CN111635822A

CN111635822A - Oil decolorant recycling method, oil countercurrent decoloring method and system

Info

Publication number: CN111635822A
Application number: CN202010583011.2A
Authority: CN
Inventors: 庞红梅; 鲁成岭; 李晓峰
Original assignee: SHENZHEN YOUDE GREASE ENGINEERING TECHNOLOGY CO LTD
Current assignee: SHENZHEN YOUDE GREASE ENGINEERING TECHNOLOGY CO LTD
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2020-09-08

Abstract

The invention provides a method for recycling an oil decoloring agent, an oil countercurrent decoloring method and an oil countercurrent decoloring system. The oil countercurrent decoloring method comprises the following steps: feeding oil to be decolorized into a pre-decolorization device, mixing the oil to be decolorized with a recovered decolorizer fed into the pre-decolorization device, and performing pre-decolorization treatment; sending the mixture subjected to the pre-decolorization treatment into a first filtering device for first filtering treatment to obtain filter residues and first filtrate, and discharging the filter residues as waste materials; feeding the first filtrate into a secondary decoloring device, mixing the first filtrate with a fresh decoloring agent fed into the secondary decoloring device, and performing secondary decoloring treatment; sending the mixture subjected to the secondary decolorization treatment into a second filtering device for second filtering treatment to obtain filter pulp and second filtrate, and leading out the second filtrate as a decolorized oil finished product; the filter pulp contains the recovered decolorant and is sent into the pre-decoloring device.

Description

Oil decolorant recycling method, oil countercurrent decoloring method and system

Technical Field

The invention belongs to the technical field of edible oil treatment, and particularly relates to an oil decolorant recycling method, an oil countercurrent decoloring method and a system for the oil decolorant recycling method or the oil countercurrent decoloring method.

Background

The adsorption decoloration is an important step in the oil refining process. In China, the used decolorants are mainly clay, attapulgite and the like. In recent years, along with the gradual enhancement of the environmental protection treatment strength of China and the standard management of mineral resources, more severe requirements are put on the treatment mode of the waste decolorizing agent, the purchasing cost of the decolorizing agent gradually rises, and the requirements bring the production cost to oil refining enterprises. In view of the above reasons, domestic grease enterprises continuously optimize the decoloring process to reduce the decoloring process cost.

The adsorption decoloration of grease utilizes the adsorption effect of active and selective decolorants to achieve the aim of removing grease pigment and other impurities. The adsorption is mainly caused by the surface activity of the adsorbent, and the oil and the adsorbent are fully mixed and contacted at a certain time and temperature to finally reach the adsorption balance. It has a functional relationship, which can be referred to as the isothermal adsorption equation by the fisher-delriexle equation:

x/m＝Kcⁿ

in the formula: x-amount of adsorbed component; m represents the amount of the adsorbent; n is a constant;

k is mass transfer coefficient; c-residual concentration of pigment in oil at adsorption equilibrium.

As the concentration of adsorbed components in the oil gradually decreases, the adsorption gradually declines. Thus, an adsorbent whose primary decolorization has reached equilibrium still has a certain decolorization capacity in freshly neutralized oil. According to this principle, it is theoretically possible to have a recycling value, and if the countercurrent decoloring is employed, a remarkable effect can be obtained.

