Method for reducing the chloride content of oils and / or fats and a method for the hydrolysis thereof

Abstract

The invention relates to a method for reducing the chloride content in lipids, in particular in oils and fats, characterised by the following steps: A providing a first lipid phase (1 or 5) having an increased chloride content; B adding (104) water (9), in particular demineralised water, and an organic acid (10) to the first lipid phase and keeping (105) this mixture (12) at a temperature of more than 140°C and less than 200°C and at a pressure of more than 10 bar and less than 16 bar over a dwell time of more than 2 h; and C separating (107) the mixture (12) into a second lipid phase (14) having a reduced chloride content and a water phase (13), wherein the method does not comprise the addition of a base and does not comprise the addition of a bleaching agent to the first lipid phase (5) or the second lipid phase (14) or the mixture (12). The invention also relates to a method for hydrolysing an oil and / or fat.

Description

[0001] METHOD FOR REDUCING THE CHLORIDE CONTENT OF OILS AND / OR FATS AND A METHOD FOR THEIR HYDROLYSIS

[0002] The present invention relates to a method for reducing the chloride content of oils and / or fats and a method for hydrolyzing oils and fats with reduced chloride content.

[0003] In the oil and fat industry, there is a strong desire to reduce the chloride content in the feedstocks used in hydrolysis as much as possible. Chlorides can, among other things, expose the stainless steel surfaces of processing plants to increased corrosion.

[0004] Therefore, in recent times there has been an increased effort to drastically reduce the chloride content of oils and fats before their hydrolysis.

[0005] The relevant prior art documents identified were CN111909793, US2023 / 0287295 A1, WO 2024 / 074759 A1, and WO2023 / 126478 A1. These documents mostly describe the addition of water and citric acid to fats and oils, followed by heating and separation of the aqueous phase. However, this purification step is considered insufficient in the vast majority of cases. Therefore, bleaching agents, such as bleaching earth or similar substances, must be added. After absorbing components, these must then be removed from the respective fat or oil in an additional separation step, e.g., by filtration.

[0006] The technical effort involved in the process, the disposal, and the associated waste products of bleach are detrimental to efficient process control of the hydrolysis process in general and the initial chloride reduction in particular.

[0007] The object of the present invention is therefore to provide an ecologically and economically significantly improved variant of a process for reducing the chloride content in fats and oils.

[0008] The invention solves this problem by providing the method with the features of claim 1. A method according to the invention serves to reduce the chloride content in lipids, in particular fats and oils, such as animal fats or edible oils. Used fats or oils contain larger quantities of chlorides due to their use, for example, through the addition of table salt. These chlorides are corrosive to the processing equipment in the process, e.g., during hydrolysis. It is therefore necessary to reduce these chlorides in a simple and economical manner. This is achieved within the framework of the method according to the invention at least by the following steps:

[0009] A. Providing a first lipid phase with an increased chloride content, preferably of more than 200 mg / kg, particularly preferably more than 300 mg / kg.

[0010] Ideally, in step A, the product with lower chloride content can be used as crude oil or crude fat and processed directly further. At higher chloride concentrations, an initial washing and phase separation is recommended to reduce the chloride content, primarily removing inorganic chlorides. Organic chlorides generally remain in the light phase after this type of acid degumming.

[0011] B. Addition of water and an organic acid and holding this mixture at a temperature of more than 140°C and less than 200°C and at a pressure of more than 10 bar and less than 16 bar for a residence time of more than 2 hours; and

[0012] In step B, water, specifically demineralized water, and an organic acid are added to the lipid phase. The reaction conditions are between more than 140°C and less than 200°C. A process pressure between 10 bar and less than 16 bar was chosen. It is also important that these process conditions are maintained for more than 2 hours. Fluctuations within the specified parameters are permissible during this maintenance period.

[0013] Step C: Phase separation of the mixture into a second lipid phase with reduced chloride content and an aqueous phase. In step C, the phase separation into a lipid phase and an aqueous phase then takes place. This phase separation can be carried out centrifugally, e.g., using a disc centrifuge or a decanter centrifuge.

