Device and method for removing free fatty acids from waste vegetable oil

Abstract

The invention discloses a device and a method for removing free fatty acids from waste vegetable oil, and belongs to the technical field of devices and methods for removing free fatty acids from waste vegetable oil. The device comprises a tank body, a heater and a control cabinet, and is characterized in that the tank body comprises a reaction layer and a separation layer, a waste vegetable oil inlet pipe is arranged at the left part of the reaction layer, an alkali solution inlet pipe is arranged at the right part of the reaction layer, a steam inlet pipe is arranged at the upper part of the reaction layer, a stirring device is arranged in the reaction layer, the stirring device comprises a shell, a connecting rod, a fixing rod and a stirring paddle, a rotating shaft is arranged in the shell, a group of moving blades are arranged on the rotating shaft, a group of fixing frames are arranged between the inner wall of the reaction layer and the shell, a steam exhaust pipe is arranged between the fixing frames on the left part of the shell, the right end of the steam exhaust pipe is arranged between the fixing frames and passes through the left part of the shell, a circuit box is arranged on the right side of the reaction layer, a water vapor exhaust pipe, a waste vegetable oil inlet pipe, an alkali solution inlet pipe, a soap solution exhaust pipe and a glycerin exhaust pipe are arranged in the circuit connection box in order from top to bottom, a solenoid valve 1 is arranged on the water vapor exhaust pipe, a control box is arranged at the bottom of the circuit connection box, a circuit line is connected with the control box, and a control panel is arranged on the control box.

Description

Technical Field

[0001] The invention relates to the technical field of removing free fatty acids from waste vegetable oil, in particular to a device and a method for removing free fatty acids from waste vegetable oil. Background Art

[0002] Vegetable oil refers to a compound composed of fatty acids and glycerol, which is widely distributed in nature. All fats extracted from plant seeds, pulp and other parts are collectively called vegetable oils. Vegetable oil is widely used in people's daily consumption.

[0003] The main source of discarded vegetable oil is the inedible vegetable oils produced by catering, food processing units and households, mainly including swill oil, frying waste oil, gutter oil and range hood condensate oil. Vegetable oil is oily and watery, and the higher the temperature, the more free fatty acids are produced, forming rancidity. The main chemical component of vegetable oil is triglycerides, which are hydrolyzed into glycerol (about 10%) and free fatty acids (90%). When frying, the temperature of vegetable oil rises to 180-200℃. High temperature is the main condition for the hydrolysis reaction of triglycerides.

[0004] Waste vegetable oil mainly contains triglycerides, free fatty acids and glycerol. Waste vegetable oil is no longer usable after frying, and if left outside for a long time it will become rancid and produce a pungent odor, seriously polluting the environment. The existing waste vegetable oil is generally directly landfilled in small quantities, while some large oil mills that process waste vegetable oil will collect and then centrally process it. The main purpose of the treatment is to react the free fatty acids in the waste vegetable oil with liquid alkali to produce fatty acid sodium, i.e. liquid soap, which is the main raw material for making soap. At the same time, liquid soap and glycerol are separated, and glycerol can be used to make skin care products.

[0005] In the prior art, when deacidifying waste vegetable oil, the processing steps used are relatively complicated, and more than a dozen reaction devices are required. Moreover, only free fatty acids in the waste vegetable oil can be removed, and triglycerides contained in the waste vegetable oil are mixed in glycerol and part of the sodium fatty acid, resulting in low purity of liquid soap and glycerol. In addition, in order to accelerate and fully react the free fatty acids and liquid alkali when the acid-base reaction occurs, a stirring device is required for stirring. Most of the existing stirring devices use a motor to drive the stirring rod. Since the storage capacity of the oil in the reaction tank of the oil plant is tens or even hundreds of tons, the motor driving the stirring rod needs to consume a lot of electricity. During stirring, as the reactants in the reaction tank increase, the resistance to the stirring rod increases, and the speed of the stirring rod decreases. In order to maintain the speed, the power consumption of the motor gradually increases. Moreover, the function of rotating the stirring rod faster and faster as the mixture increases cannot be achieved, resulting in the rate of the stirring reaction not being improved. After the sodium fatty acid and glycerol are separated, the glycerol still contains a large amount of water, and an additional step is required to separate the glycerol and the water, which increases the cost and reaction steps. Summary of the invention

