阅读说明：本技术 一种阶梯逆流式连续酶促法制备生物柴油的工艺系统 (Process system for preparing biodiesel by adopting step counter-flow continuous enzymatic method ) 是由 李伍 种裕瀚 李道强 江建 黄晗名 王世普 于 2019-10-18 设计创作，主要内容包括：本发明提供一种阶梯逆流式连续酶促法制备生物柴油的工艺系统,其特征在于,包括多级酶法反应装置、降酸装置、混合罐、油脂原料罐,所述多级酶法反应装置包括至少一个酶法反应单元,所述酶法反应单元包括设有原料入口的反应器、与所述反应器连接的离心机21、并联与所述离心机的重相膜过滤器及油相膜过滤器,所述油相膜过滤器设有用于将甲酯排入降酸装置的甲酯排出口及用于将甲醇回流至混合罐的甲醇回流口,所述重相膜过滤器设有甘油排出口及用于将生物酶回流至混合罐的生物酶回流口,以解决在生物酶法制备的生物柴油反应速率慢、反应不彻底、产品酸价不达标的问题,节能降耗。(The invention provides a process system for preparing biodiesel by a step counter-current continuous enzymatic method, which is characterized by comprising a multistage enzymatic reaction device, an acid reducing device, a mixing tank and a grease raw material tank, wherein the multistage enzymatic reaction device comprises at least one enzymatic reaction unit, the enzymatic reaction unit comprises a reactor provided with a raw material inlet, a centrifuge 21 connected with the reactor, a heavy phase membrane filter and an oil phase membrane filter which are connected with the centrifuge in parallel, the oil phase membrane filter is provided with a methyl ester discharge port used for discharging methyl ester into the acid reducing device and a methanol return port used for returning methanol to the mixing tank, the heavy phase membrane filter is provided with a glycerin discharge port and a biological enzyme return port used for returning biological enzyme to the mixing tank, so as to solve the problems that the reaction rate of the biodiesel prepared by the biological enzymatic method is slow, the reaction is incomplete and the acid value of a product does not reach the standard, energy conservation and consumption reduction.)

1. The process system for preparing the biodiesel by the step counter-flow continuous enzymatic method is characterized by comprising a multistage enzymatic reaction device, an acid reducing device (14), a mixing tank (5) and a grease raw material tank, wherein the multistage enzymatic reaction device comprises at least one enzymatic reaction unit, the enzymatic reaction unit comprises a reactor provided with a raw material inlet, a centrifuge (21) connected with the reactor, a heavy phase membrane filter (31) connected with the centrifuge (21) in parallel and an oil phase membrane filter (41), the oil phase membrane filter (41) is provided with a methyl ester discharge port for discharging methyl ester into the acid reducing device (14) and a methanol return port for returning the methanol to the mixing tank (5), and the heavy phase membrane filter (31) is provided with a glycerol discharge port and a biological enzyme return port for returning the biological enzyme to the mixing tank (5).

2. The process system for preparing biodiesel according to the claim 1, it is characterized in that the multi-stage enzyme method reaction device comprises a first-stage enzyme method reaction unit and a last-stage enzyme method reaction unit, the mixing tank (5) is connected with a reactor (13) of the final-stage enzyme reaction unit, the grease raw material tank is connected with the reactor of the first-stage enzyme method unit, the methyl ester discharge port of the first-stage enzyme method unit is connected with the reactor (13) of the last-stage enzyme method unit, the methyl ester discharge outlet of the final-stage enzyme reaction unit is connected with the acid reduction device (14), the methanol return port and the biological enzyme return port of the first-stage enzyme reaction unit are connected with the mixing tank (5), the methanol return port and the biological enzyme return port of the final-stage enzyme method unit are connected with the reactor (11) of the first-stage enzyme method reaction unit.

3. The process system for preparing biodiesel according to claim 1, wherein the multistage enzymatic reaction device comprises a first-stage enzymatic reaction unit, a middle-stage enzymatic reaction unit and a last-stage enzymatic reaction unit, the mixing tank (5) is connected with the reactor (13) of the last-stage enzymatic reaction unit, the grease raw material tank is connected with the reactor (11) of the first-stage enzymatic reaction unit, the methyl ester discharge port of the last-stage enzymatic reaction unit is connected with the acid reduction device (14), the methyl ester discharge port of the first-stage enzymatic reaction unit is connected with the reactor (12) of the middle-stage enzymatic reaction unit, the methyl ester discharge port of the middle-stage enzymatic reaction unit is connected with the reactor (13) of the last-stage enzymatic reaction unit, and the methanol return port and the biological enzyme return port of the first-stage enzymatic reaction unit are connected with the mixing tank (5), the methanol return port and the biological enzyme return port of the middle-stage enzyme reaction unit are connected with the reactor (11) of the first-stage enzyme reaction unit, and the methanol return port and the biological enzyme return port of the last-stage enzyme reaction unit are connected with the reactor (12) of the middle-stage enzyme reaction unit.