[0014] Citric acid can also be used as a bleaching agent. Therefore, the process does not involve the addition of a base or a bleaching agent to the first lipid phase, the second lipid phase, or the mixture. Logically following the process steps, this means that the organic acid already mentioned in step B cannot be described as an "additional bleaching agent."

[0015] It has surprisingly been shown that, due to the interplay of the aforementioned process parameters and the residence time, a significant reduction in the chloride content in the fat or oil, preferably to a total chloride content below 2 mg / kg, can be achieved.

[0016] Advantageous embodiments of the process are the subject of the dependent claims.

[0017] It is advantageous if the lipid phase comprises one or more animal fats and / or edible oils and preferably so-called UCO, or is formed as such. UCO, or used cooking oil, is a waste product of the food industry. Further processing by hydrolysis is advantageous for ecological and economic reasons.

[0018] Furthermore, it is advantageous if the addition in step B includes the addition of a demulsifier. The demulsifier prevents emulsion formation under the aforementioned process conditions. The small quantity of demulsifier, a maximum of 1000 mg / kg, allows for relatively simple disposal of the resulting aqueous phase.

[0019] Furthermore, it is advantageous, among other things for the disposal of the resulting aqueous phases and to avoid excessively high ion concentrations, if no further ingredients are added to the mixture.

[0020] In particular, if the starting material has a very high total chloride content of more than 200 mg / kg with a similarly high proportion of inorganic chlorides, a special sequence of process steps is recommended for providing the lipid phase in step A.

[0021] A1 Providing a crude oil or crude fat, preferably with a total chloride content of more than 200 mg / kg,

[0022] A2 Addition of demineralized water, organic acid and preferably demulsifier and holding this mixture at a temperature below 100°C, preferably below 80°C, at a process pressure of less than 5 bar, preferably for a residence time of between 30 seconds and 30 minutes, and

[0023] A3 Phase separation of the mixture into a lipid phase with a total chloride content of less than 200 mg / kg and into an aqueous phase.

[0024] The process for the aforementioned starting materials is therefore carried out as a two-stage washing process, wherein the first stage comprises a known acid degreaser with steps A1-A3, and the second stage is a hot washing process with steps AC at higher pressures and longer residence times. Phase separation after each washing can be carried out in a single stage or, preferably, in multiple stages.

[0025] It is particularly noteworthy that the substances added in the first stage of the washing process, which are later found in the resulting water phase of the first stage, are the same as in the second stage, i.e., the hot washing.

[0026] It is advantageous to collect and dispose of the separated water phases from the first washing (stages A1-A3) and the second washing (stages AC) together.

[0027] The acid in step B and / or step A1 is an organic acid, i.e., a carboxylic acid. Formic acid or other acids can be used. Particularly good results have been found with citric acid.

[0028] The concentration of demineralized water in the mixture in step B should ideally be no more than 10% by weight. This keeps the amount of process water produced and requiring treatment comparatively low. The concentration of citric acid in the mixture in step B can be no more than 0.5% by weight.

[0029] Furthermore, the concentration of demulsifier in the mixture in step B can be a maximum of 1000 mg / kg. Overall, the salt concentration in the process water is not excessively high, so disposal of the process water is straightforward. At the same time, the aforementioned concentration already demonstrates a particularly good result for dissolving an emulsion under these reaction conditions and with these reactants.

[0030] Particularly optimized results are achieved with a process pressure in step B in the range of 12-15 bar.

[0031] The residence time under the process conditions in step B can advantageously be more than 3 h, preferably at least 3.5 h. However, no significant changes in the concentration of the products and reactants could be observed after 6 h. Therefore, an advantageous upper limit for the residence time can be 6 h.

[0032] Holding the mixture in step B refers to maintaining the specified process conditions. The mixture does not need to be static; rather, it can be continuously stirred during step B. Stirring can advantageously be continuous. A mixer or agitator, particularly a dynamic mixer, is used, preferably at a stirring speed of 25–125 rpm. Above this speed, the tendency to form an emulsion is significantly increased.

[0033] The separation can be carried out in the form of centrifugal separation using a disc separator and / or a decanter centrifuge.

