Method and device for preparing biodiesel through non-catalytic alcoholysis
The non-catalytic alcoholysis method addresses catalyst-related issues in biodiesel production by using a rotating mixer device to achieve efficient, safe, and uniform mixing of methanol with waste oils, resulting in high yields of fatty acid methyl esters and glycerol.
Patent Information
- Application Number
- CN202411441386.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-15
- Publication Date
- 2025-01-03
AI Technical Summary
Existing biodiesel production methods using chemical and bio-enzyme catalysis face issues with catalyst corrosion, slow reaction rates, and uneven mixing of methanol with waste oils, posing safety risks and inefficiencies.
A non-catalytic alcoholysis method at medium-high temperature and pressure, using a device with rotating mixers to evenly combine methanol and waste oils, eliminating the need for catalysts and ensuring thorough mixing.
The method achieves high yields of fatty acid methyl esters and glycerol with improved safety and efficiency by avoiding catalysts and ensuring uniform mixing, while reducing equipment corrosion and operational hazards.
Smart Images
Figure CN119242385A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of biodiesel preparation, and in particular relates to a method for preparing biodiesel by non-catalytic alcoholysis and a device thereof. Background Art
[0002] Biodiesel is a mixture of triglycerides and methanol from various waste animal and plant oils, which undergo an ester exchange reaction under the action of a catalyst to produce fatty acid methyl esters and low-concentration glycerol. Common production methods include chemical catalysis, bio-enzyme catalysis and supercritical method. The chemical catalysis method mainly involves an ester exchange reaction between fatty acid triglycerides and low-molecular alcohols under the action of a chemical acid catalyst or an alkaline catalyst to produce fatty acid methyl esters and glycerol. Chemical catalysis methods are mainly divided into homogeneous catalysis and heterogeneous catalysis. The catalysts used for esterification reactions in homogeneous catalysis are mainly strong acids and strong bases. Acid catalysts include sulfuric acid, hydrochloric acid and benzenesulfonic acid, and base catalysts include sodium methoxide, potassium hydroxide, sodium hydroxide, potassium carbonate and organic bases. The above catalysts are highly corrosive to equipment and have a small scope of application. The heterogeneous catalysis method uses solid acid and solid base catalysts, but the reaction rate is too slow and the reaction time is long. Strong acids and strong bases are highly corrosive to the reaction device, and construction workers are also at high risk during the construction process. Moreover, methanol is a volatile gas. In an environment above the vaporization temperature of methanol, it is easy to volatilize, and it is easy to fail to mix evenly with waste animal and plant oils and fats. During the addition of methanol, the high temperature environment will quickly vaporize, and it is impossible to ensure full contact and uniform mixing with the waste animal and plant oils and fats. Therefore, the existing technology needs further improvement. Summary of the invention
[0003] The object of the present invention is to provide a method for preparing biodiesel at medium-high temperature, medium-high pressure and without using a catalyst, and a device thereof which can evenly mix methanol and waste animal and plant oils.
[0004] Based on the above purpose, the present invention adopts the following technical solutions:
[0005] A method for preparing biodiesel by non-catalytic alcoholysis comprises the following steps: (1) mixing waste animal and plant fats and oils with methanol and stirring the mixture at 185°C-200°C and 1.5MPa-2.0MPa for 5-6h, wherein the fatty acids in the waste animal and plant fats and oils react with the methanol to generate fatty acid methyl esters and water;
[0006] Among them, the chemical reaction between fatty acids and methanol is R-COOH+CH3OH→R-COOH3+H2O;
[0007] (2) hydrolyzing part of the triglycerides in the waste animal and vegetable oils and fats in step (1) with the water in step (1) at 185° C.-200° C. and 1.5 MPa-1.6 MPa, and subjecting the remaining triglycerides to an ester exchange reaction.
[0008] Among them, triglycerides and water undergo hydrolysis reaction, C3H5(OOCR)3+H2O→R-COOH+C3H8O3;
[0009] Triglycerides undergo ester exchange reaction: (RCOO)3C3H5+3CH3OH→3RCOOCH3+C3H5(OH)3.
[0010] Furthermore, the molar ratio of the waste animal and plant oils to the alcohol-oil in methanol is 5:1.
[0011] Furthermore, the mass of the triglyceride fraction that undergoes hydrolysis in step (2) accounts for 1-3% of the total triglyceride mass.
[0012] Furthermore, the fatty acid content of the waste animal and plant oils and fats is 30-60% of the total mass, and the triglyceride content of the waste animal and plant oils and fats is 40-70%.