4. The process system for preparing biodiesel according to the claim 2, wherein said multi-stage enzymatic reaction device comprises at least one intermediate-stage enzymatic reaction unit.

5. The process system for preparing biodiesel according to claim 1, wherein said acid-reducing device (14) is provided with a methyl ester connection port, an input port for inputting an acid-reducing agent, and an exhaust port for exhausting biodiesel.

6. The process system for the stepwise countercurrent continuous enzymatic biodiesel production according to claim 1 wherein the heavy phase membrane filter (31) comprises a metal membrane filter having a filter pore size of 40-100nm and a ceramic membrane filter having a filter pore size of 5-50nm, and the oil phase membrane filter (41) comprises a ceramic membrane filter having a filter pore size of 5-50 nm.

7. The system of claim 1, wherein the reactor is provided with a transfer pump.

Technical Field

The invention relates to the field of biodiesel industrial production, in particular to a process system for preparing biodiesel by a step counter-flow continuous enzymatic method.

Background

The energy crisis is a great challenge to humans in the middle of this century. Petroleum is the most widely used energy source. The latest estimate in the world is that the steady supply of oil on the earth will not exceed 20 years, and the exhaustion period is only 50 years. China is a country with relatively poor petroleum resources, and with the rapid increase of national economy, the petroleum resources of China are becoming increasingly scarce. Therefore, the measures are actively taken in China, the investment of technical development of basic research of alternative energy is increased, the strategy of energy diversification is realized, and the excessive dependence on petroleum resources is reduced. In recent years, biofuel is considered as a potential alternative energy source, wherein biodiesel has strong competitiveness in the aspects of technical advancement, technical maturity, economy, supporting facility construction and the like, and is a new energy source with great development potential. Biodiesel is a renewable biological energy source which can be transported and stored, and the main raw materials of the biodiesel are vegetable oil, animal oil, leftovers after the refining of the vegetable oil, acidified oil, swill oil and swill waste oil and waste animal and vegetable oil after various fried foods. The method for processing the biodiesel by using the waste animal and vegetable oil as the raw material not only relieves the problem of energy shortage, but also solves the problem of food safety to a certain extent.

The biodiesel is a fatty acid short-chain ester substance generated by transesterification or esterification reaction of a biological oil raw material and methanol, is a novel pollution-free and renewable energy source, has attracted extensive attention for research and application, and has a new prospect in the oil industry. The biological diesel oil is superior to petrochemical diesel oil in flash point, combustion efficiency, sulfur content, oxygen content, arene content and oxygen consumption, and has greatly reduced suspended particle, CO, sulfide and hydrocarbon in the tail gas and environment friendship.

At present, biodiesel is mainly produced by a chemical method, a large amount of wastewater containing acid or alkali is generated in the reaction process, and in addition, the purification difficulty of glycerin which is a byproduct of the reaction is higher; the enzymatic method for synthesizing the biodiesel has the advantages of mild reaction conditions, no pollutant emission and the like, and accords with the development direction of safe production and environmental protection, so more and more factories have a willingness to adopt the enzymatic method for the industrial production of the biodiesel.

In the reaction of synthesizing biodiesel by an enzymatic method, the biodiesel is mainly prepared by transesterification and esterification of grease and methanol. In the reaction process, the mixing effect of the grease and the methanol influences the reaction rate, ensures the concentration gradient of the crude biodiesel in the reaction system, can make the reaction rate higher, and makes the reaction system go forward better. The adoption of the step-type countercurrent continuous reaction can well improve the mixing effect of the grease and the methanol and also can ensure that the reaction is stably carried out in the forward and reverse reaction directions.

In the process of transesterification and esterification, the content of glycerin and water which are reaction byproducts is continuously improved, after a certain degree is reached, the reaction reaches balance, the content of biodiesel is not increased along with the reaction, the acid value of the generated crude biodiesel is not reduced, and the acid value of the crude biodiesel needs to be further reduced for producing the biodiesel meeting the national standard. In order to further reduce the acid value of the crude biodiesel, the glycerin and water in the reaction system need to be continuously removed, so that the transesterification and esterification reactions can be carried out in a forward and reverse manner, or a chemical neutralization method is adopted to convert fatty acid in the crude biodiesel into fatty acid salt to be separated from the reaction system.

