurality of convex blocks are arranged on the top plate of the box body and distributed along the length direction of the alcoholysis machine. The convex blocks can be 3-10, preferably 5-8. The convex block is a rectangular cuboid structure with a jacket. The length of the convex block can be 2.5-3 m, the width can be 5-15 cm, and the height can be 20-50 cm. The space surrounded by the convex block is communicated with the space inside the alcoholysis machine. The jacket of the convex block is communicated with the jacket of the box body. The convex block comprises 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. An access hole is arranged at the end of the top plate of the box body and used for injecting PVA material onto the belt. A feeding port is arranged on the top plate at a distance from the access hole. The feeding port is closer to the driving roller than the access hole. The belt is provided with a concave surface for accommodating the reactant. The discharge port at the tail end of the alcoholysis machine is connected with a pulverizer.

[0019] Further, the feeding assembly comprises a slide rail fixed on the roof of the workshop and crossing all the 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 downward, a feeding valve arranged on the feeding pipe, the length direction of the slide rail is perpendicular to the length direction of the alcoholysis machine, the slide rail is opposite to the position of the hand hole of the alcoholysis machine, 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 type of the PVA particles or sheets is the same as the type of the polyvinyl alcohol to be produced by the alcoholysis machine, the feeding pipe moves above the straight line where the hand hole is located, and the PVA particles or sheets in the feeding hopper are added to the belt through the feeding pipe, the controller controls the moving position of the electric hoist on the slide rail and controls the opening and closing of the feeding valve.

[0020] Further, the feeding assembly comprises a feeding pipe extending into the alcoholysis machine from the feeding port to above the concave surface of the belt and a first control valve arranged on the feeding pipe, the first control valve is connected to the information output end of the controller, the first control valve is preferably arranged on the feeding pipe outside the alcoholysis machine, and preferably, the feeding pipe comprises polyvinyl acetate methanol solution conveying pipes and alkali methanol solution conveying pipes arranged side by side, and the polyvinyl acetate methanol solution conveying pipes and the alkali methanol solution conveying pipes are each provided with a first control valve.

[0021] Further, the temperature measuring assembly comprises an inclined track arranged in the convex block, limiters arranged at both ends of the track, a trolley sliding along the track, a gas cylinder fixed on the trolley, a thermal resistance core rod connected below the gas cylinder, a power supply line extending into the thermal resistance core rod from the outlet hole and connected to the thermal resistance core rod, and a gas source line connected to the gas cylinder, an electromagnetic valve arranged on the gas source line, a winding for winding the gas source line and the power supply line, and each thermal resistance core rod is controlled separately.

[0022] Further, a track is arranged in each convex block, the track gradually rises along the direction in which the reactants advance, the track comprises two single tracks arranged in parallel and spaced apart, each single track is a groove type, the limiters are touch sensors, the limiters are two, which are a high-level limiter and a low-level limiter, the high-level limiter is connected to the rising end of the track, the low-level limiter is connected to the other end of the track, the two limiters are fixed on two mutually parallel side walls of the convex block, and the limiters are connected to the information input end of the controller.

[0023] Further, the trolley comprises wheels, an axle connected to the wheels, and a frame plate arranged on the axle, the wheels roll on the single track, the wheels can be four for example, and each two wheels form a group, the wheels in the same group are connected to the two ends of the axle, the axle is used to support the frame plate, the frame plate is provided with through holes for fixing the gas cylinder, and the trolley slides along the track from high to low under the action of its own gravity.