[0006] In order to solve the technical problems mentioned in the above background technology, the present invention provides a device and method for removing free fatty acids from waste vegetable oil, and the technical scheme adopted is as follows:

[0007] The device for removing free fatty acids from waste vegetable oil comprises a tank body, a heater and a control cabinet, and is characterized in that: the tank body comprises a reaction layer and a separation layer, the reaction layer and the separation layer are fixedly connected, a waste vegetable oil inlet pipe is provided at the left part of the reaction layer, and the waste vegetable oil enters the reaction layer through the waste vegetable oil inlet pipe under high pressure conditions, a alkali liquid inlet pipe is provided at the right part of the reaction layer, and the alkali liquid enters the reaction layer through the alkali liquid inlet pipe under high pressure conditions, a steam inlet pipe is provided at the upper part of the reaction layer, and the steam generated by the heating reaction in the reaction layer enters the steam exhaust pipe through the steam inlet pipe, a stirring device is provided in the reaction layer, and the stirring device comprises a shell, a connecting rod, a fixing rod and a stirring paddle, and a heat insulating layer is provided on the inner wall of the shell to isolate the reaction layer The high temperature inside makes the temperature in the shell and the temperature in the reaction layer not interfere with each other. A rotating shaft is arranged in the shell, and the rotating shaft is a hollow structure. A group of moving blades are arranged on the rotating shaft. The steam heat energy in the steam exhaust pipe is converted into kinetic energy for the rotation of the moving blades, so that the moving blades drive the rotating shaft to rotate. A bearing 1 is arranged in the end of the shell, and the rotating shaft rotates in the bearing 1. At the same time, the rotating shaft limits the bearing. A steam inlet hole is arranged on the part of the rotating shaft between the bearing 1 and the moving blades. The steam that has done work in the shell enters the rotating shaft through the air inlet hole. Rotary joints are arranged on the upper and lower sides of the shell. The rotating shaft passes through the interior of the rotating joint and is fixedly connected to the rotating joint. Therefore, when the rotating shaft rotates, the rotating joint also rotates. Bearing 2 is provided on the inner walls of the upper and lower parts of the reaction layer. The bearing 2 is movably connected to the rotating shaft, and the rotating shaft rotates in the bearing 2. A connecting rod is provided on the rotating joint. The rotation of the rotating joint drives the connecting rod to rotate. The connecting rod is fixedly connected to the fixed rod. The rotation of the connecting rod drives the fixed rod to rotate. A group of stirring paddles is provided on the fixed rod. The rotation of the fixed rod drives the stirring paddle to rotate. A bearing 3 is provided on the shell. The bearing 3 includes an outer ring and an inner ring. The inner ring is provided in the outer ring. The inner ring is fixedly connected to the outer surface of the shell. The outer ring is fixedly connected to one end of the fixed rod. The rotation of the fixed rod drives the outer ring to rotate. A group of fixing frames are provided between the inner wall of the reaction layer and the shell. The fixing frames fix the shell. A steam exhaust pipe is provided in the shell, the right end of the steam exhaust pipe is provided between the fixing frames and passes through the left part of the shell, the left end of the steam exhaust pipe passes through the left part of the reaction layer and is connected to the steam inlet pipe, the heater comprises an electric heating pipe and a circuit box, the electric heating pipe is connected to the circuit box, the circuit in the circuit box provides power for the electric heating pipe, an electric heating pipe is provided between the fixing frames on the right part of the shell, the electric heating pipe heats the mixture in the reaction layer, a circuit box is provided on the right side of the reaction layer, a circuit line is provided at the bottom of the circuit box, the control cabinet controls the heater through the circuit line, a soap liquid exhaust pipe is provided at the bottom end of the right part of the reaction layer, only soap liquid is left after a series of reactions in the reaction layer, and the soap liquid is discharged through the soap liquid exhaust pipe;

[0008] A separation layer is provided at the bottom of the reaction layer, a water vapor discharge pipe is provided at the left part of the separation layer, and water vapor without glycerin is discharged through the water vapor discharge pipe. An interface is provided in the separation layer, and the interface is bucket-shaped. The interface is connected with the second bearing. Glycerin and water vapor enter the interface from the inside of the rotating shaft through the inside of the second bearing, and then enter the steam separation cover from the interface. A steam separation cover is provided at the bottom of the interface, and steam separation holes are provided on the bottom surface of the steam separation cover. Glycerin and water vapor in the steam separation cover are discharged through the steam separation air and enter the separation layer. The steam separation cover and the steam separation holes make the steam fall evenly to prevent it from rushing directly into the separation layer under the action of pressure, so that the water vapor will carry part of glycerin and be discharged from the water vapor discharge pipe. A glycerin discharge pipe is provided at the bottom end of the right part of the separation layer, and the glycerin separated from the separation layer is discharged through the glycerin discharge pipe.

