CN108395937B

CN108395937B - Method and system for producing biodiesel

Info

Publication number: CN108395937B
Application number: CN201710066669.4A
Authority: CN
Inventors: 王晶; 李欣; 李磊; 韩天竹; 杨秀娜; 金平
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2017-02-07
Filing date: 2017-02-07
Publication date: 2021-05-04
Anticipated expiration: 2037-02-07
Also published as: CN108395937A

Abstract

The invention discloses a method and a system for producing biodiesel, wherein the method comprises the following steps: (1) adding raw material grease and alcohols into a premixing tank according to a certain proportion for premixing; (2) introducing the premixed liquid-phase material and gas into a gas-liquid mixer for gas-liquid mixing; (3) introducing the gas-liquid mixed material into a horizontal mixing tank of a mixing reactor for esterification reaction; wherein, the horizontal mixing tank does reciprocating linear motion along the horizontal direction under the action of the reciprocating motion device; (4) the esterification reaction product flows through the ejector and enters the product tank, and partial reaction product in the product tank flows back to the ejector and then flows through the ejector and returns to the product tank again. The invention enhances the stability of the system and can continuously operate for a long time on the premise of keeping the large-range efficient mixing and mass transfer performance.

Description

Method and system for producing biodiesel

Technical Field

The invention belongs to the technical field of biodiesel preparation, and relates to a method and a system for producing biodiesel.

Background

Biodiesel, also known as biodiesel, is a clean fuel produced from renewable biological resources such as animal and vegetable fats as raw materials, and has physical and chemical properties very close to or even better than those of petroleum diesel. Biodiesel is a novel pollution-free renewable energy source, and has the advantages of easy degradation, low emission of combustion pollutants, low emission of greenhouse gases and the like. In the industrial production, the biodiesel is generally produced by a chemical method, namely, animal or vegetable oil is used as a raw material and is subjected to ester exchange reaction with low-carbon alcohol such as methanol or ethanol under the action of an acidic or basic catalyst to prepare the biodiesel. The traditional reactor for producing the biodiesel mostly adopts a mechanical stirring reactor, the reactor commonly used in industry is an intermittent kettle type stirring reactor with a stirring facility, and the reactor has the defects of non-uniform back mixing, low stirring efficiency and unsuitability for continuous operation. In order to solve the problem, a novel reactor-impinging stream reactor is provided, because materials in the reactor collide with each other, the contact area of the materials is increased, the heat transfer rate and the mass transfer rate are correspondingly increased, and the chemical reaction influenced by the mass transfer process is promoted.

CN201046396Y discloses a non-rotation vertical circulation impinging stream reactor, wherein two guide cylinders are arranged in the reactor, and propellers are correspondingly arranged in each guide cylinder, the propellers have opposite spiral directions, and are respectively used for pushing fluid to flow from a feed port to a fluid impinging region through the guide cylinders, and the contact area is increased through high-speed impinging, thereby achieving the purpose of strengthening mass transfer. However, since the fluids always tend to follow the streamlines, it is difficult for the fluids in the impingement zone to contact each other, and thus there is a limit to the enhanced mixing in the impingement zone. But also to cause vibration of the propeller and the crankshaft or failure of the shaft seal, leading to mechanical failure.

CN1814344A discloses an impinging stream reactor for liquid phase reaction, wherein two guide shell are installed in the middle of the reactor, one or two pumps are installed outside the reactor, the outlets of the pumps are symmetrically installed on the feeding side of the guide shell, and reaction materials are conveyed by the pumps, flow at high speed through the guide shell and impact oppositely at the center, so that the mixing of the reaction materials is effectively promoted. The reactor uses pumping type external circulation impinging stream to replace a propeller type structure, simplifies the structural design, reduces the cost, and simultaneously reduces the problems of vibration, shaft seal failure and the like caused by the propeller type structure. However, the central area of the reactor has higher fluid velocity, the peripheral fluid velocity is low, the mixing is not very uniform, and in addition, the pumping type circulating impinging stream is adopted, a large amount of fluid is required to be driven by an external machine to collide at high speed, and the energy consumption is higher.