[0024] Further, the cylinder comprises a cylinder barrel and a telescopic rod sliding along the cylinder barrel, one end of the gas source line is connected with the cylinder barrel, for inputting or outputting gas into or out of the cylinder barrel, when the gas is inputted, the telescopic rod is pushed out of the cylinder barrel, when the gas is outputted, the telescopic rod is retracted, 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, 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 a sharp head, so that when the free end of the telescopic rod moves towards the belt, the thermal resistance core rod can be driven to descend synchronously and the sharp head can be more easily inserted into the reactant on the belt, the length of the thermal resistance core rod can be 10-20 cm for example, the length of the thermal resistance core rod inserted into the reactant can be 3-8 cm for example, the lower part of the thermal resistance core rod is provided with fins, the fins can be two for example, the two fins are symmetrically arranged on both sides of the thermal resistance core rod, the fins can be triangular or square in shape for example, the bottom edge of the fin forms a cutting edge, so that the fin can be more easily inserted 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 firmly insert the sharp head of the thermal resistance core rod into the reactant and hold the reactant in a stable state, so that the reactant can drive the thermal resistance core rod, the trolley and the cylinder to move obliquely upwards along the track, the other end of the gas source line is connected with the gas storage bottle through a gas source switch, the gas source switch and the electromagnetic valve are connected with the controller, the electromagnetic valve uses a two-position five-way electromagnetic valve for example, the gas source can be nitrogen for example, the principle of the electromagnetic valve and the gas source switch controlling the telescopic cylinder is a common technology in the art, which will not be described in detail, the gas source line and the power line are spirally wound between the winding and the cylinder in multiple turns, so that the cylinder and the thermal resistance core rod can move freely along the track, in the initial state, the trolley is located at the lowest point of the track, the trolley is in contact with the low-position limiter, the controller controls the electromagnetic valve and the gas source switch, the gas enters the cylinder barrel, the telescopic rod is pushed out, the bottom end of the thermal resistance core rod and the fin are inserted into the reactant by the telescopic rod, the reaction temperature of the reactant is measured and the temperature information is sent 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, so as to adjust the temperature of the warm water entering the box jacket, the operator adjusts the process such as base ratio, feed temperature and the like in time according to the monitored reactant temperature, the reactant drives the thermal resistance core rod, the cylinder and the trolley to move obliquely upwards along the track, when the trolley touches the high-position limiter, the high-position limiter sends information to the controller, the controller controls the electromagnetic valve and the gas source switch, the gas is discharged from the cylinder barrel, the telescopic rod is retracted, the thermal resistance core rod is lifted to above the reactant, the trolley moves to the initial position under the action of its own gravity and touches 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 5-15 minutes for example), the controller controls the electromagnetic valve and the gas source switch again, the gas enters the cylinder barrel, and the cycle is repeated, the temperature of the reactant is measured for the second time.

[0025] Further, the flushing assembly comprises a plurality of spray heads arranged below the belt, a liquid inlet pipe for conveying the flushing liquid, a liquid collecting cover arranged around the spray heads for collecting the flushing liquid, and a liquid outlet pipe connected to the bottom end of the liquid collecting cover.

[0026] Further, the plurality of spray heads are arranged side by side at equal distances, the distance between adjacent spray heads ensures uniform distribution of the flow, the spray heads may be, for example, 3-5, and the spray heads are preferably fan-shaped spray heads, which increase the spraying range, the top of the spray head is provided with a flat-shaped spray port, the long axis of the spray port is perpendicular to the direction of belt advancement, the spray head faces the back surface of the belt, and the spray head is preferably aligned with the concave surface of the belt, the front surface of the belt is used for placing the reactants, the belt is redirected by the driven roller, and the front surface becomes the downward back surface, one end of the liquid inlet pipe extends into the liquid collecting cover and is connected to the liquid spraying main pipe, the liquid spraying main pipe is divided into a plurality of upward extending branch pipes, the ports of each branch pipe are connected to a spray head, the end of the liquid inlet pipe away from the spray head is connected to a waste liquid collecting tank, the waste liquid collecting tank stores alcoholysis waste liquid or methanol solution, the alcoholysis waste liquid (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, 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 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 enters the box body and is divided into a plurality of branch pipes, 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 cover and are connected to the liquid spraying main pipe.

[0027] Further, the liquid collecting cover is in the shape of an inverted cone with a large top and a small bottom, the top edge of the liquid collecting cover surrounds the spray heads, the top edge of the liquid collecting cover is attached to the belt, the top of the liquid collecting cover is provided with an opening, for example, in the shape of a rectangle, the length of the opening of the top of the liquid collecting cover is, for example, consistent with the width of the belt, the bottom end of the liquid collecting cover is formed into a closed end and is connected to one end of the liquid outlet pipe, the liquid collecting cover is provided with a through hole, the through hole is used for the liquid inlet pipe to enter the inside of the liquid collecting cover, the flushing liquid in the waste liquid collecting tank is pressurized by the liquid pump and is then conveyed to the spray heads to flush the front end, the middle and the rear end of the belt, and to flush the materials adhered to the belt, the flushing liquid and the reaction waste liquid are collected by the liquid collecting cover and are then introduced into the liquid outlet pipe, the flow meter monitors the flow of the flushing liquid in the liquid inlet pipe and controls the regulating valve in a chained manner, and the material of the liquid collecting cover may be, for example, thermoplastic plastic such as polypropylene.

[0028] Further, the liquid outlet pipe is divided into two branch pipes after passing through a filter, one of the branch pipes is connected to the waste liquid collecting tank, the flushing liquid and the reaction waste liquid are conveyed to the waste liquid collecting tank for secondary use, and the other branch pipe is connected to a recovery process for recovering and treating the flushing liquid and the reaction waste liquid, and the liquid outlet pipe may be, for example, a hard pipe for supporting the liquid collecting cover.

[0029] Further, the controller is a programmable logic controller.