[0009] The control cabinet comprises a circuit connection box and a control box. The circuit connection box is provided with a water vapor exhaust pipe, a waste vegetable oil inlet pipe, an alkali solution inlet pipe, a soap solution exhaust pipe and a glycerol exhaust pipe from top to bottom. The water vapor exhaust pipe is provided with a solenoid valve 1, which controls the opening and closing of the water vapor exhaust pipe. The waste vegetable oil inlet pipe is provided with a solenoid valve 2, which controls the opening and closing of the waste vegetable oil. The alkali solution inlet pipe is provided with a solenoid valve 3, which controls the opening and closing of the alkali solution inlet pipe. The soap solution exhaust pipe is provided with a solenoid valve 4, which controls the opening and closing of the soap solution exhaust pipe. The glycerol exhaust pipe is provided with a solenoid valve 5, which controls the opening or closing of the glycerol exhaust pipe. The circuit in the circuit connection box is connected with the solenoid valve 1, the solenoid valve 2, the solenoid valve 3, the solenoid valve 4 and the solenoid valve 5. The bottom of the circuit connection box is provided with a control box. The circuit line is connected with the control box to control the opening and closing of the heater. The control box is provided with a control panel to control the operation of the circuit system of the control tube.

[0010] Preferably: the circuit connection box is provided with a box door to protect the circuit of the circuit connection box.

[0011] A method for removing free fatty acids from waste vegetable oil using the device for removing free fatty acids from waste vegetable oil according to claim 1, characterized in that it specifically comprises the following steps:

[0012] S1: Open solenoid valve 2 through the control box to allow the waste vegetable oil to enter the reaction layer through the waste vegetable oil inlet pipe under high pressure, open solenoid valve 3 to allow the alkali solution to enter the reaction layer through the alkali solution inlet pipe under high pressure, start the heater through the control box and adjust the heating temperature of the heater within the range of 290-359.4℃, set the heating time to 8 hours, and when 8 hours has passed, when the mixed liquid in the reaction layer reaches two-thirds of the volume of the reaction layer, close solenoid valve 2 and solenoid valve 3 at the same time to stop transporting waste vegetable oil and alkali solution into the reaction layer.

[0013] Waste vegetable oil is composed of triglycerides, free fatty acids and glycerol.

[0014] When the mixture in the reaction layer is heated to 290-359.4℃, the triglyceride is hydrolyzed into free fatty acids and glycerol in the 180-200℃ range, and mixed with the original free fatty acids and glycerol in the waste vegetable oil, so that only free fatty acids and glycerol are left in the reaction layer. At the same time, the water in the liquid alkali in the reaction layer is heated and evaporated to form water vapor, which enters the steam inlet pipe, and then enters the steam exhaust pipe until it enters the shell. The thermal energy of the steam is converted into kinetic energy for the rotation of the moving blades, so that the moving blades rotate, and the shaft rotates, so that the stirring paddle also rotates, and the free fatty acids and alkali solution are fully stirred, so that the free fatty acids and the liquid alkali react fully, and the free fatty acids react with the alkali solution to generate sodium fatty acids and water. At the same time, as the waste vegetable oil and alkali solution in the reaction layer continue to increase, more and more steam is generated. At the same time, because the heater continuously increases the heating temperature, the greater the steam pressure, the more violent the molecular movement, and the faster the steam speed, the faster the rotor rotates, achieving the effect that the more mixed liquid in the reaction layer, the faster the stirring rod speed, and the situation that the more mixed liquid in the reaction layer, the greater the resistance, resulting in a slower speed will not occur.