[0013] A device for preparing biodiesel by using non-catalytic alcoholysis comprises a high-pressure tank, a first feed port, a second feed port and a vacuum port are arranged on the high-pressure tank, the second feed port is connected to a feed pipe, the feed pipe is connected to a first infusion cavity through a first bearing, a first gear is arranged outside the first infusion cavity, a first motor is arranged inside the high-pressure tank, a first motor base is connected to a top wall of the high-pressure tank, an output end of the first motor is connected to a second gear, the first gear and the second gear are meshed with each other to form a structure in which the first gear can rotate synchronously with the second gear, the lower end surface of the first infusion cavity is connected to a first liquid guide tube, and a second bearing is arranged outside the first liquid guide tube The second infusion cavity is connected through the second bearing, a third gear is arranged outside the second infusion cavity, a second motor is arranged at the bottom of the first infusion cavity, a second motor base is connected to the lower end surface of the first infusion cavity, an output end of the second motor is connected to the fourth gear, the third gear and the fourth gear are meshed with each other to form a structure in which the third gear and the fourth gear rotate synchronously, the second infusion cavity is connected to the rotating box through several second liquid guide tubes, heating columns are evenly distributed in the rotating box, several cutting holes are arranged on the rotating box, liquid permeable holes are evenly distributed on the side walls of the cutting holes, a metal cutting net is arranged in the circular axis surface of the cutting hole, and several heaters are arranged in the high-pressure tank.
[0014] Furthermore, the rotating box is a rectangular box, one end of the second liquid guide tube is connected to the upper end of the rotating box in the width direction, and the other end of the second liquid guide tube is connected to the lower end surface of the second infusion cavity. The cutting hole passes through the largest rectangular surface on the rotating box. The cutting hole is made by the first cylinder passing through the rotating box, and the circular edges of the first cylinder are respectively sealed and connected to the two largest rectangular surfaces of the rotating box.
[0015] Furthermore, the first infusion cavity includes a first hollow cylinder, the upper end of the first cylinder is connected through the second cylinder, the first bearing is located between the outer wall of the feed tube and the inner wall of the second cylinder, and the first gear is sleeved on the outer wall of the second cylinder.
[0016] Furthermore, the second infusion cavity includes a second hollow cylinder, the upper end of the second cylinder is connected through the third cylinder, the second bearing is located between the outer wall of the first catheter and the inner wall of the third cylinder, and the second gear is sleeved on the outer wall of the third cylinder.
[0017] Furthermore, the heating column shell is made of heat-conducting metal, a heater heating end is arranged in the heating column shell, a line protection box is arranged on the outside of the rotating box, the line protection box is filled with thermal insulation cotton, the heater line end and the line are located in the line protection box and are wrapped with thermal insulation cotton, the line protection box is connected to the battery placement box, the battery placement box is filled with thermal insulation cotton, and a manhole is arranged on the high-pressure tank.
[0018] The present invention generates high content of fatty acid methyl ester under medium-high temperature and medium-high pressure without adding any strong acid or strong base catalyst, and can also convert triglyceride in waste animal and plant oils into glycerol, and the generated glycerol byproduct has high content. In addition, the device provided in combination with the method for preparing biodiesel by catalytic alcoholysis of the present invention uses a first motor and a second motor to respectively drive the first infusion cavity and the second infusion cavity to rotate, and the first infusion cavity and the second infusion cavity drive the rotating box to rotate, and the rotating box can rotate in the entire high-pressure tank, and the heating column heats the rotating box by heating the rotating box, and the waste animal and plant oils are heated by the rotating box, and methanol directly enters from the pipeline, is heated by the heating column, and then flows out through the liquid permeable hole, and is mixed and reacted with the waste animal and plant oils during the rotation process, so that the methanol can be fully mixed with the waste animal and plant oils at the bottom, and a line protection box is provided at the same time to reduce the damage of high temperature and high pressure and chemical substances to the line. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a structural schematic diagram of the present invention;
[0020] Figure 2 It is a schematic diagram of the structure of the feeding tube and the first infusion cavity;
[0021] Figure 3 is a position relationship diagram of the third gear and the fourth gear;
[0022] Figure 4 It is the position relationship diagram of the rotating box and the heating column;
[0023] Figure 5 It is the position relationship diagram of the battery placement box and the rotating box;
[0024] Figure 6 It is a schematic diagram of the structure of cutting holes;
[0025] Figure 7 It is a schematic diagram of the structure of the second infusion cavity. DETAILED DESCRIPTION
[0026] Embodiment 1:
[0027] A method for preparing biodiesel by non-catalytic alcoholysis comprises the following steps: (1) mixing qualified palmitic acid oil raw material (water impurity <3%) with methanol, stirring and reacting at 185° C. and 1.5 MPa for 5 hours, wherein fatty acids in waste animal and plant oils and fats react with methanol to generate fatty acid methyl esters and water; the molar ratio of the qualified palmitic acid oil raw material (water impurity <3%) to the alcohol-oil in the methanol is 5:1.