[0030] The beneficial effects of the utility model are as follows:

[0031] The PVA alcoholysis system provided by the utility model prolongs the service life of the alcoholysis machine belt, realizes automation from the feeding operation to the flushing operation, not only reduces the labor intensity of personnel, but also improves the safety factor, guarantees the stability of the alcoholysis reaction, improves the product quality and eliminates the production safety hidden danger. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is the front view of the PVA alcoholysis system of the utility model.

[0033] Figure 2 It is the side view of the PVA alcoholysis system of the utility model.

[0034] Figure 3 It is the connection diagram of the liquid collecting cover, the spray head and the liquid inlet pipe. Figure 1 .

[0035] Figure 4 It is the connection diagram of the liquid collecting cover, the spray head and the liquid inlet pipe. Figure 2 .

[0036] Figure 5 It is the schematic view of the spray head.

[0037] Figure 6 It is the process schematic view of the hot resistance core rod moving along with the reactant on the belt.

[0038] Figure 7 It is the internal structure schematic view of the convex hull.

[0039] Figure 8 It is the front view of Figure 7 .

[0040] Figure 9 It is the schematic view of the trolley being connected with the cylinder.

[0041] Figure 10 is an enlarged view of A in Figure 9

[0042] Figure 11 is a structural schematic view of a track.

[0043] Figure 12 is a control block diagram of a PVA alcoholysis system.

[0044] Reference signs:

[0045] 1-alcoholysis machine, 101-belt, 102-box body, 103-driving roller, 104-following roller, 105-bulge, 106-outlet hole, 107-hand hole,

[0046] 2-feeding assembly, 201-slideway, 202-electric hoist, 203-feeding hopper, 204-discharging pipe, 205-discharging valve,

[0047] 301-first control valve,

[0048] 4-temperature measuring assembly, 401-track, 4011-single track, 402-limiter, 4021-high position limiter, 4022-low position limiter, 403-trolley, 4031-wheel, 4032-axle, 4033-carriage plate, 404-cylinder, 4041-cylinder barrel, 4042-telescopic rod, 405-thermocouple rod, 4051-fin, 4052-cutting blade, 406-solenoid valve, 407-winding, 408-air source switch,

[0049] 5-flushing assembly, 501-sprinkler, 502-liquid inlet pipe, 503-liquid collecting cover, 504-liquid pump, 505-regulating valve, 506-flow meter, 507-closing, 508-spraying opening, 509-liquid spraying main pipe,

[0050] 6-controller, 7-production workshop, 8-warm water tank, 9-warm water valve, 10-crusher. DETAILED DESCRIPTION

[0051] The utility model will be described in detail below with reference to the drawings and in combination with embodiments.

[0052] As Figures 1-12 ​As shown in the figure, a PVA alcoholysis system includes a plurality 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 blocking plate, a feeding assembly for conveying reactants to the belt 101 of the alcoholysis machine 1, a temperature measuring assembly 4 for detecting the temperature of the reactants inside the alcoholysis machine 1, a flushing assembly 5 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, the temperature measuring assembly 4, and the flushing assembly 5 are connected to the controller 6.

[0053] As shown in the figure, Figure 1 , Figure 2 The alcoholysis machine 1 may be, for example, 2-10 columns, preferably 5-8 columns. The plurality of alcoholysis machines 1 may be, for example, arranged at equal intervals. The alcoholysis machine 1 is arranged in a production workshop 7. Each column of alcoholysis machines 1 is controlled separately. The alcoholysis machine 1 includes a jacketed box 102, a belt 101 arranged in the box 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 communicated with a warm water tank 8 through a warm water conveying pipe. The warm water tank 8 is temperature-controlled by adjusting the amount of steam and process water and dryer condensate added through a regulating valve. A warm water valve 9 is arranged on the warm water conveying pipe. The warm water valve 9 and the warm water tank 8 are connected to the controller 6. A plurality of convex hulls 105 are arranged on the top plate of the box 102 and distributed along the length direction of the alcoholysis machine 1. The convex hulls 105 may be, for example, 3-10, preferably 5-8. The convex hulls 105 are rectangular cuboid structures with jackets. The length of the convex hulls 105 may be, for example, 2.5-3 m, the width may be, for example, 5-15 cm, and the height may be, for example, 20-50 cm. The space enclosed by the convex hulls 105 is communicated with the space inside the alcoholysis machine 1. The jacket of the convex hull 105 is communicated with the jacket of the box 102. The convex hull 105 includes 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. An end of the top plate of the box 102 is provided with a hand hole 107 for injecting PVA materials onto the belt 101. A feeding port is arranged on the top plate at a distance from the hand hole 107. The feeding port is closer to the driving roller 103 than the hand hole 107. The belt 101 is provided with a concave surface for accommodating reactants. The discharge port at the tail end of the alcoholysis machine 1 is connected to a crusher 10.