[0015] Synchronously, when the temperature in the reaction layer reaches the set range of 290-359.4, since the boiling point of glycerol is 290℃ and the boiling point of sodium fatty acid is 359.4℃, glycerol also evaporates into gaseous state, mixes with water vapor, enters the steam exhaust pipe through the steam inlet pipe, and then enters the shell, further enhancing the steam energy, so that the rotation speed is further continuously increased. Since the gaseous glycerol and water vapor are continuously discharged from the reaction layer, only sodium fatty acid, i.e. soap solution, is left in the reaction layer. As the steam in the reaction layer is continuously discharged, the steam energy in the shell disappears, and the moving blades and rotors no longer rotate.

[0016] S2: After step S1, after another 4 hours, the separation of soap liquid and glycerin is completed, the solenoid valve 4 is opened, the soap liquid is discharged from the soap liquid discharge pipe, and the soap liquid is pumped into the soap liquid storage tank by the corresponding liquid pump for storage.

[0017] S3: Open solenoid valve 1 at the same time as step S1, and the water vapor without glycerin is discharged through the water vapor exhaust pipe, and the water vapor without glycerin is pumped into the condenser by the corresponding steam pump for storage.

[0018] S4: At the same time as step S1, the electromagnetic valve 5 is opened, and the glycerin is discharged through the glycerin discharge pipe. The glycerin is pumped into the glycerin storage tank by the corresponding liquid pump for storage.

[0019] The present invention has the following advantages:

[0020] By heating the mixture in the reaction layer to 290-359.4°C through the heater, the hydrolysis reaction of triglycerides in the waste vegetable oil is achieved when the heating section reaches 180-200°C, and the produced free fatty acids and glycerol are mixed with the free fatty acids and glycerol in the original waste vegetable oil, solving the problem of inability to eliminate the triglycerides mixed in the waste vegetable oil. The distillation and separation of soap solution and glycerol produced by the simultaneous neutralization reaction of free fatty acids and alkali solution when the temperature reaches 290-359.4°C is also achieved, and three reactions are achieved in one set of processes.

[0021] While realizing the hydrolysis reaction of triglyceride and the neutralization reaction of free fatty acid and alkali solution, part of the water in the alkali solution is evaporated at high temperature to form water vapor to provide kinetic energy for the moving blades, so that the rotating shaft rotates to drive the stirring paddle to provide stirring for the neutralization reaction of free fatty acid and alkali solution, so that the reaction is sufficient, avoiding the use of the motor to consume a large amount of electric energy to drive the stirring rod to rotate and stir.

[0022] As waste vegetable oil and alkali solution continue to enter the reaction layer and the stirring resistance continues to increase, when it reaches 290-359.4℃, glycerin also evaporates and turns into vapor, mixing with water vapor to provide more and more steam energy for the steam, making the steam pressure greater, the molecular movement more violent, the steam speed faster, and therefore the faster the rotor rotates, achieving the effect of faster stirring rod speed as the more mixed liquid in the reaction layer, instead of slower speed due to greater resistance caused by more mixed liquid in the reaction layer.

[0023] After the water vapor and glycerin vapor in the shell have completed their work, their heat energy loss is 30%-35%. Therefore, the temperature of glycerin and water vapor discharged from the shell into the separation layer is 233-251°C. The boiling point of glycerin is 290°C, and the boiling point of water is 100°C. Therefore, the glycerin becomes liquid in the separation layer and remains in the separation layer, while the water is still steam and is discharged through the steam exhaust pipe. The steam energy in the shell that provides power to the stirring paddle completes the work and realizes the separation of water vapor and glycerin in the separation layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of the present invention;

[0025] Figure 2 This is an appearance diagram of the present invention;

[0026] Figure 3 A top view of the tank body of the present invention;

[0027] Figure 4 It is a structural diagram of the stirring device of the present invention;

[0028] Figure 5 For the present invention Figure 4 A local enlarged view of point b;

[0029] Figure 6 This is an appearance diagram of the stirring device of the present invention;

[0030] Figure 7 A top view of the stirring device of the present invention;

[0031] Figure 8 For the present invention Figure 1 A local enlarged view of point a;

[0032] Fig. 9 A bottom view of the steam distribution hood of the present invention;

[0033] Fig.10 is a structural diagram of a heater of the present invention;

[0034] Fig.11 For the present invention Fig.10 A local enlarged view of point c;

[0035] Fig.12 A top view of the fixing frame of the present invention;

[0036] Fig.13 It is the structural diagram of the control cabinet of the present invention.