[0028] Among them, the chemical reaction between fatty acids and methanol is R-COOH+CH3OH→R-COOH3+H2O;
[0029] The fatty acid mass in the waste animal and plant oils and fats accounts for 60% of the total mass, and the triglyceride content in the waste animal and plant oils and fats is 40%.
[0030] The mass of fatty acid methyl ester obtained after the fatty acid and methanol react is 99% of the total mass of fatty acid, and the conversion rate reaches 99%.
[0031] (2) hydrolyzing part of the triglycerides in the waste animal and vegetable oils and fats in step (1) with the water in step (1) at 185° C. and 1.5 MPa, and subjecting the remaining triglycerides to an ester exchange reaction.
[0032] Among them, triglycerides and water undergo hydrolysis reaction, C3H5(OOCR)3+H2O→R-COOH+C3H8O3;
[0033] Triglycerides undergo transesterification reaction: (RCOO)3C3H5+3CH3OH→3RCOOCH3+C3H5(OH)3.
[0034] The mass of the triglyceride that undergoes hydrolysis reaction in step (2) accounts for 1% of the total mass of triglycerides, the glycerol obtained after the triglyceride and water react has a conversion rate of 1%, and the remaining triglycerides undergo ester exchange reaction.
[0035] A device for preparing biodiesel by using non-catalytic alcoholysis comprises a high-pressure tank 1, a first feed port 2, a second feed port 3 and a vacuum port 4 are arranged on the high-pressure tank 1, the second feed port 3 is connected to a feed pipe 5, the feed pipe 5 is connected to a first infusion cavity 7 through a first bearing 6, a first gear 8 is arranged outside the first infusion cavity 7, a first motor 9 is arranged inside the high-pressure tank 1, a base of the first motor 9 is connected to a top wall of the high-pressure tank 1, an output end of the first motor 9 is connected to a second gear 10, the first gear 8 and the second gear 10 are meshed with each other, forming a structure in which the first gear 8 can rotate synchronously with the second gear 10, the lower end surface of the first infusion cavity 7 is connected to a first liquid guide tube 11, a second bearing 12 is arranged outside the first liquid guide tube 11 and is connected to a second infusion cavity 13 through the second bearing 12 A third gear 14 is disposed outside the second infusion cavity 13, a second motor 15 is disposed at the bottom of the first infusion cavity 7, a base of the second motor 15 is connected to the lower end surface of the first infusion cavity 7, an output end of the second motor 15 is connected to a fourth gear 16, the third gear 14 and the fourth gear 16 are meshed with each other, forming a structure in which the third gear 14 and the fourth gear 16 rotate synchronously, the second infusion cavity 13 is connected to a rotating box 18 through a plurality of second liquid guide tubes 17, heating columns 19 are evenly distributed in the rotating box 18, a plurality of cutting holes 20 are disposed on the rotating box 18, liquid permeable holes are evenly distributed on the side walls of the cutting holes 20, a metal cutting mesh 21 is disposed in the circular axis surface of the cutting hole 20, and the metal cutting mesh 21 is formed by metal blades intersecting each other, and a plurality of heaters 22 are disposed in the high-pressure tank 1. The rotating box 18 is a rectangular box, one end of the second liquid guide tube 17 is connected to the upper end of the rotating box 18 in the width direction, and the other end of the second liquid guide tube 17 is connected to the lower end surface of the second infusion cavity 13. The cutting hole 20 passes through the largest rectangular surface on the rotating box 18. The cutting hole 20 is made by the first cylinder 2001 passing through the rotating box 18, and the circular edges of the first cylinder 2001 are sealed and connected to the two largest rectangular surfaces of the rotating box 18 respectively.
[0036] The first infusion cavity 7 comprises a first hollow cylinder 701, the upper end of the first cylinder 701 is connected through the second cylinder 702, the first bearing 6 is located between the outer wall of the feeding tube 5 and the inner wall of the second cylinder 702, and the first gear 8 is sleeved on the outer wall of the second cylinder 702. The second infusion cavity 13 comprises a second hollow cylinder 1301, the upper end of the second cylinder 1301 is connected through the third cylinder 1302, the second bearing 12 is located between the outer wall of the first liquid guide tube 11 and the inner wall of the third cylinder 1302, and the second gear 10 is sleeved on the outer wall of the third cylinder 1302. The shell of the heating column 19 is made of heat-conducting metal, and a heater heating end is arranged in the shell of the heating column 19. A line protection box 23 is arranged on the outside of the rotating box 18, and the line protection box 23 is filled with insulation cotton. The heater line end and the line are located in the line protection box 23 and are wrapped with insulation cotton. The line protection box is connected to the battery placement box 24, and the battery placement box 24 is filled with insulation cotton. A manhole is arranged on the high-pressure tank 1.