CN1952048A discloses a method for producing biodiesel, in which materials move to the middle part through a guide shell in an impinging stream reactor and impinge oppositely at the middle part to form an impinging area on the impinging surface and the periphery. After the impact, the fluid returns to the left end and the right end of the container through the annular chamber between the guide shell and the inner wall of the container, and then is fed and conveyed to the middle part through the left guide shell and the right guide shell respectively and impacted again, and the repeated circulation is carried out to achieve the purpose of uniform mixing, thereby improving the mass transfer rate. However, the method also adopts pumping type circulating impinging stream, needs external machinery to drive a large amount of fluid to collide at high speed, and has larger energy consumption.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method and a system for producing biodiesel, and the method enhances the stability of the system and can continuously operate for a long time on the premise of keeping large-range efficient mixing mass transfer performance.

The method for producing the biodiesel comprises the following steps:

(1) adding raw material grease and alcohols into a premixing tank according to a certain proportion for premixing;

(2) introducing the premixed liquid-phase material and gas into a gas-liquid mixer for gas-liquid mixing;

(3) introducing the gas-liquid mixed material into a horizontal mixing tank of a mixing reactor for esterification reaction; wherein, the horizontal mixing tank does reciprocating linear motion along the horizontal direction under the action of the reciprocating motion device;

(4) the esterification reaction product flows through the ejector and enters the product tank, and partial reaction product in the product tank flows back to the ejector and then flows through the ejector and returns to the product tank again.

In the method, the grease and the alcohols in the step (1) are common raw materials for producing the biodiesel. The grease is animal and vegetable grease, preferably grease with 10-18 carbon atoms in fatty acid radicals; the alcohol is low molecular weight monohydric alcohol with 1-8 carbon atoms, preferably methanol or ethanol. The molar ratio of the grease to the alcohols is 3: 1-10: 1, preferably 4: 1-8: 1. in the premixing process, catalysts such as KOH and/or NaOH are generally added, the adding amount of the catalysts is 0.1-1% of the total amount of the raw materials, the premixing temperature is 20-130 ℃, the premixing time is 0.1-0.5 hour, and the premixing tank is an industrial common mixing tank.

In the method, the gas in the step (2) is one or more of helium, neon, argon or nitrogen; the ratio of the volume flow of the gas to the total volume flow of the liquid phase material is 1: 5-1: 20, preferably 1: 8-1: 15. the gas-liquid mixer can adopt an industrial common mixing tank, gas is introduced from the bottom of the mixing tank, a bubbler is arranged at a gas inlet in the mixing tank and is immersed in the grease and the alcohols, and the gas escapes from a small hole in the bubbler and then stirs liquid through bubbling to promote gas-liquid mixing; the gas-liquid mixer can also adopt a gas-liquid mixer based on the Venturi principle, such as a jet device and other gas-liquid mixers.

In the method of the invention, the esterification reaction conditions in the step (3) are as follows: the reaction temperature is 30-130 ℃, preferably 50-120 ℃, and the reaction time is 0.5-6 hours. The horizontal mixing tank continuously performs periodic high-frequency reciprocating variable-speed linear motion of firstly accelerating and then decelerating, and then reversely accelerating and then decelerating, wherein the frequency of the reciprocating motion is generally 5-1000 times/second, and preferably 10-600 times/second. The filling coefficient of the horizontal mixing tank is 0.6-0.8, wherein the filling coefficient is the ratio of the volume of the liquid in the mixing tank to the volume of the mixing tank.

In the method, in the step (4), the liquid flowing back in the product tank enters the ejector under the action of the pump and is ejected at a high speed through the nozzle of the ejector, the kinetic energy formed by the high-speed fluid is utilized to generate negative pressure at the throat part of the ejector, so that the liquid flowing out of the reactor is sucked into the ejector, the backflow liquid and the liquid flowing out of the reactor are mixed and ejected at the diffuser pipe of the ejector and then enter the product tank, and the gas in the product tank flows out of the gas outlet and returns to the gas inlet again for recycling. The ejector in the step (4) can also adopt other types of mixers based on the Venturi principle.