[0037] Figures: 1 tank body, 2 heater, 3 control cabinet, 4 reaction layer, 5 separation layer, 6 waste vegetable oil inlet pipe, 7 alkali solution inlet pipe, 8 steam inlet pipe, 9 shell, 10 connecting rod, 11 fixed rod, 12 stirring paddle, 13 rotating shaft, 14 moving blade, 15 bearing one, 16 steam inlet hole, 17 rotary joint, 18 bearing two, 19 bearing three, 20 outer ring, 21 inner ring, 22 fixed frame, 23 steam exhaust pipe, 24 electric heating pipe, 25 circuit box, 26 circuit line, 27 soap liquid exhaust pipe, 28 water vapor exhaust pipe, 29 interface, 30 steam hood, 31 steam hole, 32 glycerin exhaust pipe, 33 circuit connection box, 34 control box, 35 solenoid valve one, 36 solenoid valve two, 37 solenoid valve three, 38 solenoid valve four, 39 solenoid valve five, 40 control panel, 41 box door, 42 insulation layer. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0039] like Figure 1-Figure 13 As shown:

[0040] The device for removing free fatty acids from waste vegetable oil comprises a tank body 1, a heater 2 and a control cabinet 3, and is characterized in that: the tank body 1 comprises a reaction layer 4 and a separation layer 5, the left part of the reaction layer 4 is provided with a waste vegetable oil inlet pipe 6, the right part of the reaction layer 4 is provided with an alkali solution inlet pipe 7, the upper part of the reaction layer 4 is provided with a steam inlet pipe 8, the reaction layer 4 is provided with a stirring device, the stirring device comprises a shell 9, a connecting rod 10, a fixing rod 11 and a stirring paddle 12, the inner wall of the shell 9 is provided with a heat insulation layer 42, and the shell 9 is provided with a There is a rotating shaft 13, the rotating shaft 13 is a hollow structure, a group of moving blades 14 are arranged on the rotating shaft 13, a bearing 15 is arranged in the end of the shell 9, the rotating shaft 13 is provided with a steam inlet hole 16 on the part between the bearing 15 and the moving blades 14, the upper and lower sides of the shell 9 are provided with a rotating joint 17, the rotating shaft 13 passes through the rotating joint 17 and is fixedly connected to the rotating joint 17, the inner walls of the upper and lower parts of the reaction layer 4 are both provided with bearings 18, the bearings 18 are movably connected to the rotating shaft 13, the A connecting rod 10 is provided on the rotary joint 17, and the connecting rod 10 is fixedly connected to the fixed rod 11, and a group of stirring paddles 12 are provided on the fixed rod 11. A bearing 3 19 is provided on the shell 9, and the bearing 3 19 includes an outer ring 20 and an inner ring 21. The outer ring 20 is provided with an inner ring 21, and the inner ring 21 is fixedly connected to the outer surface of the shell 9, and the outer ring 20 is fixedly connected to one end of the fixed rod 11. A group of fixing frames 22 are provided between the inner wall of the reaction layer 4 and the shell 9, and a steam exhaust pipe 2 is provided in the shell 9. 3. The right end of the steam exhaust pipe 23 is arranged between the fixing frames 22 and passes through the left part of the shell 9. The left end of the steam exhaust pipe 23 passes through the left part of the reaction layer 4 and is connected to the steam inlet pipe 8. The heater 2 includes an electric heating pipe 24 and a circuit box 25. The electric heating pipe 24 is connected to the circuit box 25. The electric heating pipe 24 is arranged between the fixing frames 22 on the right part of the shell 9. The circuit box 25 is arranged on the right side of the reaction layer 4. The circuit line 26 is arranged at the bottom of the circuit box 25. The bottom end of the right part of the reaction layer 4 is provided with a soap liquid exhaust pipe 27;

[0041] A separation layer 5 is provided at the bottom of the reaction layer 4, a water vapor discharge pipe 28 is provided at the left part of the separation layer 5, an interface 29 is provided inside the separation layer 5, the interface 29 is bucket-shaped, the interface 29 is connected to the bearing 2 18, a steam separation cover 30 is provided at the bottom of the interface 29, a steam separation hole 31 is provided on the bottom surface of the steam separation cover 30, and a glycerin discharge pipe 32 is provided at the bottom end of the right part of the separation layer 5;