[0037] When in use, open the first feed port 2 to add waste animal and plant fats into the first feed port 2, open the second feed port 3 to pass methanol, methanol enters the first infusion chamber 7, the methanol in the first infusion chamber 7 continues to flow from the first catheter 11 into the second infusion chamber 13, and then from the second infusion chamber 13 through the second catheter 17 into the rotating box 18, and then flows out through the liquid permeable hole on the rotating box 18. At the same time, the rotation of the first motor 9 and the second motor 15 can drive the rotating box 18 to rotate evenly, and the cutting net on the cutting hole cuts the impurities in the waste animal and plant fats, and mixes the methanol and the waste animal and plant fats evenly. The heater heats the rotating box 18 through the heating column 19, thereby heating the waste animal and plant fats comprehensively as it rotates, and mixing the heated methanol with the waste animal fats. If the device needs to be repaired or charged, it can be charged and repaired from the manhole after cleaning. Other methods can also be used to charge the motor and battery of the device.
[0038] Embodiment 2:
[0039] A method for preparing biodiesel by non-catalytic alcoholysis comprises the following steps: (1) mixing qualified soybean oil raw material (water impurity <3%) with methanol and reacting at 190° C. and 1.8 MPa with stirring for 5.5 h, wherein fatty acids in waste animal and plant oils and fats react with methanol to generate fatty acid methyl esters and water;
[0040] Among them, the chemical reaction between fatty acids and methanol is R-COOH+CH3OH→R-COOH3+H2O;
[0041] The fatty acid mass in the waste animal and plant oils and fats accounts for 50% of the total mass, and the triglyceride content in the waste animal and plant oils and fats is 50%.
[0042] The mass of fatty acid methyl ester obtained after the fatty acid and methanol react is 98% of the total mass of fatty acid, and the conversion rate reaches 98%.
[0043] (2) hydrolyzing part of the triglycerides in the waste animal and vegetable oils and fats in step (1) with the water in step (1) at 190° C. and 1.55 MPa, and subjecting the remaining triglycerides to an ester exchange reaction.
[0044] Among them, triglycerides and water undergo hydrolysis reaction, C3H5(OOCR)3+H2O→R-COOH+C3H8O3;
[0045] Triglycerides undergo transesterification reaction: (RCOO)3C3H5+3CH3OH→3RCOOCH3+C3H5(OH)3.
[0046] The mass of the triglyceride that undergoes hydrolysis reaction in step (2) accounts for 2% of the total mass of triglycerides. The glycerol obtained after the triglyceride and water react has a conversion rate of 2%. The remaining triglycerides undergo ester exchange reaction.
[0047] Embodiment 3:
[0048] A method for preparing biodiesel by non-catalytic alcoholysis comprises the following steps: (1) mixing qualified kitchen waste oil raw materials (water impurity <3%) with methanol, and stirring and reacting them at 200° C. and 2.0 MPa for 6 hours, wherein fatty acids in waste animal and plant oils react with methanol to generate fatty acid methyl esters and water;
[0049] Among them, the chemical reaction between fatty acids and methanol is R-COOH+CH3OH→R-COOH3+H2O;
[0050] The fatty acid mass in the waste animal and plant oils and fats accounts for 30% of the total mass, and the triglyceride content in the waste animal and plant oils and fats is 70%.
[0051] The mass of fatty acid methyl ester obtained after the reaction of fatty acid and methanol is 97% of the total mass of fatty acid, and the conversion rate reaches 97%.
[0052] (2) hydrolyzing part of the triglycerides in the waste animal and vegetable oils in step (1) with the water in step (1) at 200° C. and 1.6 MPa, and subjecting the remaining triglycerides to an ester exchange reaction.
[0053] Among them, triglycerides and water undergo hydrolysis reaction, C3H5(OOCR)3+H2O→R-COOH+C3H8O3;
[0054] Triglycerides undergo transesterification reaction: (RCOO)3C3H5+3CH3OH→3RCOOCH3+C3H5(OH)3.
[0055] The mass of the triglyceride that undergoes hydrolysis reaction in step (2) accounts for 3% of the total mass of triglycerides. The glycerol obtained after the triglyceride and water react has a conversion rate of 3%, and the remaining triglycerides undergo ester exchange reaction.