Disclosure of Invention

In order to solve the problems, the invention provides a process system for preparing biodiesel by a step counter-flow continuous enzymatic method, which aims to solve the problems of slow reaction rate, incomplete reaction and substandard product acid value of the biodiesel prepared by a biological enzymatic method, save energy and reduce consumption.

The technical scheme for solving the problems is to provide a process system for preparing biodiesel by a step counter-flow continuous enzymatic method, which is characterized by comprising a multistage enzymatic reaction device, an acid reducing device, a mixing tank and a grease raw material tank, wherein the multistage enzymatic reaction device comprises at least one enzymatic reaction unit, the enzymatic reaction unit comprises a reactor provided with a raw material inlet, a centrifuge 21 connected with the reactor, a heavy phase membrane filter and an oil phase membrane filter, the heavy phase membrane filter is connected with the centrifuge in parallel, the oil phase membrane filter is provided with a methyl ester discharge port for discharging methyl ester into the acid reducing device and a methanol return port for returning methanol to the mixing tank, and the heavy phase membrane filter is provided with a glycerol discharge port and a biological enzyme return port for returning biological enzyme to the mixing tank.

Preferably, the multistage enzymatic reaction device comprises a first-stage enzymatic reaction unit and a last-stage enzymatic reaction unit, the mixing tank is connected with the reactor of the last-stage enzymatic reaction unit, the grease raw material tank is connected with the reactor of the first-stage enzymatic reaction unit, the methyl ester discharge port of the first-stage enzymatic reaction unit is connected with the reactor of the last-stage enzymatic reaction unit, the methyl ester discharge port of the last-stage enzymatic reaction unit is connected with the deacidification device, the methanol return port and the biological enzyme return port of the first-stage enzymatic reaction unit are connected with the mixing tank, and the methanol return port and the biological enzyme return port of the last-stage enzymatic reaction unit are connected with the reactor of the first-stage enzymatic reaction unit.

Preferably, the multistage enzymatic reaction device comprises a first-stage enzymatic reaction unit, a middle-stage enzymatic reaction unit and a last-stage enzymatic reaction unit, the mixing tank is connected with the reactor of the last-stage enzymatic reaction unit, the grease stock tank is connected with the reactor of the first-stage enzymatic reaction unit, the methyl ester discharge port of the last-stage enzymatic reaction unit is connected with the acid reduction device, the methyl ester discharge port of the first-stage enzymatic reaction unit is connected with the reactor of the middle-stage enzymatic reaction unit, the methyl ester discharge port of the middle-stage enzymatic reaction unit is connected with the reactor of the last-stage enzymatic reaction unit, the methanol return port and the biological enzyme return port of the first-stage enzymatic reaction unit are connected with the mixing tank, the methanol return port and the biological enzyme return port of the middle-stage enzymatic reaction unit are connected with the reactor of the first-stage enzymatic reaction unit, and the methanol return port and the biological enzyme return port of the last-, The biological enzyme return port is connected with the reactor of the middle-level enzyme reaction unit.

Preferably, the multistage enzymatic reaction apparatus comprises at least one intermediate enzymatic reaction unit.

Preferably, the acid reducing device is provided with a methyl ester connecting port, an input port for inputting the acid reducing agent and an exhaust port for discharging the biodiesel.

Preferably, the oil phase membrane filter comprises an oil phase filtration membrane, the heavy phase membrane filter comprises a metal membrane filter with a filtration pore size of 40-100um and a ceramic membrane filter with a filtration pore size of 5-50um, and the oil phase membrane filter comprises a ceramic membrane filter with a filtration pore size of 5-50 um.

Preferably, the reactor is provided with a transfer pump.

The technical system for preparing the biodiesel by the step counter-flow continuous enzymatic method has the following use process and principle: in the initial reaction stage, the raw material oil and fat mixed biological enzyme is added into a reaction tank of a first-stage enzyme reaction unit through an oil raw material tank, and the mass ratio of the oil to the methanol is 1: 0.1 to 0.2, preferably 1: 0.14-0.18, based on the quality of the grease, adding 330-550 standard enzymes with the activity of biological enzymes per gram of biological grease, preferably adding 420-460 standard enzymes with the activity of biological enzymes per gram of biological grease, adding methanol into a reaction tank of a first-stage enzyme method reaction unit through a mixing tank, simultaneously adding the same methanol and biological enzymes into a reactor of a last-stage enzyme method reaction unit in a continuous countercurrent manner, controlling the temperature of the reactor to be 35-40 ℃, carrying out continuous reaction at a stirring speed of 60-240r/min, and changing the raw material feeding of the first-stage enzyme method reaction unit into only the oil raw material when an oil phase filter of the last-stage enzyme method reaction unit has oil phase extraction.