[0054] As shown in the figure, Figure 1 , Figure 2As shown in the drawings, the feeding assembly 2 comprises a slide rail 201 fixed on the roof of the workshop and across all 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 with the discharge port of the feeding hopper 203 and hanging downward, a feeding valve 205 arranged in the feeding pipe 204, the length direction of the slide rail 201 is perpendicular to the length direction of the alcoholysis machine 1, the position of the slide rail 201 below the hand hole 107 of the alcoholysis machine 1, the electric hoist 202 and the feeding valve 205 are connected with the information output end of the controller 6, the feeding hopper 203 contains PVA particles or PVA sheet materials or a mixture of PVA particles and PVA sheet materials, the model of the PVA particles or sheet materials is the same as the model of the polyvinyl alcohol to be produced on the alcoholysis machine 1, the feeding pipe 204 moves directly above the straight line where the hand hole 107 is located, the PVA particles or sheet materials in the feeding hopper 203 are added 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 controls the opening and closing of the feeding valve 205.

[0055] The feeding assembly comprises a feeding pipe extending into the alcoholysis machine 1 from the feeding port to above the concave surface of the belt 101 and a first control valve 301 arranged on the feeding pipe, the first control valve 301 is connected with the information output end of the controller 6, the first control valve 301 is preferably arranged on the feeding pipe outside the alcoholysis machine 1, preferably, the feeding pipe comprises polyvinyl acetate methanol solution conveying pipe and alkali methanol solution conveying pipe arranged side by side, the polyvinyl acetate methanol solution conveying pipe and the alkali methanol solution conveying pipe are both provided with the first control valve 301.

[0056] As shown in the drawings, Figure 1 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 As shown in the drawings, the temperature measuring assembly 4 comprises an inclined track 401 arranged in the convex 105, a limit stop 402 arranged at both ends of the track 401, a trolley 403 sliding along the track 401, a gas cylinder 404 fixed on the trolley 403, a thermocouple rod 405 connected below the gas cylinder 404, a power supply line extending into the thermocouple rod 405 from the outlet hole 106 and a gas source line connected with the gas cylinder 404, an electromagnetic valve 406 arranged on the gas source line, a winding 407 for winding the gas source line and the power supply line, and each thermocouple rod 405 is controlled separately.

[0057] Each convex bump 105 is provided with a track 401, which is gradually raised along the direction of the reactant advancing, the track 401 comprises two parallel and spaced single tracks 4011, each single track 4011 is a groove type, the limiters 402 are touch sensors, the limiters 402 are two, which are high limiters 4021 and low limiters 4022 respectively, the high limiters 4021 are connected with the raised end of the track 401, the low limiters 4022 are connected with the other end of the track 401, the two limiters are respectively fixed on the two parallel side walls of the convex bump 105, and the limiters are connected with the information input end of the controller 6.

[0058] The trolley 403 comprises wheels 4031, axles 4032 connected with the wheels 4031 and frame plates 4033 arranged on the axles 4032, the wheels 4031 roll on the single tracks 4011, the wheels 4031 may be four for example, every two wheels 4031 are a group, the wheels 4031 in the same group are connected with the two ends of the axle 4032, the axle 4032 is used for supporting the frame plate 4033, the frame plate 4033 is provided with through holes for fixing the cylinders 404, and the trolley 403 slides along the track 401 from high to low under the action of its own gravity.

