Process for producing fatty acid through enzymatic hydrolysis of soapstock and production equipment thereof

Abstract

The invention relates to a grease processing method, in particular to a process and production equipment for producing fatty acid through enzymatic hydrolysis of soapstock. The invention aims to provide a process and production equipment for producing fatty acid through enzymatic hydrolysis of nigre, the provided process is simple, energy-saving and environment-friendly, and the provided equipment is low in investment, simple and convenient to operate and convenient to maintain. The technical scheme is as follows: the process for producing fatty acid through enzymatic hydrolysis of nigre comprises the following steps: (1) adjusting the pH value; (2) enzymatic hydrolysis; (3) heating and demulsifying; (4) acidification; (5) washing; and (6) conveying the crude fatty acid to a distillation tower, and separating high-purity fatty acid by distillation. The invention discloses equipment for producing fatty acid by hydrolyzing soapstock through enzyme catalysis. The equipment is characterized by comprising a first static mixer and a hydrolysis kettle, wherein the first static mixer is provided with a fatty acid inlet and a wastewater inlet; and a steam input pipeline for inputting steam and a process water input pipeline for inputting process water are mounted at the top of the hydrolysis kettle.

Description

Technical Field

[0001] The invention relates to a grease processing method, in particular to a process for producing fatty acids by enzyme-catalyzed hydrolysis of soapstock and production equipment thereof. Background Art

[0002] Soapstock is formed in the alkali refining and deacidification step of the refining process when producing oils and fats. In this process, sodium hydroxide solution is used to neutralize the free fatty acids (FFA) in the crude oil into sodium salts of fatty acids and form soap colloids, which carry impurities such as neutral oils and pigments. The entire soap colloid is called soapstock. The amount of soapstock generally accounts for 3%-20% of the crude oil. The amount of soapstock produced during the alkali refining of high-acid-value cottonseed oil and bran oil is more. The composition of soapstock varies with the process and operation, and is roughly: the content of soap (sodium fatty acid) is 30%-40%, the neutral oil (glyceride) is 8%-27%, and the rest is water, protein, carbohydrates, pigments and other substances, among which the total fatty acid content is as high as 40%-60%.

[0003] At present, except for a small amount of soap stock used for soap making, feed production, synthetic surfactants, preparation of bio-oil and extraction of fatty acids at home and abroad, most of the soap stock is not effectively utilized and is discarded, which not only causes a huge waste of resources, but also causes environmental pollution. Fatty acids, as basic industrial raw materials, are widely used in industries such as plastics, food, washing and energy. The rapid development of industry has greatly increased the demand for high-purity, low-cost fatty acids. Therefore, the conversion of fatty acids using discarded soap stock has gradually become a research hotspot in the field of fatty acid production.

[0004] The manufacturing method of fatty acids and fatty acids (CN115404245A) discloses a method for hydrolyzing soapstock by enzyme catalysis. The method requires a high solid content of the soapstock, and the quality of the fat and soap in the soapstock needs to be controlled during hydrolysis. At the same time, a large amount of strongly acidic wastewater will be generated.

[0005] A soapstock / oilstock enzymatic hydrolysis process (CN113699190A) discloses an enzyme-catalyzed soapstock hydrolysis method, which requires the addition of water for conditioning, so a large amount of 15%-20% hydrochloric acid is required for acidification, and a large amount of strongly acidic wastewater is generated.

[0006] An enzymatic extraction process for fatty acids (CN112442423A) discloses an enzyme-catalyzed soapstock hydrolysis method, which uses a complex enzyme and a large amount of organic acid to adjust the pH value. A large amount of sedimentation agent needs to be added in the later stage, and the amount of acidic wastewater generated is large and contains a large amount of salt substances.

[0007] In general, the process has high requirements for the hydrolysis system, and it is difficult to promote industrialization. In addition, the amount of acid used in the process is large, and the wastewater generated is strongly acidic wastewater. The cost of subsequent treatment is high, and it is easy to cause hazards such as equipment corrosion and environmental pollution.

[0008] Therefore, it is necessary to find a convenient, economical and environmentally friendly method for hydrolyzing soapstock, reducing wastewater discharge, especially avoiding the discharge of strongly acidic wastewater, meeting safety and environmental protection requirements, and at the same time being simple and safe to operate and easy to industrialize. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a process and production equipment for producing fatty acids by enzyme-catalyzed soapstock hydrolysis. The provided process is simple and energy-saving and environmentally friendly, and the provided equipment has low investment, simple operation and convenient maintenance.