The mixing reactor in the method comprises a horizontal mixing tank, a feeding hose, a discharging hose and a reciprocating device; the two ends of the horizontal mixing tank are respectively provided with a feeding hole and a discharging hole, one end of a feeding hose is connected with the feeding hole of the horizontal mixing tank, the other end of the feeding hose is connected with feeding, one end of a discharging hose is connected with the discharging hole of the horizontal mixing tank, and the other end of the discharging hose is connected with discharging; the reciprocating device comprises two parallel guide rails, a spring, a sliding block or a wheel, a base II, a fixed seat, a driving device and a sliding frame; the sliding frame comprises a base I and a connecting plate; the two parallel guide rails are horizontally arranged, the fixed seats are symmetrically fixed at the inner sides of the left and right ends of the two guide rails (namely the fixed seats are respectively fixed at the left and right ends of each guide rail), and the fixed seats are connected with the base II through springs; the sliding frame and the 4 fixed seats are positioned on the same plane and are of rectangular structures formed by 2 bases I which are arranged at the left side and the right side and are vertical to the direction of the guide rail and two connecting plates which are parallel to the guide rail; the base I is in a strip shape, the length of the base I is slightly smaller than the distance between two parallel guide rails, a sliding block or a wheel is installed below the connecting plate, the sliding block or the wheel is provided with a groove, the top of each guide rail is provided with a longitudinal ridge along the length direction, and the longitudinal ridge of each guide rail is meshed with the groove of the corresponding sliding block or the corresponding wheel; the horizontal mixing tank is fixed on a sliding frame of the reciprocating motion device, and the driving device is connected with the base I or the base II; the horizontal mixing tank can be internally provided with a guide plate.

The material of the feeding hose and the discharging hose is determined according to the material property, and generally, a rubber hose, a plastic hose, a corrugated hose, a metal hose and the like can be adopted. The hose has certain length, guarantees that the hose has certain looseness all the time in the reciprocating motion process of blending tank to avoid causing the hose damage or with blending tank and material import and export junction emergence leak. Wherein the feed inlet and the discharge outlet are preferably located on the same horizontal axis.

In the mixing reactor of the invention, the horizontal mixing tank sealing head can be an elliptical, butterfly, conical, spherical or flat-top sealing head.

In the mixing reactor of the present invention, the volume of the horizontal mixing tank is determined according to actual conditions. Be equipped with liquid level detection device in the blending tank, come control feeding or ejection of compact speed through liquid level detection, maintain the liquid level in the blending tank.

In the mixing reactor, the contact surface of the sliding block or the wheel and the guide rail is provided with a groove, the top of the guide rail is provided with a longitudinal ridge along the length direction, and the longitudinal ridge of the guide rail is meshed with the groove of the sliding block or the wheel, so that the sliding block or the wheel is ensured to move linearly along the length direction of the guide rail under the action of the driving device.

In the mixing reactor of the present invention, the slides or wheels are symmetrically arranged in at least 2 pairs, preferably 2 to 4 pairs. The sliding block and the connecting plate can be welded or in threaded connection; each pair of wheels is fixedly connected with a cross shaft, and the shafts are connected with the connecting plates through bearings.

In the mixing reactor, the guide rail has certain guide precision, and the movement is light and stable; to be sufficiently rigid to withstand external loads. The guide rail also has good wear resistance, the guide rail has small wear loss in the use process, the guide rail can automatically compensate or is convenient to adjust after being worn, and the sliding or rolling contact surface between the guide rail and the sliding block or the wheel is smooth enough to reduce the friction resistance.

In the mixing reactor of the invention, the spring connecting the base and the fixed seat has sufficient rigidity and stiffness coefficient, and the diameter of the spring steel wire, the diameter of the spring, the pitch of the spring and the material of the spring are determined according to actual conditions.

In the mixing reactor of the invention, the distance between the longitudinal ridges of the two parallel guide rails is 1.1 to 1.5 times, preferably 1.2 to 1.4 times, the diameter of the mixing tank, and the two ends of the guide rails are flush with or slightly exceed the outer ends of the fixed seats.