[0059] The cylinder 404 comprises a cylinder barrel 4041 and a telescopic rod 4042 sliding along the cylinder barrel 4041, one end of the gas source line is connected with the cylinder barrel 4041, for inputting or outputting gas into or out of the cylinder barrel 4041, when the gas is input, the telescopic rod 4042 is pushed out of the cylinder barrel 4041, and when the gas is output, the telescopic rod 4042 is retracted, 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 a sharp head, 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 the sharp head more easily inserted into the reactant on the belt 101, the length of the thermal resistance core rod 405 can be 10-20 cm for example, the length of the inserted reactant can be 3-8 cm for example, the lower part of the thermal resistance core rod 405 is provided with fins 4051, the fins 4051 can be two for example, the two fins 4051 are symmetrically arranged on both sides of the thermal resistance core rod 405, the fins 4051 can be triangular or square in shape for example, the bottom edge of the fin 4051 forms a cutting edge 4052, so that the fin 4051 is more easily inserted into the reactant, the plane where the fin 4051 is located is perpendicular to the advancing direction of the reactant, the function of the fin 4051 is to firmly insert the sharp head of the thermal resistance core rod 405 into the reactant and hold the reactant in a stable state, so that the reactant can drive the thermal resistance core rod 405, the trolley 403 and the cylinder 404 to move obliquely upward along the track, thereby ensuring the measurement effect of the thermal resistance core rod 405, the other end of the gas source line is connected with the gas storage bottle through the gas source switch 408, the gas source switch 408 and the electromagnetic valve 406 are connected with the controller 6, the electromagnetic valve 406 uses a two-position five-way electromagnetic valve for example, the gas source can be nitrogen for example, the principle of the electromagnetic valve 406 and the gas source switch 408 controlling the telescoping of the cylinder 404 is a common technology in the art, which will not be described in detail, the gas source line and the power line are in a multi-turn spiral winding state between the winding 407 and the cylinder 404, so that the cylinder 404 and the thermal resistance core rod 405 can move freely along the track 401, in the initial state, the trolley 403 is located at the lowest point of the track 401, the trolley 403 is in contact with the low-position limiter 4022, the controller 6 controls the electromagnetic valve 406 and the gas source switch 408, gas enters the cylinder barrel 4041, pushing out the telescopic rod 4042, the bottom end of the telescopic rod 4042 and the fin 4051 of the thermal resistance core rod 405 are inserted into the reactant, the reaction temperature of the reactant is measured and the temperature information is sent 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 through the monitored reactant temperature, thereby adjusting the warm water temperature entering the jacket of the box body 102, the operator adjusts the process such as base ratio, feed temperature and the like in time according to the monitored reactant temperature, the reactant drives 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 position limiter 4021, the high position limiter 4021 sends information to the controller 6, the controller 6 controls the electromagnetic valve 406 and the gas source switch 408, the gas is discharged from the cylinder 4041, the telescopic rod 4042 is retracted, the thermal resistance core rod 405 is lifted to the upper side of the reactant, and the trolley 403 moves to the initial position under the action of 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, and after reaching the set interval time (for example, it can be 5-15 minutes), the controller 6 controls the electromagnetic valve 406 and the gas source switch 408 again, the gas enters the cylinder 4041, and the cycle is performed, and the temperature of the reactant is measured for the second time.

[0060] As shown in Figure 2 , Figure 3 , Figure 4 , Figure 5 The flushing assembly 5 includes a plurality of spray heads 501 arranged below the belt 101, a liquid inlet pipe 502 for conveying the flushing liquid, a liquid collecting cover 503 arranged around the spray heads 501 and used for collecting the flushing liquid, and a liquid outlet pipe connected with the bottom end of the liquid collecting cover 503.

[0061] The plurality of spray heads 501 are arranged side by side at equal distances, the distance between adjacent spray heads 501 ensures uniform distribution of flow, and the spray heads 501 can be, for example, 3-5. The spray heads 501 are preferably fan-shaped spray heads, which increase the spraying range. The top of the spray head 501 is provided with a flat-shaped spray port 508, the long axis of the spray port 508 is perpendicular to the advancing direction of the belt 101, the spray head 501 forms a fan-shaped spray perpendicular to the advancing direction of the belt 101, and the spray head 501 is directly opposite to the back surface of the belt 101. The spray head 501 is preferably aligned with the concave surface of the belt 101, and the front surface of the belt 101 is used for placing the reactant. After the belt 101 is redirected by the driven roller 104, the front surface becomes the downward back surface.

[0062] One end of the liquid inlet pipe 502 extends into the liquid collecting cover 503 and is connected with a liquid spraying main pipe 509. The liquid spraying main pipe 509 is divided into a plurality of upward extending branch pipes, the port of each branch pipe is connected with a spray head 501, and the end of the liquid inlet pipe 502 away from the spray head 501 is connected with a waste liquid collecting tank. The waste liquid collecting tank stores alcoholysis waste liquid or methanol solution. The alcoholysis waste liquid (main components are 70% methanol and 28% methyl acetate) or the methanol solution is used as the flushing liquid to flush the material adhered to the belt 101. A liquid pump 504, an adjusting valve 505 and a flow meter 506 are sequentially arranged on the liquid inlet pipe 502 along the conveying direction of the flushing liquid. The liquid pump 504 and the adjusting valve 505 are connected with the information output end of the controller 6, and the flow meter 506 is connected with the information input end of the controller 6. Preferably, the liquid inlet pipe 502 enters the box body 102 and is divided into a plurality of branch pipes, the branch pipes extend to the front end, the middle and the rear end of the belt 101 respectively, and the branch pipes enter the liquid collecting cover 503 and are connected with the liquid spraying main pipe 509.