[0010] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0011] A process for producing fatty acids by enzyme-catalyzed hydrolysis of soapstock comprises the following steps:

[0012] (1) pH adjustment: Soapstock is mixed with strongly acidic wastewater and pumped into a hydrolysis kettle. The material circulation pump is turned on to control the pH value of the reaction system to 6.3-6.9, preferably 6.6-6.7; the temperature of the reaction system is controlled at 58°C-70°C, preferably 63°C-68°C, by circulating hot water;

[0013] (2) Enzyme-catalyzed hydrolysis: adding lipase and controlling the amount of lipase feed, the weight ratio of soapstock to lipase is 1:0.0002-0.0004; after the lipase is added, controlling the temperature and pressure of the reaction system to carry out the heat preservation reaction;

[0014] (3) Heating and demulsification: After the insulation reaction is completed, steam is passed through the reaction system to raise the temperature to 85°C-90°C, and then the material circulation pump is turned off and the system is allowed to stand for stratification. After stratification, the reaction system is divided into three layers, namely, an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0015] (4) Acidification: Open the circulation and add strong acid to adjust the pH value of the reaction system to 2.2-2.3 for acidification reaction. After the reaction is completed, turn off the material circulation pump and let it stand for stratification. After stratification, the water phase is pumped into the strong acid wastewater storage tank;

[0016] (5) Water washing: Turn on the material circulation pump and pump in process water for circulating water washing; after water washing, turn off the material circulation pump and let it stand for stratification. After stratification, the lower water phase is pumped into a strong acid wastewater storage tank and the upper oil phase is pumped into a crude fatty acid storage tank;

[0017] (6) The crude fatty acids are transported to a distillation tower and high-purity fatty acids are separated by distillation.

[0018] The lipase in step (2) is an acid hydrolase, such as NOVOZYM 40119.

[0019] The pH value of the enzyme-catalyzed hydrolysis in step (2) is controlled to be 6.6-6.7, the temperature is controlled to be 63° C.-68° C., and the insulation reaction time is 25-40 hours; the judgment method is that the acid value no longer increases.

[0020] The pressure of the reaction system in step (2) is 0-0.05 MPa for the hydrolysis kettle, the residence time is greater than 3 h, and the pressure of the pressure kettle is 0.25-0.30 MPa, the residence time is 20-30 min;

[0021] The strongly acidic wastewater in step (1) can be replaced by a strong acid or a strong acid aqueous solution.

[0022] The strong acid in step (4) is at least one single acid or mixed acid with a pKa less than 1 among hydrochloric acid, sulfuric acid, nitric acid, benzenesulfonic acid and trichloroacetic acid.

[0023] During the circulating water washing in step (5), the weight ratio of process water to soap stock is 5:12-24, and the washing time is 2 hours.

[0024] The height of the hydrolysis kettle is 8-10m.

[0025] An enzyme-catalyzed soapstock hydrolysis device for producing fatty acids, characterized by:

[0026] The equipment comprises a first static mixer provided with a fatty acid inlet and a wastewater inlet, and a hydrolysis kettle with a steam input pipeline for inputting steam and a process water input pipeline for inputting process water installed on the top; the first static mixer is connected to the hydrolysis kettle through its outlet, and the hydrolysis kettle is connected to the inlet on the top of the hydrolysis kettle body through the outlet at the bottom of the kettle body of the hydrolysis kettle in sequence through a material circulation pump, a reactor and a second static mixer; the outlet of the reactor is also connected to a strongly acidic wastewater storage tank, a crude fatty acid storage tank and a wastewater standing tank through a conveying pipeline;

[0027] The hydrolysis kettle, the strong acid wastewater storage tank, the crude fatty acid storage tank and the wastewater static tank are also connected to the tail gas pipe through pipelines, and the exhaust gas is treated by the tail gas treatment system and then discharged after being qualified;

[0028] The inner cavity of the hydrolysis kettle and the inner cavity of the reaction kettle are respectively provided with hot water circulation pipelines for heating materials, and are respectively equipped with a circulating hot water inlet and a circulating hot water outlet for connecting to an external heat source;

[0029] A steam input pipeline for inputting steam and a process water input pipeline for inputting process water are installed on the top of the hydrolysis kettle body.

[0030] The outlet of the strong acid wastewater storage tank is connected to the wastewater inlet of the first static mixer through a material circulation pump, so that the strong acid wastewater is transported to the first static mixer;

[0031] The outlet of the wastewater standing tank is connected to the process water input pipeline through a material circulation pump, and part of the wastewater in the wastewater standing tank is transported to the hydrolysis kettle as process water, and the rest of the wastewater is transported to the sewage treatment pool through the wastewater delivery pipeline.

[0032] The crude fatty acid storage tank is connected to the distillation tower via a material circulation pump.

[0033] By implementing the above technical solution, the present invention can achieve the following beneficial effects:

[0034] The present invention can greatly reduce the amount of enzyme used in enzyme-catalyzed hydrolysis, and the enzyme cost is significantly reduced;

[0035] The reaction liquid in the present invention is circulated and mixed by a material circulation pump, so that the material and the enzyme can be mixed more evenly and the enzyme-catalyzed hydrolysis efficiency can be improved.

[0036] The present invention controls the hydrolysis pressure and performs step-by-step pressure hydrolysis on the material, thereby effectively improving the efficiency of enzyme-catalyzed hydrolysis.