[0034] Particularly advantageously, the process according to the invention allows for a chloride content of less than 2 mg / kg in the lipid phase provided in step C. This target value is desirable for trouble-free further processing of the lipid phase.

[0035] The process can particularly preferably be implemented as a continuous process. In this case, steps AC, apart from a cooling phase between steps B and C, preferably follow each other directly. This cooling phase is carried out such that the separation in step C takes place at atmospheric pressure and less than 100°C, preferably less than 60°C.

[0036] Furthermore, according to the invention, a method for the hydrolysis of an oil or fat comprises the following steps: 1.1. Providing an oil or fat as the lipid phase with reduced chloride content as a product of the method according to the invention, and 1.2. Adding water to the oil or fat and hydrolyzing the oil or fat for the purpose of hydrolysis, e.g., for the conversion of double bonds or the like.

[0037] The inventive method is explained in more detail below using a specific embodiment and with the aid of the accompanying figures. These show:

[0038] Fig. 1 shows a flowchart of a process scheme as an embodiment of a method according to the invention; and

[0039] Fig. 2 Table with test results.

[0040] The following describes an embodiment of a process according to the invention for reducing the chloride content in fats and / or oils. The aim is to reduce the total chloride content of the oils or fats before hydrolysis to below 2 mg / kg, including both inorganic and organic compounds.

[0041] In a first step 101 of the process according to the invention, an oil or fat 1, for example a cooking oil or an animal fat, is provided. The chloride content of these oils or fats is typically above 300 mg / kg and can be up to 700 mg / kg. Preferably used oils in the process are used cooking oils, so-called UCOs (used cooking oils). These typically contain both organic and inorganic chlorides. The latter are formed by the addition of sodium chloride (NaCl) and potassium chloride, for example, during food preparation and / or subsequent cleaning.

[0042] The proportion of inorganic chlorides in UCO can reach up to 700 mg / kg. The proportion of organic chlorides can reach up to 80 mg / kg. Unlike inorganic chlorides, washing with an aqueous medium has little effect on the removal of these species. The chlorides are partially bound to the fats and edible oils, so their solubility in water is extremely low.

[0043] In a second step, the proportion of water-soluble chlorides, particularly inorganic chlorides, is reduced by acid degumming. The raw material, oils and / or fats, is heated to a temperature below 100°C, and 2% to 5% by weight of demineralized water, based on the crude oil content, is added. Mixing can be carried out using a static or dynamic mixer and / or a stirring vessel.

[0044] The contact time with the demineralized water is between 30 seconds and 30 minutes. The process pressure corresponds to the pump pressure used for conveying the medium. It can advantageously have an overpressure of at least 0.5 bar, but can also be up to 4 bar overpressure. Furthermore, an organic acid or a carboxylic acid is added, with citric acid having yielded particularly good results. Formic acid or other organic acids are also known for this application; however, citric acid is possibly particularly suitable for washing due to the multiple acid groups of the carboxylic acid. The addition of citric acid can be up to 0.35 wt%, based on 100% citric acid. The addition can also be diluted, whereby the proportion of water in the mixture preferably does not exceed 5 wt%.

[0045] Furthermore, the aqueous solution used to wash the fat or oil contains a demulsifier 3, preferably a surfactant. The addition of demulsifier can be up to 250 mg / kg based on the crude oil.

[0046] The temperature of the water / fat or oil mixture 4 during this first washing in the second step 102 is preferably less than 80°C, preferably 20-60°C. The duration of the washing, i.e., the mixing, before the subsequent phase separation is at least 30 min, preferably 1-3 hours.

[0047] In a third step 103, during the first washing process, a centrifugal phase separation takes place between the lipid phase 5 (light phase) and the aqueous phase 6 (heavy phase). Centrifugal phase separation is performed when the mass reaches at least 3000 g. In this step 103, the centrifugal phase separation is achieved by passing the water / fat or oil mixture 4 through a centrifuge 7.

[0048] In centrifugal phase separation 103, a high-performance centrifuge with a g-number of up to 10,000g can be used to separate the oil or fat from the insoluble and soluble substances, such as inorganic chlorides, in the aqueous phase.