[0042] The control cabinet 3 includes a circuit connection box 33 and a control box 34. The circuit connection box 33 is provided with a water vapor exhaust pipe 28, a waste vegetable oil inlet pipe 6, an alkali solution inlet pipe 7, a soap liquid exhaust pipe 27 and a glycerol exhaust pipe 32 from top to bottom. The water vapor exhaust pipe 28 is provided with a solenoid valve 1 35, the waste vegetable oil inlet pipe 6 is provided with a solenoid valve 2 36, the alkali solution inlet pipe 7 is provided with a solenoid valve 37, the soap liquid exhaust pipe 27 is provided with a solenoid valve 4 38, the glycerol exhaust pipe 32 is provided with a solenoid valve 5 39, the circuit connection box 33 is provided with a control box 34 at the bottom, the circuit line 26 is connected to the control box 34, the control box 34 is provided with a control panel 40, and the circuit connection box 33 is provided with a box door 41.

[0043] The method for removing free fatty acids from waste vegetable oil is characterized by comprising the following steps:

[0044] S1: Open the solenoid valve 262 through the control box, so that the waste vegetable oil enters the reaction layer through the waste vegetable oil inlet pipe 6 under high pressure, open the solenoid valve 37, so that the alkali solution enters the reaction layer 4 through the alkali solution inlet pipe 7 under high pressure, start the heater 2 through the control box 34 and adjust the heating temperature of the heater 2 within the range of 290-359.4°C, set the heating time to 8 hours, and when 8 hours has passed, when the mixed liquid in the reaction layer 4 reaches two-thirds of the volume of the reaction layer, close the solenoid valve 2 36 and the solenoid valve 3 37 at the same time, and stop transporting the waste vegetable oil and alkali solution into the reaction layer 4.

[0045] S2: After step S1, after 4 hours of separation of the soap liquid and glycerin, the solenoid valve 38 is opened and the soap liquid discharge pipe 27 discharges the soap liquid.

[0046] S3: At the same time as step S1, the solenoid valve 35 is opened, and the water vapor without glycerin is discharged through the water vapor exhaust pipe 28.

[0047] S4: At the same time as step S1, the electromagnetic valve 5 39 is opened, and the glycerin is discharged through the glycerin discharge pipe 32.