[0063] The liquid collecting cover 503 is a reverse cone with a large top and a small bottom. The top edge of the liquid collecting cover 503 surrounds the spray head 501, and the top edge of the liquid collecting cover 503 is attached to the belt 101. The top opening of the liquid collecting cover 503 is, for example, rectangular, and the length of the top opening of the liquid collecting cover 503 is, for example, consistent with the width of the belt 101. The bottom end of the liquid collecting cover 503 forms a narrowing 507 and is connected to one end of the liquid outlet pipe. The liquid collecting cover 503 has a through hole for the liquid inlet pipe 502 to enter the interior of the liquid collecting cover 503. The flushing liquid in the waste liquid collection tank is pressurized by the liquid pump 504 and delivered to the spray head 501 to flush the front end, middle, and rear end of the belt 101 and the material adhered to the belt 101. The flushing liquid and the reaction waste liquid are collected by the liquid collecting cover 503 and enter the liquid outlet pipe. The flow meter 506 monitors the flow of the flushing liquid in the liquid inlet pipe 502 and controls the regulating valve 505. The material of the liquid collecting cover 503 is, for example, thermoplastic plastic such as polypropylene.

[0064] The liquid outlet pipe is divided into two branches after passing through the filter. One branch is connected to the waste liquid collection tank, and the flushing liquid and the reaction waste liquid are delivered to the waste liquid collection tank for secondary use. The other branch is connected to the recovery process for recovering and processing the flushing liquid and the reaction waste liquid. The liquid outlet pipe is, for example, a hard pipe for supporting the liquid collecting cover 503.

[0065] The controller 6 is a programmable logic controller, which is, for example, a PLC or a DCS. It uses a programmable memory to store programs, perform logic operations, sequential control, timing, counting, and arithmetic operations, and control various types of machinery or production processes through digital or analog input / output. It is essentially a computer dedicated to industrial control, with a hardware structure basically the same as a microcomputer, generally used for data processing and receiving and outputting instructions, for central control. Embodiment

[0066] A control process of a PVA alcoholysis system includes:

[0067] (1) The controller 6 interlocks the starting of the electric hoist 202 and controls the electric hoist 202 to move above the hand hole 107 of the first row of alcoholysis machines 1, opens the discharge valve 205, and adds the PVA particles in the feeding hopper 203 to the concave surface of the belt 101, while controlling the electric hoist 202 to move to and fro above the concave surface of the belt 101 of the first row of alcoholysis machines 1, and the PVA particles are piled 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 start of the reaction, the relative position of the belt 101 and the feeding hopper 203 can also be adjusted by controlling the rotation time and direction of the driving roller 103 according to the alcoholysis degree variety characteristics of the PVA product, setting two or more baffles on the concave surface of the belt 101, or constructing the baffle into an arc shape, that is, the baffle facing the forward direction of the belt 101 is convex, and the baffles on both sides are concave, 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, the PVA sheet material is first added through the feeding hopper 203 to form a baffle base layer on the concave surface of the belt 101, and then the PVA particles are added, or the PVA sheet material and particles are added at the same time, so as to form a firm baffle; the opening time of the discharge valve 205 is set to control the height of the baffle, and then the discharge valve 205 is closed, the alcoholysis machine 1 and the first control valve 301 are opened, and the belt 101 is operated, while the reactant is transported to the concave surface of the belt 101. The baffle formed by the PVA sheet material and particles blocks the reaction liquid, preventing the reaction liquid from leaking, and the reaction liquid can also penetrate between the PVA particles and gradually integrate with them. Since the reaction liquid eventually forms PVA after the alcoholysis reaction, not only can the baffle be reinforced to form a baffle wall, but also the quality of the PVA product after the alcoholysis reaction will not be affected. In order to fully utilize the synergistic blocking effect of the reaction liquid and the baffle formed by the PVA sheet material and particles, the reaction liquid can be poured on the baffle when the baffle is constructed, so that the PVA particles and sheet material quickly integrate. As the belt 101 runs, the reactant undergoes an alcoholysis reaction, from liquid to gel to solid, and when it reaches the end of the belt 101, it has formed a block of PVA and has become one with the baffle. The baffle, together with the block of PVA, directly enters the pulverizer 10 from the discharge port at the tail end of the first row of alcoholysis machines 1 without the need to be removed, saving manpower and ensuring safety.

[0068] (2) At the same time that the discharge valve 205 is closed, the electric hoist 202 moves above the hand hole 107 of the second row of alcoholysis machines, and step (1) is repeated to construct the baffle in the second row of alcoholysis machines. When the baffles of all the alcoholysis machines are prepared, the electric hoist 202 returns to the original position.