[0049] Centrifugal phase separation is achieved using one or more disc centrifuges or decanter centrifuges to separate the purified oil and / or fat from the aqueous phase. The aqueous phase contains a large proportion of inorganic chlorides, citric acid, and insoluble particles.

[0050] In this stage, the inorganic chloride content is reduced to below 200 mg / kg before the next process step. If the inorganic chloride content in the raw material is less than 200 mg / kg, the raw material can proceed directly to the next process step.

[0051] In a fourth step 104, a mixture of demineralized water 9, citric acid 10 and demulsifier 1 1 is added in a dynamic mixer to treat the fat and / or oil of the lipid phase 5 at a temperature below 100°C.

[0052] The preferred proportion of water 9, based on the amount of fat or oil used or of lipid phase 5 used, is a maximum of 10 wt.%.

[0053] The preferred proportion of citric acid 10, based on the amount of fat or oil used or of lipid phase 5 used, is a maximum of 0.5 wt.%.

[0054] The preferred proportion of demulsifier 11, based on the amount of fat or oil used or of lipid phase 5 used, is a maximum of 1000 mg / kg.

[0055] In a fifth step 105, the mixture 12 is then maintained at a temperature above 140°C, preferably up to 195°C, with the process pressure kept constant between 12 bar and 15 bar gauge pressure. This can advantageously be achieved by pressure control. After a preferred residence time of more than 2 h, preferably more than 3 h, particularly preferably 4 h ± 0.5 h, and preferably with continuous stirring at a speed of 25–125 rpm, the mixture is cooled to a temperature below 100°C in a sixth step 106.

[0056] Finally, in a seventh step 107, separation or phase separation takes place using a centrifuge, preferably a disc centrifuge 15, into a heavy phase 13 and a light phase 14. The heavy phase contains water and chlorides, while the light phase contains the purified fat and oil with a total chloride content of less than 2 mg / kg.

[0057] One advantage of this process, for example compared to US9045698B2, WO2022144769A1 and WO2023187628A2, is that no base is used and therefore less oil loss occurs due to saponification of oil with base (or alkali).

[0058] One advantage of this process compared to application CN105368580A is that it does not use electrostatic desalination, but instead employs at least one or more self-emptying centrifuges or decanters for phase separation. This purification of the raw material not only removes soluble chlorides, but also other impurities such as insoluble particles and phosphorus from the respective oil or grease. These impurities, in relation to the aforementioned prior art, cause electrostatic desalination to result in significant fouling and thus a reduced service life.

[0059] A further advantage of the process according to the invention compared to application WO202474759A1 is that the temperature remains below 200°C throughout the entire process. This has the advantage, among others, that the lower heating temperature results in less fouling and thus enables a longer service life. In this case, fouling refers to the contamination of a heat exchanger, e.g., by insoluble particles. Another advantage is that lower process pressure is used, a maximum of 15 bar overpressure, which reduces the design effort required for implementing a corresponding processing plant.

[0060] One advantage of this process compared to FI-130348B, WO2023126478A1, and US2023 / 0287295A1 is that no bleaching step is used. Bleaching requires special bleaching earth, which leads to higher operating costs due to acquisition, disposal, and additional oil losses.

[0061] As shown in the table in Fig. 2, the total chloride content is reduced to less than 2 mg / kg after the second washing step when a residence time of more than 2 h, a temperature of 190°C, and an overpressure of 15 bar are used. The guideline for the respective measurement method is given in the table. “Step 1” in Fig. 2 refers to the chloride content in the lipid phase 5 after step 103, whereas the results under “Step 2” in Fig. 2 describe the chloride content of the oil phase of the light phase 14.

[0062] The significant drop in chloride content—especially the proportion of organic chlorides—is surprising and has never been observed before. It only became apparent through experimentally extending the exposure time during tests. Previously, comparable results could only be achieved through the use of bleaching agents, particularly bleaching earth.