In the mixing reactor of the invention, the horizontal mixing tank is fixedly connected with the two connecting plates of the sliding frame. The connecting plate can be welded with the mixing tank; or a bulge is arranged on the connecting plate to clamp the mixing tank; or welding a pad plate on the mixing tank and then connecting the pad plate with the connecting plate through bolts.

In the mixing reactor, the range between the fixed seats at the left end and the right end of the guide rail is the reciprocating motion space of the sliding frame; the horizontal mixing tank on the sliding frame makes reciprocating linear motion between the left and right fixed seats along the guide rail, and the base I and the base II collide and contact periodically in the reciprocating motion process.

In the mixing reactor of the invention, the length of the connecting plate is slightly larger than the length of the mixing tank, and preferably 1.1 to 1.2 times of the length of the mixing tank.

In the mixing reactor, the distance between the fixed seats at the left end and the right end of the same guide rail is not less than 1.1 times, preferably 1.1-1.3 times of the distance between the bases I corresponding to the fixed seats.

In the mixing reactor of the invention, the driving device can use electric, pneumatic, hydraulic drive or magnetic drive, etc.; when the electric, pneumatic and hydraulic driving is adopted, the driving device is connected with the base I4-3 and acts on the base I4-3, and when the magnetic driving is adopted, the driving device is preferably connected with the base II 4-6, and the mixing tank carries out reciprocating variable-speed linear motion by continuously reversing driving or changing the direction of a magnetic pole.

Under the action of the driving device, the mixing tank performs left-right reciprocating variable-speed linear motion. Under the action of a driving device, the horizontal mixing tank performs reciprocating variable-speed linear motion; firstly, the horizontal mixing tank moves towards one side uniformly and acceleratedly under the action of driving force, after a base I on the side is contacted with a base II on a guide rail, a spring between the base II and a fixed seat is continuously compressed to generate elastic deformation, and the kinetic energy of the horizontal mixing tank is converted into the elastic potential energy of the spring; along with the gradual compression of the spring, the moving speed of the horizontal mixing tank is continuously reduced under the action of the spring force until the speed of the horizontal mixing tank is reduced to zero; then, the horizontal mixing tank moves to the other side in an accelerating way under the action of the driving force of the side and the elasticity of the compressed spring, when the base I on the other side is just contacted with the base II on the guide rail, the horizontal mixing tank reaches the maximum speed, the horizontal mixing tank starts to move in a decelerating way along with the continuous compression of the spring between the base II and the fixed seat under the action of the elastic force of the spring, and the speed of the horizontal mixing tank is reduced to zero; the motion direction of the mixing tank is changed again under the action of the driving force and the spring elasticity, and the horizontal mixing tank reciprocates periodically, so that materials in the tank and the inner wall of the reactor and mixed materials are continuously impacted in all directions at all positions, the materials are promoted to be mixed, the material mass transfer is strengthened, and the reaction efficiency between the materials is improved.

The mixing reactor drives the horizontal mixing tank to do high-frequency reciprocating variable-speed linear motion through the reciprocating motion device, in a motion interval, the mixing tank does accelerated motion under the action of the driving device, the speed of the mixing tank is gradually reduced to zero in the process that the spring is compressed under the action of the elastic force of the spring, and then the mixing tank does periodic high-frequency reciprocating variable-speed linear motion with reverse acceleration and deceleration. In the movement process of the mixing tank, the speed of the mixing tank is increased or decreased, the speed at any moment is changed, and the gas-liquid mixture in the mixing tank moves at a variable speed along with the mixing tank. Because the self inertial force of the materials in the tank acts, the mixed materials and the inner wall of the mixing tank and the mixed materials continuously impact each other in each position and each direction, and the existence of dead zones is avoided. The material that gets into horizontal blending tank is preliminary gas-liquid mixture state, after the high frequency reciprocating variable speed linear motion of horizontal blending tank, further promote gas-liquid mixture, make whole materials form the gas-liquid mixture of misce bene, the area of contact of grease with the alcohol has been increased, the microcosmic backmixing effect of reactor has been strengthened, grease and alcohol can reach molecular level's mixed effect, thereby realize on a large scale intensive mass transfer and reaction between grease and the alcohol, make the material all can the intensive mixing and react in each position all directions in the blending tank, reaction rate has been accelerated, reaction time has been shortened greatly, mass transfer and production efficiency have been improved. Meanwhile, the spring also plays a role in buffering, so that the impact force between the mixing tank and the reciprocating motion device is small, and the stable operation of the device is facilitated. The operation can be stably carried out by both batch operation and continuous operation, and the continuous operation is preferred. Overcomes the defects that only the main impact area of the prior common impact flow reactor has good mixing condition and the other areas have weak mixing and the impact flow reactor is not suitable for continuous operation, and can stably and efficiently run for a long time.