[0069] (3) The controller 6 sets the opening time of the electromagnetic valve 406 and the air source switch 408 to be later than the opening time of the alcoholysis machine 1. When the blocking plate passes through the hot resistance core rod 405, the controller 6 controls the electromagnetic valve 406 and the air source switch 408, and the gas enters the cylinder 4041, pushing the telescopic rod 4042, which drives the bottom end of the hot resistance core rod 405 and the fin 4051 to insert into the reactant. The reaction temperature of the reactant is measured and the temperature information is sent to the controller 6. The reactant pushes the hot resistance core rod 405, the air cylinder 404 and the trolley 403 to move upwards along the track 401. When the trolley 403 touches the high-limit stopper 4021, the high-limit stopper 4021 sends information to the controller 6. The controller 6 controls the electromagnetic valve 406 and the air source switch 408, and the gas is discharged from the cylinder 4041. The telescopic rod 4042 retracts, the hot resistance core rod 405 rises, and the trolley 403 moves to the initial position under the action of its own gravity and touches the low-limit stopper 4022. The controller 6 records the time when the trolley 403 touches the low-limit stopper 4022. After a set interval of time, the controller 6 controls the electromagnetic valve 406 and the air source switch 408 again, and the gas enters the cylinder 4041 to perform a cycle. The temperature of the reactant is measured 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 temperature of the reactant, so as to adjust the temperature of the warm water entering the jacket of the box body 102. The operator adjusts the process such as alkali ratio and feed temperature in a timely manner according to the monitored temperature of the reactant.

[0070] (4) The controller 6 controls the opening of the liquid pump 504 and the adjusting valve 505. The flushing liquid is pressurized by the liquid pump 504 and then delivered to the spray head 501. The front end, middle and rear end of the belt 101 are flushed respectively. The flushing liquid and the reaction waste liquid are collected by the liquid collecting cover and then delivered 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 adjusting valve 505 to adjust the addition amount of the flushing liquid. In the early stage of use of the belt 101, the addition amount is controlled to be 300 L / h, and in the later stage, the addition amount is controlled to be 1000 L / h.

[0071] The above describes the preferred embodiments of the present application, however, the above description is not used for the purpose of limitation. Those skilled in the art can make many changes or modifications to the present application without departing from the spirit and scope of the present application. The changes or modifications should be included in the scope of the appended claims.

Claims

1. A PVA alcoholysis system characterized by, The device comprises a plurality of alcoholysis machines (1) arranged side by side, a feeding assembly (2) arranged above the alcoholysis machines (1) and used for forming a material blocking plate, a feeding assembly used for conveying reactants to the belts (101) of the alcoholysis machines (1), a temperature measuring assembly (4) used for detecting the temperature of the reactants in the alcoholysis machines (1), a flushing assembly (5) used for flushing the belts (101) of the alcoholysis machines (1), and a controller (6). The temperature measuring assembly (4) is arranged above the belts (101) of the alcoholysis machines (1), the flushing assembly (5) is arranged below the belts (101) of the alcoholysis machines (1), and the alcoholysis machines (1), the feeding assembly, the temperature measuring assembly (4) and the flushing assembly (5) are connected to the controller (6).

2. The PVA alcoholysis system of claim 1, wherein, The alcoholysis machines (1) are arranged in a production workshop (7), each column of alcoholysis machines (1) is controlled independently, and each alcoholysis machine (1) comprises a box (102) provided with a jacket, a belt (101) arranged in the box (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 communicated with a warm water tank (8) through a warm water conveying pipe, a warm water valve (9) is arranged on the warm water conveying pipe, and the warm water valve (9) and the warm water tank (8) are connected to the controller (6). A plurality of convex blocks (105) are arranged on the top plate of the box (102) and distributed along the length direction of the alcoholysis machine (1). The space surrounded by the convex blocks (105) is communicated with the space inside the alcoholysis machine (1). The jacket of the convex block (105) is communicated with the jacket of the box (102). The convex block (105) comprises 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 (102) is provided with a hand hole (107) for injecting PVA material onto the belt (101). A feeding port is arranged on the top plate at a distance from the hand hole (107). The belt (101) is provided with a concave surface for accommodating reactants. The discharge port at the tail end of the alcoholysis machine (1) is connected to a crusher (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 to the roof of the workshop and crossing 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 discharging pipe (204) connected to the discharge port of the feeding hopper (203) and hanging downward, and a discharging valve (205) arranged in the discharging pipe (204). The length direction of the slide rail (201) is perpendicular to the length direction of the alcoholysis machine (1). The position of the slide rail (201) below corresponds to the position of the hand hole (107) of the alcoholysis machine (1). The electric hoist (202) and the discharging valve (205) are connected to the information output end of the controller (6). The feeding hopper (203) is filled with PVA particles. The model of the PVA particles is the same as the model of the polyvinyl alcohol to be produced on the alcoholysis machine (1).