[0063] Reference symbol list

[0064] 1 Lipid phase

[0065] 2 Organic Acid

[0066] 3 Demulsifier

[0067] 4. Water / fat or oil mixture

[0068] 5 Lipid phase

[0069] 6 Water phase

[0070] 7 First centrifuge

[0071] 8 Second centrifuge

[0072] 9 Water

[0073] 10 Citric acid

[0074] 11 Demulsifier

[0075] 12 Mixture

[0076] 13 Heavy Phase / Water Phase

[0077] 14 Light phase / Lipid phase

[0078] 15 disc centrifuges

[0079] 101 Providing an oil or fat

[0080] 102 Addition of water and organic acid

[0081] 103 Phase separation

[0082] 104 Treatment of the lipid phase

[0083] 105 Maintaining temperature and pressure

[0084] 106 Cooling

[0085] 107 Phase separation

Claims

Claims 1. Methods for reducing the chloride content in lipids, especially in Oils and fats, characterized by the following steps: A. Providing a first lipid phase (1 or 5) with increased chloride content B Addition (104) of water (9), in particular demineralized water, and an organic acid (10) to the first lipid phase and holding (105) this mixture (12) at a temperature of more than 140°C and less than 200°C and at a pressure of more than 10 bar and less than 16 bar for a residence time of more than 2h; and C Phase separation (107) of the mixture (12) into a second lipid phase (14) with reduced chloride content and an aqueous phase (13), wherein the process does not include the addition of a base or the addition of a bleaching agent to the first lipid phase (5) or the second lipid phase (14) or the mixture (12).

2. Method according to claim 1, characterized in that the lipid phase (1 or 5) comprises one or more animal fats and / or edible oils and preferably so-called UCO or is formed as such.

3. Method according to claim 1 or 2, characterized in that the addition (104) in step B comprises the addition of a demulsifier (11), preferably in the amount of a maximum of 1000 mg / kg.

4. Method according to claim 3, characterized in that no further ingredients are added to the mixture (12) in step B or C.

5. Method according to one of the preceding claims, characterized in that the provision in step A comprises the following steps: A1 Provision (101 ) of a crude oil or a crude fat, preferably with a total chloride content of more than 200 mg / kg, A2 Addition (102) of demineralized water (4), an organic acid (2) and preferably a demulsifier (3) and holding this mixture at a temperature below 100°C, preferably below 80°C, at a process pressure of less than 5 bar, preferably for a residence time of between 30 seconds and 30 minutes, and A3 Phase separation (103) of the mixture (4) into a lipid phase (5) with a total chloride content of less than 200 mg / kg and into an aqueous phase (6).

6. Method according to one of the preceding claims, characterized in that citric acid is used as the organic acid (2, 10) in step B and / or in step A1.

7. Method according to one of the preceding claims, characterized in that the concentration of demineralized water (4) in the mixture (12) in step B is a maximum of 10 wt.%.

8. Method according to one of the preceding claims^ characterized in that the concentration of citric acid (10) in the mixture (12) in step B is a maximum of 0.5 wt.%.

9. Method according to one of the preceding claims, characterized in that the concentration of demulsifier (11 ) in the mixture (12) in step B is a maximum of 1000 mg / kg.

10. Method according to one of the preceding claims, characterized in that the process pressure in step B is 12-15 bar.

11. Method according to one of the preceding claims, characterized in that the residence time under the process conditions in step B is more than 3h, preferably at least 3.5h.

12. Method according to one of the preceding claims, characterized in that, during the maintenance of the process conditions in step B, stirring, in particular continuous stirring, is carried out with a mixer, in particular a dynamic mixer, preferably at a stirring speed of 25-125 rpm.

13. Method according to one of the preceding claims, characterized in that the phase separation (103, 107) in step A3 and step C is carried out in the form of a centrifugal separation using a disc separator and / or a decanter centrifuge.

14. A method according to any one of the preceding claims, characterized in that the chloride content of the lipid phase (14) provided in step C is less than 2 mg / kg.

15. A method according to any one of the preceding claims, characterized in that the method is designed as a continuous process, wherein steps AC, apart from a cooling step (106) between steps B and C, preferably follow each other immediately.

16. A method for the hydrolysis of an oil or fat, wherein the method comprises the following Steps include: 1.

1. Providing an oil or fat as a lipid phase (14) with reduced chloride content according to step C of claim 14 and 1.1.

1. Adding water to the oil or fat and hydrolyzing the oil or fat.

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