[0037] The invention directly performs enzymatic hydrolysis reaction on soap stock, then demulsifies at high temperature, separates the lower water phase, and finally acidifies to prepare crude fatty acid, which can effectively reduce the amount of strong acid used; taking sulfuric acid as an example, the amount of sulfuric acid used in the traditional process is 8%-10%, and the amount of sulfuric acid used after the improvement is 3%-4%, and the amount is reduced to less than 50%, which has important economic benefits.

[0038] The method directly performs enzymatic hydrolysis on soapstock, then performs high-temperature demulsification, separates excess water phase, and finally performs acidification to prepare crude fatty acid. Strong acidic wastewater generated by acidification and water washing is used to adjust the pH value of soapstock, thereby avoiding the discharge of strong acidic wastewater. Meanwhile, the addition of strong acidic wastewater increases the water content of the reaction system and increases the hydrolysis rate.

[0039] The method directly performs enzymatic hydrolysis on soapstock, then demulsifies at high temperature, separates excess water phase, and finally acidifies to prepare crude fatty acid. After the enzyme-catalyzed hydrolysis, the soap content in the reaction system is relatively low, and the soapstock emulsification system can be broken by heating to produce a separation phenomenon.

[0040] The method directly performs enzymatic hydrolysis on soap stock, then performs high-temperature demulsification, separates excess water phase, and finally performs acidification to prepare crude fatty acid. The pH value of the discharged wastewater is 6.2-6.5. Although it is still acidic, the acidity is weak, the corrosion to equipment is small, and it is not easy to cause environmental pollution. It can be directly treated in a sewage pool and then discharged.

[0041] The method directly performs enzymatic hydrolysis on soapstock, then performs high-temperature demulsification, separates excess water phase by stratification, and finally performs acidification to prepare crude fatty acids. Compared with the traditional process, the method can greatly reduce water consumption and avoid the discharge of strongly acidic wastewater, and has the advantages of energy saving and environmental protection.

[0042] The present invention directly performs enzymatic hydrolysis reaction on soapstock, then demulsifies at high temperature, separates excess water phase, and finally acidifies to prepare crude fatty acids. The method has simple process, and as long as the pH value of the reaction system and the temperature and time of the enzymatic hydrolysis reaction are well controlled, crude fatty acids with high hydrolysis rate, high yield and high quality can be obtained; the crude fatty acids can be separated into high-purity fatty acid products by distillation.

[0043] The present invention directly performs enzymatic hydrolysis on soapstock, then demulsifies at high temperature, separates excess water phase, and finally acidifies to prepare crude fatty acids. Compared with the traditional process, this method reduces the high-pressure hydrolysis process, greatly reduces equipment investment, and at the same time greatly improves safety in production.

[0044] The manufacturing method provided by the present invention has low equipment cost, simple and safe process, mild reaction conditions, low wastewater, waste gas and solid waste emissions, and has the advantages of economy, energy saving, emission reduction and environmental friendliness.

[0045] The equipment provided by the present invention is composed of conventional equipment, has low investment and is easy to maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a system principle diagram of the equipment for producing fatty acids by enzyme-catalyzed hydrolysis of soapstock according to the present invention.

[0047] Numbers in the figure: 1-hydrolysis kettle; 2-first static mixer; 3-first online pH meter; 4-online thermometer; 5-second online pH meter; 6-online flow meter; 7-reactor; 8-pressure gauge; 9-second static mixer; 10-strong acid wastewater storage tank; 11-crude fatty acid storage tank; 12-wastewater standing tank; 13-material circulation pump. DETAILED DESCRIPTION

[0048] Unless otherwise specified, the technical means used in the present invention are methods known to those skilled in the art. In addition, the embodiments should be understood as illustrative rather than limiting the scope of the present invention, and the essence and scope of the present invention are limited only by the claims. For those skilled in the art, without departing from the essence and scope of the present invention, various changes or modifications to the reaction conditions and separation and extraction conditions in these embodiments also belong to the protection scope of the present invention.

[0049] The present invention is further described in detail below in conjunction with specific embodiments;

[0050] The enzyme-catalyzed soapstock hydrolysis production fatty acid production equipment provided by the present invention is as follows Figure 1 As shown;

[0051] In the production equipment, the first static mixer 2 is provided with a fatty acid inlet and a wastewater inlet, and the outlet of the first static mixer is connected to the material inlet at the top of the kettle body of the hydrolysis kettle 1; the second static mixer 9 is provided with a strong acid inlet and a fatty acid inlet, and the outlet of the second static mixer is connected to the catalyst inlet at the top of the kettle body of the hydrolysis kettle 1 through a pipeline; the inlet of the second static mixer is connected to the outlet of the reactor 7, and the inlet of the reactor is connected to the outlet at the bottom of the kettle body of the hydrolysis kettle through a material circulation pump 13; the outlet of the reactor is also connected to the strong acid wastewater storage tank 10, the crude fatty acid storage tank 11 and the wastewater standing tank 12 through a conveying pipeline;