In the scheme, the method can comprise 1-6 stages of enzyme reaction units, such as a first-stage enzyme reaction unit, a middle-stage enzyme reaction unit and a last-stage enzyme reaction unit which are connected in sequence, if a plurality of middle-stage enzyme reaction units are contained, the middle-stage enzyme reaction units exist in an upper-stage and lower-stage mode mutually, the reflux of the biological enzyme and the methanol is realized, the methyl ester is output to the next stage, a centrifugal machine of each stage of enzyme reaction unit separates a product into a heavy phase and an oil phase, the centrifugal machine is a DHZ type disc centrifugal machine, the glycerol and the methyl ester are almost immiscible at the temperature of 40 ℃, the density of the glycerol and the methyl ester has larger density difference, the heavy phase after centrifugation is a mixture of the glycerol, the methanol and the enzyme, the oil phase is a mixture of the methyl ester and the methanol, the heavy phase is separated out the biological enzyme by a heavy phase membrane filter and returned to a previous stage reactor, the heavy phase membrane filter comprises a XKW type metal membrane filter, the pore diameter of the filter membrane of the metal membrane filter is 40-100um, preferably 50-80um, and the pore diameter of the filter membrane of the ceramic membrane filter is 5-50um, preferably 10-30um, for further filtering the filtrate of the metal membrane filter to separate the biological enzyme in the filtrate; the oil phase is separated into methanol by an oil phase membrane filter and returns to the upper stage separator, the oil phase membrane filter comprises a ceramic membrane filter, the ceramic membrane with the membrane aperture of 5-50um, preferably 10-20um, is used for separating the methanol, and the filtered substances are used as reaction raw materials to promote the reaction to be carried out rightwards under the action of a diesel oil delivery pump with the model of KCB-83.3 and the biological enzyme and the methanol which flow back to the upper stage reactor.

The deacidification device can comprise at least one deacidification reactor, the deacidification reactor can be a reaction tank provided with a deacidification agent inlet and outlet, the deacidification agent is conveyed into the reaction tank through an oil pump and then discharged into a recycling bin through an outlet, the deacidification principle is that the deacidification agent reacts with free fatty acid in crude biodiesel collected by a final reactor to enable the acid value of the finally obtained biodiesel to be lower than 0.8mg, wherein the deacidification agent used in the scheme is organic amine and specifically comprises one or more of monoethanolamine, diethanolamine, triethanolamine, diethylamine, triethylamine and ethylenediamine, the stirring speed is 80-300r/min, and the mass ratio of an oil phase to the deacidification agent is 1: 0.006-0.01.

The invention relates to a process system for preparing biodiesel by a step counter-flow continuous enzymatic method, which comprises the following steps:

1. in the traditional enzymatic reaction, raw material grease, biological enzyme and methanol are added into a reactor together, and a plug flow reaction is adopted, so that the raw material grease, the biological enzyme and the methanol are difficult to be fully mixed in the process, the reaction rate is too low, the number of the reactors is increased, and the equipment investment is increased. By adopting the counter-flow reaction, the reactants are fully mixed in the flowing process, the reaction rate is improved, the reaction residence time is reduced, the number of reactors is reduced, and the equipment investment is reduced.

2. In the traditional enzymatic reaction, reaction byproducts are not separated from a reaction system, and fresh methanol is not supplemented, so that the reaction system is balanced too fast, and fatty acid and glyceride in raw material methyl ester are not completely converted into fatty acid methyl ester, so that the product yield is low, and the acid value is too high. The step counter-flow reaction is adopted, the reaction by-product glycerol is separated out of the reaction system in time, and the fresh methanol is continuously supplemented, so that the concentration of raw materials in the reaction system can be improved, the reaction is promoted to be carried out in the positive direction, the reaction is more thorough, the product yield is improved, and the economic benefit is increased.

3. After a reaction system of the traditional enzyme method reaction is balanced, the acid value is difficult to reduce, the acid value is generally stabilized at 4-8mgKOH/g oil, which causes difficulty in refining biodiesel in the later period, and the final product cannot meet the requirements of national standards. The method adopts a neutralization mode to reduce and remove fatty acid in the crude biodiesel and reduce the acid value of the crude biodiesel, and has simple and stable process.