The system for producing biodiesel mainly comprises: the system comprises a premixing tank, a gas-liquid mixer, a mixing reactor, an ejector, a pump and a product tank; the premixing tank is provided with a grease feeding hole, an alcohol feeding hole and a premixed material outlet; the gas-liquid mixer is provided with a liquid phase inlet, a gas phase inlet and a gas-liquid mixed material outlet; the mixing reactor comprises a horizontal mixing tank, a feeding hose, a discharging hose and a reciprocating device; the product tank is provided with a material inlet, a reflux port, a product discharge port and a gas outlet; the outlet of the premixed material of the premixing tank is connected with the liquid phase inlet of the gas-liquid mixer through a pipeline, the outlet of the gas-liquid mixed material of the gas-liquid mixer is connected with the feeding hose of the mixing reactor, the discharging hose of the mixing reactor is connected with the feeding inlet of the ejector, the outlet of the ejector is connected with the inlet of the product tank through a pipeline, the bottom of the product tank is provided with a reflux liquid outlet, the reflux liquid outlet is connected with the reflux inlet of the ejector through a pipeline, and the gas returns to the gas phase inlet for recycling after flowing out from the gas outlet of the product tank.

The invention adopts the mixing reactor as a reactor for producing biodiesel, the gas-liquid mixed material which is preliminarily mixed after being acted by the gas-liquid mixer is introduced into the reactor, and a large-range impact area is formed in the reactor by means of the high-frequency reciprocating variable-speed linear motion of the reactor, so that the preliminarily mixed gas-liquid mixed material is further mixed, all the materials form a uniformly mixed gas-liquid mixture, the contact area of raw material grease and alcohols is increased, the grease and the alcohols in the reactor are fully mixed, the molecular-level mixing effect is achieved, the micro-mixing and micro-mass transfer are greatly enhanced, the reaction rate is accelerated under mild reaction conditions, the reaction time is shortened, and the mass transfer and production efficiency are improved. The system has simple structure, is easy to install and maintain, simplifies the process flow, reduces the production cost and the investment of the reactor, does not discharge waste liquid in the production process, and is a green and environment-friendly process method.

Drawings

FIG. 1 is a schematic diagram of a system for producing biodiesel according to the present invention.

Fig. 2 is a front view of the mixing reactor of the present invention.

Fig. 3 is a top view of a mixing reactor of the present invention.

Wherein 8-grease feed inlet; a 9-alcohol feed inlet; 10-a premixing tank; 11-an ejector; 12-a product tank; 13-a pump; 14-product outlet; 15-a mixing reactor; 16-a gas outlet; 17-gas-liquid mixer; 18-a bubbler; 19-gas phase inlet;

the mixing reactor comprises: 1-reactor feed; 2-reactor feed hose; 3-a horizontal mixing tank; 4-a reciprocating device; 5-reactor discharge hose; 6-discharging the reactor; 7-liquid level detection means;

the reciprocating device 4 includes: 4-1-guide rail, 4-2-spring, 4-3-base I, 4-4-connecting plate, 4-5-slide block or wheel, 4-6-base II, 4-7-fixing seat, 4-8-driving device and 4-9-sliding frame.

Detailed Description

The method and system for producing biodiesel according to the present invention will be described with reference to the accompanying drawings.