[0052] The hydrolysis kettle 1, the strong acid wastewater storage tank 10, the crude fatty acid storage tank 11 and the wastewater static tank 12 are also connected to the tail gas pipe through pipelines, and the exhaust gas is discharged after being treated by the tail gas treatment system and is qualified;

[0053] The crude fatty acid storage tank 11 is connected to the distillation tower via a material circulation pump 13 for outputting the crude fatty acid for further processing;

[0054] The outlet of the strong acid wastewater storage tank 10 is connected to the wastewater inlet of the first static mixer through the material circulation pump 13, and the output strong acid wastewater is transported to the first static mixer to participate in the pH value adjustment process of the present invention;

[0055] The outlet of the wastewater settling tank 12 is connected to the process water input pipeline through the material circulation pump 13, and part of the wastewater in the wastewater settling tank is transported to the hydrolysis kettle as process water to participate in the water washing process of the present invention; the rest of the wastewater is transported to the sewage treatment pool through the wastewater delivery pipeline.

[0056] A steam input pipe and a process water input pipe are installed on the top of the hydrolysis kettle for inputting steam and process water required for processing materials; the steam source of the steam input pipe is preferably a boiler, and the process water comes from the wastewater standing tank 12.

[0057] The inner cavity of the hydrolysis kettle and the inner cavity of the reaction kettle are respectively provided with hot water circulation pipelines for heating materials, and are respectively equipped with a circulating hot water inlet and a circulating hot water outlet for connecting to an external heat source (preferably a boiler).

[0058] An online thermometer 4 and a second online pH meter 5 are installed on the hydrolysis kettle.

[0059] A first online pH meter 3 is installed on the output pipeline of the first static mixer 2 .

[0060] A pressure gauge 8 is installed on the reaction kettle 7 .

[0061] Embodiment 1:

[0062] a. pH value adjustment process: control the soap stock sampling flow rate to 20 t / h, the strong acid wastewater sampling flow rate to 10 t / h, observe the pH value in the first online pH meter 3, and the pH value fluctuates between 6.5 and 6.8, and the total feed amount is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle is fed for 4 hours, 80 tons of soap stock are input, and the input amount of strong acid wastewater is determined according to the pH value); turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63°C-68°C, observe the second online pH meter 5, and the pH value is stable at 6.6-6.7;

[0063] b. Enzyme-catalyzed hydrolysis process: When the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump and control the lipase feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount); adjust the hydrolysis kettle pressure to 0.03Mpa and the residence time to 3.3h; adjust the reactor pressure to 0.25MPa and the residence time to Adjust the outlet flow rate of the material circulation pump to 30t / h; after 24h of heat preservation reaction, take samples every 2h to test the acid value. When the acid value is stable and no longer increases, the hydrolysis is completed;

[0064] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction liquid is raised to 95°C by steam. The circulation is turned off, and the reaction liquid is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0065] d. Acidification process: open the material circulation pump, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the material circulation pump and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0066] e. Water washing process: open the material circulation pump, pump in 8 tons of process water, circulate water for 2 hours, close the material circulation pump, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0067] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0068] Embodiment 2:

[0069] a. pH value adjustment process: control the soap stock sampling flow rate to 20t / h, the strong acid wastewater sampling flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed amount is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle is fed for 4 hours, 80 tons of soap stock are input, and the input amount of strong acid wastewater is determined according to the pH value); turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63°C-68°C, observe the second online pH meter, and the pH value is stable at 6.6-6.7;

[0070] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the lipase feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the hydrolysis kettle pressure to 0.05Mpa, and the residence time to 3.5h; adjust the reactor pressure to 0.25MPa, and the residence time to 30min; adjust the material circulation pump outlet flow rate to 30t / h; after 24h of heat preservation reaction, take samples every 2h to detect the acid value, and when the acid value is stable and no longer increases, the hydrolysis is completed;

[0071] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction liquid is raised to 95°C by steam. The circulation is turned off, and the reaction liquid is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0072] d. Acidification process: open the material circulation pump, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the material circulation pump and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0073] e. Water washing process: open the material circulation pump, pump in 8 tons of process water, circulate water for 2 hours, close the material circulation pump, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0074] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0075] Embodiment three:

[0076] a. pH value adjustment process: control the soap stock sampling flow rate to 20t / h, the strong acid wastewater sampling flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed amount is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle is fed for 4 hours, 80 tons of soap stock are input, and the input amount of strong acid wastewater is determined according to the pH value); turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63°C-68°C, observe the second online pH meter, and the pH value is stable at 6.7-6.8;

[0077] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the lipase feed flow rate to 8kg / h (the feed weight for 2 hours is 16kg, 0.02% of the soap stock amount), adjust the hydrolysis kettle pressure to 0Mpa, and the residence time to 3.1h; adjust the reactor pressure to 0.30MPa, and the residence time to 22.5min; adjust the material circulation pump outlet flow rate to 40t / h; after keeping the reaction for 24h, take samples every 2h to detect the acid value, and when the acid value is stable and no longer increases, the hydrolysis is completed;