[0048] The present invention is simple to operate, convenient to use, and suitable for comprehensive promotion and application. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for removing free fatty acids from waste vegetable oil, comprising a tank (1), a heater (2) and a control cabinet (3), characterized in that: The tank body (1) comprises a reaction layer (4) and a separation layer (5). The left part of the reaction layer (4) is provided with a waste vegetable oil inlet pipe (6). The waste vegetable oil entering the reaction layer (4) reaches the 180-200°C range and triglycerides are hydrolyzed into free fatty acids and glycerol. The right part of the reaction layer (4) is provided with an alkali solution inlet pipe (7). The upper part of the reaction layer (4) is provided with a steam inlet pipe (8). The reaction layer (4) is provided with a stirring device. The stirring device comprises a shell (9), a connecting rod (10), a fixing rod (11) and a stirring paddle (12). The inner wall of the shell (9) is provided with a heat insulating layer (42). The shell (9) is provided with a rotating The rotating shaft (13) is a hollow structure, a group of moving blades (14) are arranged on the rotating shaft (13), a bearing (15) is arranged in the end of the shell (9), a steam inlet hole (16) is arranged on the rotating shaft (13) between the bearing (15) and the moving blades (14), a rotating joint (17) is arranged on the upper and lower sides of the shell (9), the rotating shaft (13) passes through the rotating joint (17) and is fixedly connected to the rotating joint (17), the inner walls of the upper and lower parts of the reaction layer (4) are both provided with bearings (18), the bearings (18) are movably connected to the rotating shaft (13), and the rotating joint A connecting rod (10) is provided on the shell (17), the connecting rod (10) is fixedly connected to the fixing rod (11), the fixing rod (11) is provided with a group of stirring paddles (12), the shell (9) is provided with a bearing three (19), the bearing three (19) comprises an outer ring (20) and an inner ring (21), the outer ring (20) is provided with an inner ring (21), the inner ring (21) is fixedly connected to the outer surface of the shell (9), the outer ring (20) is fixedly connected to one end of the fixing rod (11), a group of fixing frames (22) are provided between the inner wall of the reaction layer (4) and the shell (9), and a steam exhaust pipe (23) is provided in the shell (9). ), the right end of the steam exhaust pipe (23) is arranged between the fixing frames (22) and passes through the left part of the shell (9), the left end of the steam exhaust pipe (23) passes through the left part of the reaction layer (4) and is connected to the steam inlet pipe (8), the heater (2) comprises an electric heating pipe (24) and a circuit box (25), the electric heating pipe (24) is connected to the circuit box (25), the electric heating pipe (24) is arranged between the fixing frames (22) on the right part of the shell (9), the circuit box (25) is arranged on the right side of the reaction layer (4), the bottom of the circuit box (25) is provided with a circuit line (26), and the bottom end of the right part of the reaction layer (4) is provided with a soap liquid exhaust pipe (27); A separation layer (5) is provided at the bottom of the reaction layer (4), a water vapor discharge pipe (28) is provided at the left portion of the separation layer (5), an interface (29) is provided inside the separation layer (5), the interface (29) is bucket-shaped, the interface (29) is connected to the second bearing (18), a steam separation cover (30) is provided at the bottom of the interface (29), a steam separation hole (31) is provided on the bottom surface of the steam separation cover (30), and a glycerin discharge pipe (32) is provided at the bottom end of the right portion of the separation layer (5); The control cabinet (3) comprises a circuit connection box (33) and a control box (34). The circuit connection box (33) is provided with a water vapor exhaust pipe (28), a waste vegetable oil inlet pipe (6), an alkali solution inlet pipe (7), a soap solution exhaust pipe (27) and a glycerol exhaust pipe (32) in order from top to bottom. The water vapor exhaust pipe (28) is provided with a first solenoid valve (35). The waste vegetable oil inlet pipe (6) is provided with a second solenoid valve (36). The alkali solution inlet pipe (7) is provided with a third solenoid valve (37). The soap solution exhaust pipe (27) is provided with a fourth solenoid valve (38). The glycerol exhaust pipe (32) is provided with a fifth solenoid valve (39). The circuit connection box (33) is provided with a control box (34) at the bottom. The circuit line (26) is connected to the control box (34). The control box (34) is provided with a control panel (40). The temperature of the glycerin and water vapor discharged into the separation layer (5) in the shell (9) is 233-251°C, the boiling point of glycerin is 290°C, and the heater (2) is started through the control box (34) and the heating temperature of the heater (2) is adjusted within the range of 290-359.4°C.

2. The device for removing free fatty acids from waste vegetable oil according to claim 1, characterized in that: The circuit connection box (33) is provided with a box door (41).

3. A method for removing free fatty acids from waste vegetable oil using the device for removing free fatty acids from waste vegetable oil according to claim 1, characterized in that: The specific steps include: S1: Opening the second solenoid valve (26) through the control box, so that the waste vegetable oil enters the reaction layer through the waste vegetable oil inlet pipe (6) under high pressure, opening the third solenoid valve (37), so that the alkali solution enters the reaction layer (4) through the alkali solution inlet pipe (7) under high pressure, and hydrolyzing the triglyceride into free fatty acids and glycerol at a temperature of 180-200° C., starting the heater (2) through the control box (34) and adjusting the heating temperature of the heater (2) within the range of 290-359.4° C., setting the heating time to 8 hours, and when the mixed liquid in the reaction layer (4) reaches two-thirds of the volume of the reaction layer after 8 hours, closing the second solenoid valve (36) and the third solenoid valve (37) at the same time, and stopping the delivery of the waste vegetable oil and alkali solution into the reaction layer (4); S2: After step S1, after 4 hours of separation of soap liquid and glycerin, the solenoid valve 4 (38) is opened and the soap liquid is discharged through the soap liquid discharge pipe (27); S3: Open the solenoid valve 1 (35) at the same time as step S1, and the water vapor without glycerin is discharged through the water vapor exhaust pipe (28); S4: At the same time as step S1, the electromagnetic valve 5 (39) is opened, and the glycerin is discharged through the glycerin discharge pipe (32).

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