4. The PVA alcoholysis system of claim 3, wherein, The feeding assembly comprises a feeding pipe extending into the alcoholysis machine (1) from the feeding port to above the concave surface of the belt (101) and a first control valve (301) arranged on the feeding pipe, and the first control valve (301) is connected with the information output end of the controller (6).

5. The PVA alcoholysis system of claim 2, wherein, The temperature measuring assembly (4) comprises an inclined track (401) arranged in the convex bump (105), limiters (402) arranged at two ends of the track (401), a trolley (403) sliding along the track (401), a gas cylinder (404) fixed on the trolley (403), a thermal resistance core rod (405) connected below the gas cylinder (404), a power supply wire extending into the outlet hole (106) and connected with the thermal resistance core rod (405), a gas source wire connected with the gas cylinder (404), an electromagnetic valve (406) arranged on the gas source wire, a winding (407) for winding the gas source wire and the power supply wire, and each thermal resistance core rod (405) is controlled independently.

6. The PVA alcoholysis system of claim 5, wherein, Each convex bump (105) is provided with a track (401), the track (401) gradually rises along the direction of the reactant advancing, the track (401) comprises two single tracks (4011) arranged in parallel and spaced apart, each single track (4011) is a groove type, the limiters (402) are touch sensors, and the limiters (402) are high limiters (4021) and low limiters (4022) respectively, the high limiters (4021) are connected with the rising end of the track (401), the low limiters (4022) are connected with the other end of the track (401), the two limiters are fixed on two mutually parallel side walls of the convex bump (105), and the limiters are connected with the information input end of the controller (6).

7. The PVA alcoholysis system of claim 6, wherein, The trolley (403) comprises wheels (4031), an axle (4032) connected with the wheels (4031), and a frame plate (4033) arranged on the axle (4032), the wheels (4031) roll on the single track (4011), every two wheels (4031) form a group, the wheels (4031) in the same group are connected at two ends of the axle (4032), the axle (4032) is used for supporting the frame plate (4033), and the frame plate (4033) is provided with a through hole for fixing the gas cylinder (404).

8. The PVA alcoholysis system of claim 7, wherein, 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 with the cylinder barrel (4041), 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 tail end of the thermal resistance core rod (405) is a sharp head, the lower part of the thermal resistance core rod (405) is provided with fins (4051), the fins (4051) are symmetrically arranged on both sides of the thermal resistance core rod (405), the bottom edge of the fin (4051) forms a cutting edge (4052), the plane where the fin (4051) is located is perpendicular to the advancing direction of the reactant, the other end of the air source line is connected with the gas cylinder through the air source switch (408), the air source switch (408) and the electromagnetic valve (406) are connected with the controller (6), and the air source line and the power line are in a multi-turn spiral coiled state between the winding (407) and the air cylinder (404).

9. The PVA alcoholysis system of claim 1, wherein, The flushing assembly (5) comprises a plurality of spray heads (501) arranged below the belt (101), a liquid inlet pipe (502) for conveying flushing liquid, a liquid collecting cover (503) arranged around the spray head (501) and used for collecting flushing liquid, a liquid outlet pipe connected with the bottom end of the liquid collecting cover (503), the spray head (501) faces the back of the belt (101), a plurality of spray heads (501) are arranged side by side at equal intervals, the top of the spray head (501) is provided with a flat-shaped spray port (508), the long axis of the spray port (508) is perpendicular to the advancing direction of the belt (101), one end of the liquid inlet pipe (502) extends into the liquid collecting cover (503) and is connected with a liquid spraying main pipe (509), the liquid spraying main pipe (509) is divided into a plurality of upward extending branch pipes, the port of each branch pipe is connected with a spray head (501), the end of the liquid inlet pipe (502) away from the spray head (501) is connected with a waste liquid collecting tank, the liquid inlet pipe (502) is sequentially provided with a liquid pump (504), an adjusting valve (505) and a flow meter (506) along the conveying direction of the flushing liquid, the liquid pump (504) and the adjusting valve (505) are connected with the information output end of the controller (6), and the flow meter (506) is connected with the information input end of the controller (6).

10. The PVA alcoholysis system of claim 9, wherein, The liquid collecting cover (503) is an inverted cone with a large top and a small bottom, the top edge of the liquid collecting cover (503) surrounds the spray head (501), the top edge of the liquid collecting cover (503) is attached to the belt (101), the bottom end of the liquid collecting cover (503) forms a closing opening (507) and is connected with one end of the liquid outlet pipe, the liquid collecting cover (503) is provided with a through hole, and the through hole is used for the liquid inlet pipe (502) to enter the inside of the liquid collecting cover (503).

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