The system for producing biodiesel mainly comprises: a premixing tank 10, a gas-liquid mixer 17, a mixing reactor 15, an ejector 11, a pump 13 and a product tank 12. The premixing tank 10 is provided with a grease inlet 8, an alcohol inlet 9 and a premixed material outlet; the gas-liquid mixer 17 is provided with a liquid phase inlet, a gas phase inlet 19 and a gas-liquid mixed material outlet; the mixing reactor 15 comprises a horizontal mixing tank 3, a feeding hose 2, a discharging hose 5 and a reciprocating device 4; the product tank 12 is provided with a material inlet, a return port, a product outlet 14 and a gas outlet 16. The outlet of the premixed material of the premixing tank 12 is connected with the premixed material inlet of the gas-liquid mixer 17 through a pipeline, the outlet of the gas-liquid mixed material of the gas-liquid mixer 17 is connected with the feeding hose 2 of the mixing reactor 15, the discharging hose 5 of the mixing reactor 15 is connected with the feeding inlet of the ejector 11, the outlet of the ejector 11 is connected with the inlet of the product tank 12 through a pipeline, the bottom of the product tank 12 is provided with a reflux liquid outlet, the reflux liquid outlet is connected with the reflux inlet of the ejector 11 through a pipeline, and the gas returns to the gas phase inlet 19 for recycling after flowing out from the gas outlet 16 of the product tank 12.

The system for producing biodiesel of the present invention operates as follows:

raw material grease and alcohols are respectively added into a premixing tank 10 from a grease inlet 8 and an alcohols inlet 9 according to a certain proportion for premixing; after the raw material grease and the alcohols are preliminarily premixed, the grease and the alcohols after preliminary premixing are introduced into a gas-liquid mixer 17, and gas is introduced into the gas-liquid mixer 17 according to a certain proportion, so that the gas and the liquid-phase material are fully subjected to gas-liquid mixing; the primarily mixed gas-liquid material enters a horizontal mixing tank 3 through a feeding hose 2 of a mixing reactor 15 for esterification reaction, wherein the horizontal mixing tank 3 makes reciprocating linear motion under the action of a reciprocating motion device 4; the esterification reaction product flows through the ejector 11 and enters the product tank 12, after part of the reaction product in the product tank 12 flows back to the ejector 11 through the pump 13, the reaction product is ejected at high speed through the nozzle of the ejector 11, the kinetic energy formed by the high-speed fluid generates negative pressure at the throat part of the ejector 11, and the liquid flowing out of the mixing reactor 15 is sucked into the ejector 11 and returns to the product tank 12 again; the gas in the product tank 12 flows out of the gas outlet 16 and is returned to the gas inlet 19 for recycling.

Example 1

Taking soybean oil and methanol as raw materials, wherein the molar ratio of the soybean oil to the methanol is 6: 1, KOH is used as the catalyst, and the content of the KOH is only 0.1 percent of the total amount of the feed. Introducing soybean oil, methanol and a catalyst into a premixing tank, introducing the premixed soybean oil and methanol into a gas-liquid mixing tank, and simultaneously introducing nitrogen into the gas-liquid mixing tank, wherein the ratio of the volume flow of the nitrogen to the total volume flow of the grease and the alcohols is 1: 12. the raw materials of soybean oil, methanol and gas are preliminarily mixed in a gas-liquid mixer and then are introduced into a mixing reactor. The displacement of the reciprocating motion of the mixing reactor is 2 times of the length of the reactor, the reciprocating motion frequency is 200 times/second, the reaction time is 1h, the filling coefficient of the horizontal mixing tank is 0.8, and the feeding rate and the discharging rate are 1/20 of the volume of the mixing tank. The reaction product flowing out from the outlet pipeline of the product tank is subjected to standing separation to obtain a fatty acid ester phase (upper layer), and the conversion rate of the fatty acid triglyceride is measured to be up to 95.7 percent by utilizing a 6890N gas chromatograph of Agilent company.