Claims
1. A method for preparing biodiesel by non-catalytic alcoholysis, characterized in that: The method comprises the following steps: (1) mixing waste animal and plant fats and oils with methanol and stirring the mixture at 185°C-200°C and 1.5MPa-2.0MPa for 5-6h, wherein the fatty acids in the waste animal and plant fats and oils react with the methanol to generate fatty acid methyl esters and water; Among them, the chemical reaction between fatty acids and methanol is R-COOH+CH3OH→R-COOH3+H2O; (2) hydrolyzing part of the triglycerides in the waste animal and vegetable oils and fats in step (1) with the water in step (1) at 185° C.-200° C. and 1.5 MPa-1.6 MPa, and transesterifying the remaining triglycerides. Among them, triglycerides and water undergo hydrolysis reaction, C3H5(OOCR)3+H2O→R-COOH+C3H8O3; Triglycerides undergo transesterification reaction: (RCOO)3C3H5+3CH3OH→3RCOOCH3+C3H5(OH)3.
2. The method for preparing biodiesel by non-catalytic alcoholysis according to claim 1, characterized in that: The molar ratio of the waste animal and plant oils to the alcohol oil in methanol is 5:
1.
3. The method for preparing biodiesel by non-catalytic alcoholysis according to claim 1, characterized in that: The mass of the triglyceride portion that undergoes hydrolysis reaction in step (2) accounts for 1-3% of the total triglyceride mass.
4. A device for preparing biodiesel by non-catalytic alcoholysis according to claim 1, characterized in that: The invention comprises a high-pressure tank, wherein a first feed port, a second feed port and a vacuum port are provided on the high-pressure tank, the second feed port is connected to a feed pipe, the feed pipe is connected to a first infusion cavity through a first bearing, a first gear is arranged outside the first infusion cavity, a first motor is arranged inside the high-pressure tank, a first motor base is connected to a top wall of the high-pressure tank, an output end of the first motor is connected to a second gear, the first gear and the second gear are meshed with each other, forming a structure in which the first gear can rotate synchronously with the second gear, the lower end surface of the first infusion cavity is connected to a first liquid guide tube, a second bearing is arranged outside the first liquid guide tube and is connected to a second liquid guide tube through the second bearing The infusion cavity, the third gear is arranged outside the second infusion cavity, the second motor is arranged at the bottom of the first infusion cavity, the second motor base is connected to the lower end surface of the first infusion cavity, the output end of the second motor is connected to the fourth gear, the third gear and the fourth gear are meshed with each other to form a structure in which the third gear and the fourth gear rotate synchronously, the second infusion cavity is connected to the rotating box through several second liquid guide tubes, the heating columns are evenly distributed in the rotating box, several cutting holes are arranged on the rotating box, the liquid permeable holes are evenly distributed on the side walls of the cutting holes, a metal cutting net is arranged in the circular axis surface of the cutting hole, and several heaters are arranged in the high-pressure tank.
5. The device for preparing biodiesel according to claim 4, characterized in that: The rotating box is a rectangular box, one end of the second liquid guide tube is connected to the upper end of the rotating box in the width direction, and the other end of the second liquid guide tube is connected to the lower end surface of the second infusion cavity. The cutting hole passes through the largest rectangular surface on the rotating box. The cutting hole is made by the first cylinder passing through the rotating box, and the circular edges of the first cylinder are respectively sealed and connected to the two largest rectangular surfaces of the rotating box.
6. The device for preparing biodiesel according to claim 5, characterized in that: The first infusion cavity comprises a first hollow cylinder, the upper end of the first cylinder is connected through the second cylinder, the first bearing is located between the outer wall of the feed pipe and the inner wall of the second cylinder, and the first gear is sleeved on the outer wall of the second cylinder.
7. The device for preparing biodiesel according to claim 6, characterized in that: The second infusion cavity comprises a second hollow cylinder, the upper end of the second cylinder is connected through the third cylinder, the second bearing is located between the outer wall of the first liquid guide tube and the inner wall of the third cylinder, and the second gear is sleeved on the outer wall of the third cylinder.
8. The device for preparing biodiesel according to claim 7, characterized in that: The heating column shell is made of heat-conducting metal, a heater heating end is arranged in the heating column shell, a line protection box is arranged on the outside of the rotating box, the line protection box is filled with heat-insulating cotton, the heater line end and the line are located in the line protection box and are wrapped with heat-insulating cotton, the line protection box is connected to the battery placement box, the battery placement box is filled with heat-insulating cotton, and a manhole is arranged on the high-pressure tank.