[0078] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction liquid is raised to 95°C by steam. The circulation is turned off, and the reaction liquid is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0079] d. Acidification process: open the material circulation pump, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the material circulation pump and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0080] e. Water washing process: open the material circulation pump, pump in 8 tons of process water, circulate water for 2 hours, close the material circulation pump, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0081] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0082] Embodiment 4:

[0083] a. pH value adjustment process: control the soap stock sampling flow rate to 20t / h, the strong acid wastewater sampling flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.7-7.0, and the total feed amount is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle is fed for 4 hours, 80 tons of soap stock are input, and the input amount of strong acid wastewater is determined according to the pH value); turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 65°C-70°C, observe the second online pH meter, and the pH value is stable at 6.8-6.9;

[0084] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 65°C-68°C, turn on the lipase feed pump, control the lipase feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the hydrolysis kettle pressure to 0.05Mpa, and the residence time to 3.5h; adjust the reactor pressure to 0.25MPa, and the residence time to 30min; adjust the material circulation pump outlet flow rate to 30t / h; after the heat preservation reaction for 20h, take samples every 2h to detect the acid value, and when the acid value is stable and no longer increases, the hydrolysis is completed;

[0085] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction liquid is raised to 85°C by steam, and the circulation is turned off, and the reaction liquid is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0086] d. Acidification process: open the material circulation pump, pump in concentrated hydrochloric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the material circulation pump and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0087] e. Water washing process: open the material circulation pump, pump in 8 tons of process water, circulate water for 2 hours, close the material circulation pump, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0088] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0089] Embodiment five:

[0090] a. pH value adjustment process: control the soap stock sampling flow rate to 20t / h, the strong acid wastewater sampling flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.2-6.5, and the total feed amount is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle is fed for 4 hours, 80 tons of soap stock are input, and the input amount of strong acid wastewater is determined according to the pH value); turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 58°C-62°C, observe the second online pH meter, and the pH value is stable at 6.3-6.4;

[0091] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the lipase feed flow rate to 8kg / h (the feed weight for 4h is 32kg, 0.04% of the soap stock amount), adjust the hydrolysis kettle pressure to 0.05Mpa, and the residence time to 3.2h; adjust the reactor pressure to 0.25MPa, and the residence time to 24min; adjust the material circulation pump outlet flow rate to 37.5t / h; after the heat preservation reaction for 30h, take samples every 2h to detect the acid value, and when the acid value is stable and no longer increases, the hydrolysis is completed;

[0092] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction liquid is raised to 90°C by steam, and the circulation is turned off, and the reaction liquid is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0093] d. Acidification process: open the material circulation pump, pump in concentrated nitric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the material circulation pump and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0094] e. Water washing process: open the material circulation pump, pump in 8 tons of process water, circulate water for 2 hours, close the material circulation pump, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0095] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0096] Comparative Example 1:

[0097] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the strong acid wastewater injection flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed volume is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 4 hours, 80 tons of soap stock are input, and the input volume of strong acid wastewater is determined by the pH value). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 6.6-6.7;

[0098] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the pressure of the hydrolysis kettle to 0.03Mpa, and the residence time to 3.3h; the pressure of the pressure kettle outlet valve is fully opened to 0.04MPa, and the residence time is 25min; adjust the outlet flow rate of the material circulation pump to 30t / h; after the heat preservation reaction for 24h, take samples every 2h to detect the acid value, and when the acid value is stable and no longer high, the hydrolysis is completed;

[0099] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction solution is raised to 95°C by steam, and the circulation is turned off. The reaction solution is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0100] d. Acidification process: open the circulation, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the circulation and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0101] e. Water washing process: open the circulation, pump in 8 tons of process water, circulate water for 2 hours, close the circulation, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0102] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0103] Comparative Example 2:

[0104] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the strong acid wastewater injection flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed volume is controlled at about 20% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 1 hour, input 20 tons of soap stock, and the input volume of strong acid wastewater is determined by the pH value). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 6.6-6.7;

[0105] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight in 1 hour is 8kg, 0.04% of the soap stock amount), adjust the pressure of the hydrolysis kettle to 0.03Mpa, and the residence time to 2h; adjust the outlet pressure of the reactor to 0.30MPa, and the residence time to 1h; adjust the outlet flow rate of the material circulation pump to 15t / h; after the heat preservation reaction for 24h, take samples every 2h to detect the acid value, and when the acid value is stable and no longer high, the hydrolysis is completed;

[0106] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction solution is raised to 95°C by steam, and the circulation is turned off. The reaction solution is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0107] d. Acidification process: open the circulation, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the circulation and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0108] e. Water washing process: open the circulation, pump in 2 tons of process water, circulate water for 2 hours, close the circulation, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0109] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0110] Comparative Example 3:

[0111] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the strong acid wastewater injection flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed volume is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 4 hours, 80 tons of soap stock are input, and the input volume of strong acid wastewater is determined by the pH value). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 6.6-6.7;