Example 2

Palm oil and methanol are used as raw materials, and the molar ratio of the palm oil to the methanol is 6: 1, KOH is used as the catalyst, and the content of the KOH is only 0.1 percent of the total amount of the feed. Introducing palm oil, methanol and a catalyst into a premixing tank, introducing the premixed palm oil and methanol into a gas-liquid mixing tank, and simultaneously introducing helium into the gas-liquid mixing tank, wherein the ratio of the volume flow of the helium to the total volume flow of the grease and the alcohols is 1: 12. the raw materials of palm oil, methanol and gas are preliminarily mixed in a gas-liquid mixer and then introduced into a mixing reactor, the displacement of the reciprocating motion of the mixing reactor is 2 times of the length of the reactor, the reciprocating motion frequency is 200 times/second, the reaction time is 1h, the filling coefficient of a horizontal mixing tank is 0.8, and the feeding rate and the discharging rate are 1/20 of the volume of the mixing tank. The reaction product flowing out from the outlet pipeline of the product tank is subjected to standing separation to obtain a fatty acid ester phase (upper layer), and the conversion rate of the fatty acid triglyceride is up to 96.3% by utilizing a 6890N gas chromatograph of Agilent company.

Example 3

The mixing reactor was reciprocated by a displacement of 2 times the length of the reactor in the same manner as in example 1, except that the frequency of reciprocation was 300 times/sec. The reaction product flowing out from the outlet pipeline of the product tank is subjected to standing separation to obtain a fatty acid ester phase (upper layer), and the conversion rate of the fatty acid triglyceride is measured to be up to 98.2% by utilizing a 6890N gas chromatograph of Agilent company.

Example 4

The procedure of example 1 was followed except that the ratio of the volume flow rate of nitrogen to the total volume flow rate of fats and oils and alcohols was 1: 10. the reaction product flowing out from the outlet pipeline of the product tank is subjected to standing separation to obtain a fatty acid ester phase (upper layer), and the conversion rate of the fatty acid triglyceride is up to 99.1% by utilizing 6890N gas chromatograph of Agilent company for analysis.

Comparative example 1

CN1952048A discloses a method for producing biodiesel, wherein methanol and cottonseed oil are used as raw materials for producing biodiesel, and the molar ratio of methanol to cottonseed oil is 10: 1 (catalyst content below 1.0% of the total mass of the feed), the feed rate of methanol and cottonseed oil being equal to the impinging stream reaction volume (i.e. feed volume space velocity of 1 h)^-1I.e. a reaction time of 1 h). After premixing methanol and cottonseed oil in a tundish, pumping the premixed methanol and cottonseed oil into an impinging stream reactor through a pump, and carrying out ester exchange reaction through impingement, wherein the amount of circulating materials is 95% of the feeding amount. The reaction product flowing out of the discharge port of the static mixer was subjected to standing separation to obtain a fatty acid ester phase (upper layer), and the conversion of fatty acid triglyceride was determined to be 100% and the content of methyl ester in the fatty acid ester phase was determined to be 91.1% by gas chromatograph analysis.

Claims

1. A method for producing biodiesel, characterized by comprising the steps of: (1) adding raw material grease and alcohols into a premixing tank according to a certain proportion for premixing; (2) introducing the premixed liquid-phase material and gas into a gas-liquid mixer for gas-liquid mixing; the gas is one or more of helium, neon, argon or nitrogen; (3) introducing the gas-liquid mixed material into a horizontal mixing tank of a mixing reactor for esterification reaction; wherein, the horizontal mixing tank does reciprocating linear motion along the horizontal direction under the action of the reciprocating motion device; (4) the esterification reaction product flows through the ejector and enters the product tank, and partial reaction product in the product tank flows back to the ejector and then flows through the ejector and returns to the product tank again; the mixing reactor comprises a horizontal mixing tank, a feeding hose, a discharging hose and a reciprocating device; the two ends of the horizontal mixing tank are respectively provided with a feeding hole and a discharging hole, one end of a feeding hose is connected with the feeding hole of the horizontal mixing tank, the other end of the feeding hose is connected with feeding, one end of a discharging hose is connected with the discharging hole of the horizontal mixing tank, and the other end of the discharging hose is connected with discharging; the reciprocating device comprises two parallel guide rails, a spring, a sliding block or a wheel, a base II, a fixed seat, a driving device and a sliding frame; the sliding frame comprises a base I and a connecting plate; the two parallel guide rails are horizontally arranged, the fixed seats are symmetrically fixed on the inner sides of the left and right ends of the two guide rails, and the fixed seats are connected with the base II through springs; the sliding frame and the 4 fixed seats are positioned on the same plane and are of rectangular structures formed by 2 bases I which are arranged at the left side and the right side and are vertical to the direction of the guide rail and two connecting plates which are parallel to the guide rail; the base I is in a strip shape, the length of the base I is slightly smaller than the distance between two parallel guide rails, a sliding block or a wheel is installed below the connecting plate, the sliding block or the wheel is provided with a groove, the top of each guide rail is provided with a longitudinal ridge along the length direction, and the longitudinal ridge of each guide rail is meshed with the groove of the corresponding sliding block or the corresponding wheel; the horizontal mixing tank is fixed on a sliding frame of the reciprocating motion device; the driving device is connected with the base I or the base II.