4. In the traditional enzyme method reaction process system, in order to reduce the acid value of the crude biodiesel to be below 0.5-1mgKOH/g oil, an intermittent water distribution process or an online water distribution process is adopted, but both processes need to invest a large amount of high-power equipment, such as a centrifuge, a dehydration molecular sieve, a blower and the like, and a large amount of high-purity raw material methanol is used, so that the production cost is greatly improved.

5. According to the acid reduction reaction system, after free fatty acid is converted into fatty acid salt and is separated from the reaction system, the fatty acid can be recovered by adopting a hydrolysis process, the total yield of the biodiesel is not influenced, the economic benefit of enterprises is not influenced, and compared with the traditional reaction device, the acid reduction reaction system has the advantages of improving the reaction rate, reducing the consumption of raw materials, improving the yield of the biodiesel and reducing the acid value of products.

Drawings

FIG. 1 is a schematic view of a process system for preparing biodiesel by the stepwise countercurrent continuous enzymatic method of the present embodiment;

in the figure: 11. a reactor of the first-order enzymatic reaction unit; 12. a reactor of the medium-level enzymatic reaction unit; 13. a reactor of a final enzymatic reaction unit; 14. a deacidification device; 21. a centrifuge; 31. a heavy phase membrane filter; 41. an oil phase membrane filter; 5. and (4) mixing the materials in a tank.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

The embodiment provides a process system for preparing biodiesel by a step counter-flow continuous enzymatic method, which comprises a multistage enzymatic reaction device, an acid reducing device 14, a mixing tank 5 and a grease raw material tank, wherein the multistage enzymatic reaction device comprises at least one enzymatic reaction unit, the enzymatic reaction unit comprises a reactor provided with a raw material inlet, a centrifuge 21 connected with the reactor, a heavy phase membrane filter 31 connected with the centrifuge 21 in parallel and an oil phase membrane filter 41, the oil phase membrane filter 41 is provided with a methyl ester discharge port for discharging methyl ester into the acid reducing device 14 and a methanol return port for returning methanol to the mixing tank 5, and the heavy phase membrane filter 31 is provided with a glycerol discharge port and a biological enzyme return port for returning biological enzyme to the mixing tank 5.

The multistage enzymatic reaction device comprises a first-stage enzymatic reaction unit and a last-stage enzymatic reaction unit, wherein a mixing tank 5 is connected with a reactor 13 of the last-stage enzymatic reaction unit, a grease raw material tank is connected with the reactor of the first-stage enzymatic reaction unit, a methyl ester discharge port of the first-stage enzymatic reaction unit is connected with the reactor 13 of the last-stage enzymatic reaction unit, a methyl ester discharge port of the last-stage enzymatic reaction unit is connected with an acid reduction device 14, a methanol return port and a biological enzyme return port of the first-stage enzymatic reaction unit are connected with the mixing tank 5, and the methanol return port and the biological enzyme return port of the last-stage enzymatic reaction unit are connected with a reactor 11 of the first-stage enzymatic reaction unit.

The multistage enzyme method reaction device comprises a first-stage enzyme method reaction unit, a middle-stage enzyme method reaction unit and a last-stage enzyme method reaction unit, wherein a mixing tank 5 is connected with a reactor 13 of the last-stage enzyme method reaction unit, a grease raw material tank is connected with a reactor 11 of the first-stage enzyme method reaction unit, a methyl ester discharge port of the last-stage enzyme method reaction unit is connected with an acid reduction device 14, a methyl ester discharge port of the first-stage enzyme method reaction unit is connected with a reactor 12 of the middle-stage enzyme method reaction unit, a methyl ester discharge port of the middle-stage enzyme method reaction unit is connected with the reactor 13 of the last-stage enzyme method reaction unit, a methanol return port and a biological enzyme return port of the first-stage enzyme method reaction unit are connected with the mixing tank 5, and the methanol return port and the biological enzyme return port of the middle-stage enzyme method reaction unit are connected with, the methanol return port and the biological enzyme return port of the final-stage enzyme reaction unit are connected with the reactor 12 of the intermediate-stage enzyme reaction unit.

The multistage enzymatic reaction device comprises at least one intermediate enzymatic reaction unit.

The deacidification device 14 is provided with a methyl ester connecting port, an input port for inputting the deacidification agent and an exhaust port for discharging the biodiesel.

The heavy phase membrane filter 31 comprises a metal membrane filter with a filtering pore size of 40-100nm and a ceramic membrane filter with a filtering pore size of 5-50nm, and the oil phase membrane filter 41 comprises a ceramic membrane filter with a filtering pore size of 5-50 nm.

The reactor is provided with a delivery pump.