[0112] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the pressure of the hydrolysis kettle to 0.03Mpa, and the residence time to 3.3h; adjust the pressure of the reactor to 0.15MPa, and the residence time to 25min; adjust the outlet flow rate of the material circulation pump to 30t / h; after the heat preservation reaction for 24h, take samples every 2h to detect the acid value, and when the acid value is stable and no longer high, the hydrolysis is completed;

[0113] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction solution is raised to 95°C by steam, and the circulation is turned off. The reaction solution is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0114] d. Acidification process: open the circulation, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the circulation and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0115] e. Water washing process: open the circulation, pump in 8 tons of process water, circulate water for 2 hours, close the circulation, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0116] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0117] Comparative Example 4:

[0118] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the strong acid wastewater injection flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed volume is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 4 hours, 80 tons of soap stock are input, and the input volume of strong acid wastewater is determined by the pH value). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 6.6-6.7;

[0119] b. Enzyme-catalyzed hydrolysis process: when the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the pressure of the hydrolysis kettle to 0.03Mpa, and the residence time to 3.3h; adjust the pressure of the reactor to 0.60MPa, and the residence time to 25min; adjust the outlet flow rate of the material circulation pump to 30t / h; after the heat preservation reaction for 24h, take samples every 2h to detect the acid value, and when the acid value is stable and no longer high, the hydrolysis is completed;

[0120] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction solution is raised to 95°C by steam, and the circulation is turned off. The reaction solution is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0121] d. Acidification process: open the circulation, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the circulation and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0122] e. Water washing process: open the circulation, pump in 8 tons of process water, circulate water for 2 hours, close the circulation, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0123] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0124] Comparative Example 5:

[0125] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the concentrated sulfuric acid injection flow rate to 0.8t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed amount is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 4 hours, 80 tons of soap stock, about 3.2 tons of concentrated sulfuric acid). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 6.6-6.7;

[0126] b. Enzyme-catalyzed hydrolysis process: When the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the hydrolysis kettle pressure to 0.03Mpa, and the residence time to 3.3h; adjust the reactor pressure to 0.25MPa, and the residence time to 25min; adjust the material circulation pump outlet flow rate to 30t / h; after keeping the reaction for 24h, take samples every 2h to detect the acid value. When the acid value is stable and no longer increases, the hydrolysis is completed;

[0127] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction solution is raised to 95°C by steam, and the circulation is turned off. The reaction solution is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0128] d. Acidification process: open the material circulation pump, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the material circulation pump and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0129] e. Water washing process: open the material circulation pump, pump in 8 tons of process water, circulate water for 2 hours, close the material circulation pump, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0130] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0131] Comparative Example 6:

[0132] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the strong acid wastewater injection flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 6.5-6.8, and the total feed volume is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 4 hours, 80 tons of soap stock are input, and the input volume of strong acid wastewater is determined by the pH value). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 6.6-6.7;

[0133] b. Enzyme-catalyzed hydrolysis process: When the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the hydrolysis kettle pressure to 0.03Mpa, and the residence time to 3.3h; adjust the reactor pressure to 0.25MPa, and the residence time to 25min; adjust the material circulation pump outlet flow rate to 30t / h; after keeping the reaction for 24h, take samples every 2h to detect the acid value. When the acid value is stable and no longer increases, the hydrolysis is completed;

[0134] c. Stratification process: After the hydrolysis is completed, the reaction system is separated into an upper oil phase, a middle emulsified layer, and a lower aqueous phase. The lower aqueous phase is pumped into a wastewater standing tank;

[0135] d. Acidification process: open the circulation, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the circulation and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0136] e. Water washing process: open the circulation, pump in 8 tons of process water, circulate water for 2 hours, close the circulation, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0137] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0138] Comparative Example 7:

[0139] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the strong acid wastewater injection flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 5.5-6.0, and the total feed volume is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 4 hours, input 80 tons of soap stock, and the input volume of strong acid wastewater is determined by the pH value). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 5.6-5.7;

[0140] b. Enzyme-catalyzed hydrolysis process: When the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the hydrolysis kettle pressure to 0.03Mpa, and the residence time to 3.3h; adjust the reactor pressure to 0.25MPa, and the residence time to 25min; adjust the material circulation pump outlet flow rate to 30t / h; after keeping the reaction for 24h, take samples every 2h to detect the acid value. When the acid value is stable and no longer increases, the hydrolysis is completed;

[0141] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction solution is raised to 95°C by steam, and the circulation is turned off. The reaction solution is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0142] d. Acidification process: open the circulation, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the circulation and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0143] e. Water washing process: open the circulation, pump in 8 tons of process water, circulate water for 2 hours, close the circulation, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0144] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0145] Comparative Example 8:

[0146] a. pH value adjustment process: control the soap stock injection flow rate to 20t / h, the strong acid wastewater injection flow rate to 10t / h, observe the first online pH meter, the pH value fluctuates between 7.2-7.6, and the total feed volume is controlled at about 80% of the liquid level of the hydrolysis kettle (150 cubic meters of hydrolysis kettle feed for 4 hours, 80 tons of soap stock are input, and the input volume of strong acid wastewater is determined by the pH value). Turn on the material circulation pump, turn on the hot water circulation pump to control the temperature of the reaction system at 63℃-68℃, observe the second online pH meter, and the pH value is stable at 7.3-7.4;

[0147] b. Enzyme-catalyzed hydrolysis process: When the temperature of the reaction system is stabilized at 63°C-68°C, turn on the lipase feed pump, control the feed flow rate to 8kg / h (the feed weight for 4 hours is 32kg, 0.04% of the soap stock amount), adjust the hydrolysis kettle pressure to 0.03Mpa, and the residence time to 3.3h; adjust the reactor pressure to 0.25MPa, and the residence time to 25min; adjust the material circulation pump outlet flow rate to 30t / h; after keeping the reaction for 24h, take samples every 2h to detect the acid value. When the acid value is stable and no longer increases, the hydrolysis is completed;

[0148] c. Heating and demulsifying process: After the hydrolysis is completed, the circulating hot water is turned off, and the temperature of the reaction solution is raised to 95°C by steam, and the circulation is turned off. The reaction solution is allowed to stand for stratification. After stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase. The lower water phase is pumped into a wastewater standing tank;

[0149] d. Acidification process: open the circulation, pump in concentrated sulfuric acid, adjust the pH value of the reaction system to 2.2-2.3, and carry out the acidification reaction for 3 hours. After the reaction is completed, close the circulation and let it stand for stratification. After stratification, the lower aqueous phase is pumped into the strong acid wastewater storage tank;

[0150] e. Water washing process: open the circulation, pump in 8 tons of process water, circulate water for 2 hours, close the circulation, let it stand and separate into layers. After separation, the lower water phase is pumped into the strong acid wastewater storage tank, and the upper oil phase is pumped into the crude fatty acid storage tank.

[0151] f. Crude fatty acids are separated into high-purity fatty acids by distillation.

[0152] The test results of Examples 1 to 3 and Comparative Examples 1 to 5 are listed below:

[0153] Soap stock raw material: pH value 8.06, solid content 36.72%, acid value 110.72 mgKOH / g, saponification value 192.4 mgKOH / g; Table 1:

[0154] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Acid value mgKOH / g 187.3 187.5 184.6 186.6 185.8 Saponification value mgKOH / g 195.7 195.7 195.5 195.6 195.5 Hydrolysis rate % 95.71 95.81 94.42 95.40 95.04 Hydrolysis time h 28 27 38 30 32 Strong acid dosage as a percentage of soap stock 3.5 3.7 3.6 3.9 3.4 Wastewater pH 6.24 6.23 6.25 6.25 6.26

[0155] Table 2:

[0156]

[0157] Note: Soapstock hydrolysis rate % = crude fatty acid acid value / crude fatty acid saponification value * 100%

[0158] Acid value test: Add concentrated sulfuric acid to the sample until the pH value is ≤3, stir and react for 10 minutes, wash with distilled water until the pH value is ≥6, heat and dry the water, and then determine it according to the national standard "GB5009.229-2016 National Food Safety Standard Determination of Acid Value in Food" using hot ethanol indicator titration.

[0159] Saponification value test: Determine according to the national standard "GB / T 5534-2008 Determination of Saponification Value of Animal and Vegetable Fats and Oils", using hot ethanol indicator titration method.

[0160] Crude fatty acids are separated into high-purity fatty acid products through distillation. Since the distillation process is a conventional separation process, it will not be explained or compared in detail.

[0161] From the comparative experiments we can see that:

[0162] 1. When there is no pressure in the pressure reactor during the hydrolysis process, the hydrolysis time will be long and the hydrolysis rate will decrease.

[0163] 2. During the hydrolysis process, if the normal pressure reaction time is too short and the pressure reaction time is too long, the hydrolysis time will be long and the hydrolysis rate will decrease.

[0164] 3. When the pressure of the pressure reactor is too low during the hydrolysis process, the hydrolysis time will be long and the hydrolysis rate will decrease.

[0165] 4. When the pressure in the pressure reactor is too high during the hydrolysis process, the hydrolysis time will be long and the hydrolysis rate will decrease.

[0166] 5. When acid neutralization is used to produce fatty acids, the process hydrolysis rate will be lower than that of acidic wastewater neutralization. At the same time, a large amount of acid will be used, which will produce a large amount of strongly acidic wastewater.

[0167] 6. Reducing the temperature-raising and demulsification process in the fatty acid production process will lead to an increase in the amount of acid used. At the same time, the strongly acidic wastewater cannot be fully reused, and the wastewater discharge will still be strongly acidic.

[0168] 7. In the fatty acid production process, a system pH value that is too low will lead to a decrease in the hydrolysis rate.