2. The method of claim 1, wherein: the molar ratio of the grease and the alcohols in the step (1) is 3: 1-10: 1, the premixing temperature is 20-130 ℃, and the premixing time is 0.1-0.5 h.

3. The method of claim 1, wherein: the ratio of the volume flow of the gas to the total volume flow of the liquid-phase material in the step (2) is 1: 5-1: 20.

4. the method of claim 1, wherein: the esterification reaction conditions in the step (3) are as follows: the reaction temperature is 30-130 ℃, and the reaction time is 0.5-6 hours.

5. The method of claim 1, wherein: and (4) continuously carrying out periodic high-frequency reciprocating variable-speed linear motion of firstly accelerating and then decelerating, and then reversely accelerating and then decelerating by the horizontal mixing tank in the step (3), wherein the frequency of the reciprocating motion is 5-1000 times/second.

6. The method of claim 1, wherein: and (4) the filling coefficient of the horizontal mixing tank in the step (3) is 0.6-0.8, wherein the filling coefficient is the ratio of the volume of the liquid in the mixing tank to the volume of the mixing tank.

7. The method of claim 1, wherein: the sliding blocks or the wheels are symmetrically arranged, and the number of the sliding blocks or the wheels is at least 2 pairs.

8. The method of claim 1, wherein: the distance between the longitudinal ridges of the two parallel guide rails in the mixing reactor is 1.1-1.5 times the diameter of the mixing tank.

9. The method of claim 1, wherein: the horizontal mixing tank is fixedly connected with the two connecting plates of the sliding frame.

10. The method of claim 1, wherein: the range between the fixed seats at the left end and the right end of the guide rail is the reciprocating motion space of the sliding frame; the horizontal mixing tank on the sliding frame makes reciprocating linear motion between the left and right fixed seats along the guide rail, and the base I and the base II collide and contact periodically in the reciprocating motion process.

11. The method of claim 1, wherein: the driving device adopts one of electric drive, pneumatic drive, hydraulic drive or magnetic drive.

12. A system using the method for producing biodiesel according to claim 1, characterized by comprising: the system comprises a premixing tank, a gas-liquid mixer, a mixing reactor, an ejector and a product tank; the premixing tank is provided with a grease feeding hole, an alcohol feeding hole and a premixed material outlet; the gas-liquid mixer is provided with a liquid phase inlet, a gas phase inlet and a gas-liquid mixed material outlet; the mixing reactor comprises a horizontal mixing tank, a feeding hose, a discharging hose and a reciprocating device; the product tank is provided with a material inlet, a reflux port, a product discharge port and a gas outlet; the outlet of the premixed material of the premixing tank is connected with the liquid phase inlet of the gas-liquid mixer through a pipeline, the outlet of the gas-liquid mixed material of the gas-liquid mixer is connected with the feeding hose of the mixing reactor, the discharging hose of the mixing reactor is connected with the feeding inlet of the ejector, the outlet of the ejector is connected with the inlet of the product tank through a pipeline, the bottom of the product tank is provided with a reflux liquid outlet, the reflux liquid outlet is connected with the reflux inlet of the ejector through a pipeline, and the gas returns to the gas phase inlet for recycling after flowing out from the gas outlet of the product tank.