[0169] 8. In the fatty acid production process, a too high pH value of the system will lead to an increase in the amount of acid used and a serious decrease in the hydrolysis rate.

Claims

1. A process for producing fatty acids by enzyme-catalyzed hydrolysis of soapstock, comprising the following steps: (1) pH adjustment: Soapstock is mixed with strongly acidic wastewater and pumped into the hydrolysis kettle. The material circulation pump is turned on to control the pH value of the reaction system to 6.6-6.

9. The temperature of the reaction system is controlled at 63°C-68°C by circulating hot water. (2) Enzyme-catalyzed hydrolysis: adding lipase and controlling the amount of lipase feed, the weight ratio of soapstock to lipase is 1:0.0002-0.0004; after the lipase is added, controlling the temperature and pressure of the reaction system to carry out the heat preservation reaction; (3) Heating and demulsification: After the insulation reaction is completed, steam is introduced into the reaction system to raise the temperature to 85°C-95°C, and then the material circulation pump is turned off and the system is allowed to stand for stratification; after stratification, the reaction system is divided into an upper oil phase, a middle emulsified layer, and a lower water phase, and the lower water phase is pumped into a wastewater standing tank; (4) Acidification: Turn on the circulation pump and add strong acid to adjust the pH value of the reaction system to 2.2-2.3 for acidification reaction. After the reaction is completed, turn off the material circulation pump and let it stand for stratification. After stratification, the water phase is pumped into the strong acid wastewater storage tank; (5) Water washing: Turn on the material circulation pump and pump in process water for circulating water washing; After washing, turn off the material circulation pump and let it stand for stratification. After stratification, pump the lower water phase into the strong acid wastewater storage tank and the upper oil phase into the crude fatty acid storage tank; (6) The crude fatty acids are transported to a distillation tower and high-purity fatty acids are separated by distillation.

2. The process for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 1, characterized in that: The pH value of the enzyme-catalyzed hydrolysis in step (2) is controlled to be 6.6-6.9, the temperature is controlled to be 63° C.-68° C., and the insulation reaction time is 25-40 hours; the judgment method is that the acid value no longer increases.

3. The process for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 1, characterized in that: The pressure of the reaction system in step (2) is 0-0.05 MPa for the hydrolysis kettle, the residence time is greater than 3 h, and the pressure of the pressure kettle is 0.25-0.30 MPa, the residence time is 20-30 min.

4. The process for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 1, characterized in that: The strongly acidic wastewater in step (1) can be replaced by a strong acid or a strong acid aqueous solution.

5. The process for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 1, characterized in that: The lipase in step (2) is acid hydrolase NOVOZYM 40119.

6. The process for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 1, characterized in that: The strong acid in step (4) is at least one of hydrochloric acid, sulfuric acid, nitric acid, benzenesulfonic acid and trichloroacetic acid.

7. The process for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 1, characterized in that: During the circulating water washing in step (5), the weight ratio of process water to soap stock is 1:10, and the washing time is 2 hours.

8. An enzyme-catalyzed soapstock hydrolysis production fatty acid equipment, characterized in that: The equipment comprises a first static mixer (2) provided with a fatty acid inlet and a wastewater inlet, and a hydrolysis kettle (1) with a steam input pipeline for inputting steam and a process water input pipeline for inputting process water installed on the top; the first static mixer is connected to the hydrolysis kettle through its outlet, and the hydrolysis kettle is connected to the inlet on the top of the hydrolysis kettle body through the outlet at the bottom of the kettle body of the hydrolysis kettle in sequence through a material circulation pump (13), a reactor (7) and a second static mixer (9); the outlet of the reactor is also connected to a strongly acidic wastewater storage tank (10), a crude fatty acid storage tank (11) and a wastewater standing tank (12) through a conveying pipeline. The hydrolysis kettle, the strong acid wastewater storage tank, the crude fatty acid storage tank and the wastewater static tank are also connected to the tail gas pipe through pipelines, and the exhaust gas is treated by the tail gas treatment system and then discharged after being qualified; The inner cavity of the hydrolysis kettle and the inner cavity of the reaction kettle are respectively provided with hot water circulation pipelines for heating materials, and are respectively equipped with a circulating hot water inlet and a circulating hot water outlet for connecting to an external heat source; A steam input pipeline for inputting steam and a process water input pipeline for inputting process water are installed on the top of the hydrolysis kettle body.

9. The equipment for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 8, characterized in that: The outlet of the strong acid wastewater storage tank is connected to the wastewater inlet of the first static mixer through a material circulation pump, so that the strong acid wastewater is transported to the first static mixer; The outlet of the wastewater standing tank is connected to the process water input pipeline through a material circulation pump, and part of the wastewater in the wastewater standing tank is transported to the hydrolysis kettle as process water, and the rest of the wastewater is transported to the sewage treatment pool through the wastewater delivery pipeline.

10. The equipment for producing fatty acids by enzyme-catalyzed soapstock hydrolysis according to claim 8, characterized in that: The crude fatty acid storage tank is connected to the distillation tower via a material circulation pump.

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