Based on the theory, many domestic enterprises adopt a pre-decolorization-re-decolorization continuous decolorization process (pre-re-decolorization for short) to reduce the consumption of the decolorization process, and the basic principle of the process is that neutralized oil is contacted with a decolorizer filter cake layer after the decolorization is finished, and after secondary adsorption balance is finished, the neutralized oil is mixed with a fresh decolorizer and re-decolorized. The process is characterized in that: one or more blade type filter is/are required to be added, and the neutralized oil enters a decoloring tank to be decolored with fresh decoloring agent only after being temporarily contacted with a filter cake layer. In the process, the contact time of fresh neutralization oil and a filter cake is short, and as the filter cake layer firstly adsorbs soaps, phospholipids and the like with higher polarity, micropores and the surface of a decolorizing agent are filled outside the filter cake layer and are matched with the quantity of impurities. The pressure of the filter is easily and rapidly increased, the filtration rate is reduced, and the continuity of production and processing is reduced. In order to ensure the continuity, the filter plates need to be frequently switched and replaced, which causes difficulties such as increased labor intensity and the like. And the amount of decolorizer that can be saved is limited, but the residual decolorization capacity of the spent decolorizer is still worth reusing as proven. Therefore, how to improve the adsorption decoloring effect and reduce the economic cost on the basis of fully considering the problems of the prior pre-decoloring is a technical problem which is always attempted to be solved in the field.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a recycling method of an oil decoloring agent, an oil countercurrent decoloring method and a corresponding oil countercurrent decoloring system, so as to solve the technical problems of reduced continuity of adsorption decoloring or increased labor intensity in the existing oil adsorption decoloring method.

In order to achieve the above object, in one aspect of the present invention, a method for recycling an oil decolorant is provided. The method for recycling the oil decolorant comprises the following steps:

feeding the fresh decolorizing agent and the pre-decolorized oil material after the pre-decolorization treatment into a secondary decolorizing device, and carrying out secondary decolorization treatment;

sending the mixture subjected to the secondary decolorization treatment into a second filtering device for second filtering treatment to obtain filter pulp and second filtrate, and leading out the second filtrate as a decolorized oil finished product;

sending the filter pulp into a pre-decoloring device, and performing pre-decoloring treatment on the filter pulp and oil to be decolored;

and sending the mixture subjected to the pre-decolorization treatment into a first filtering device for first filtering treatment to obtain filter residues and first filtrate, discharging the filter residues as waste materials, and sending the first filtrate into the secondary decolorization device, wherein the first filtrate is the pre-decolorized oil.

On the other hand, the invention also provides an oil countercurrent decoloring method, which comprises the following steps:

feeding oil to be decolorized into a pre-decolorization device, mixing the oil to be decolorized with a recovered decolorizer fed into the pre-decolorization device, and performing pre-decolorization treatment;

sending the mixture subjected to the pre-decolorization treatment into a first filtering device for first filtering treatment to obtain filter residues and first filtrate, and discharging the filter residues as waste materials;

feeding the first filtrate into a secondary decoloring device, mixing the first filtrate with a fresh decoloring agent fed into the secondary decoloring device, and performing secondary decoloring treatment;

sending the mixture subjected to the secondary decolorization treatment into a second filtering device for second filtering treatment to obtain filter pulp and second filtrate, and leading out the second filtrate as a decolorized oil finished product; the filter pulp contains the recovered decolorant and is sent into the pre-decoloring device.

Correspondingly, the invention also provides an oil countercurrent decoloring system, which comprises:

the pre-decoloring device is provided with a first oil inlet, a first oil outlet and a recycled decoloring agent inlet;

the first filtering device is provided with a first filtering device oil inlet and a first filtrate outlet, and the first filtering device oil inlet is communicated with the first oil outlet;

the secondary decolorization device is provided with a second oil inlet and a second oil outlet, and the second oil inlet is communicated with the first filtrate outlet; a fresh decolorant adding inlet is also arranged on the secondary decoloration device or a pipeline for communicating the second oil material inlet with the first filtrate outlet;

and the second filtering device is provided with a second filtering device oil inlet and a filtering slurry outlet, the second filtering device oil inlet is communicated with the second oil outlet, and the filtering slurry outlet is communicated with the recycling decolorant inlet.

Compared with the prior art, the method for recycling the oil decolorant and the method for countercurrent decoloring the oil are that the fresh decolorant and the oil to be decolored are set to flow in opposite directions, and the used recycled decolorant is led into the pre-decoloring device, so that the oil to be decolored is subjected to pre-decoloring treatment, and the residual decoloring capacity of the recycled decolorant is fully utilized. And the recovery of the decoloring agent can be flexibly controlled, and the addition amount of the fresh decoloring agent can be flexibly controlled according to the residual decoloring capacity of the recovered decoloring agent, so that the decoloring effect of the oil material can be effectively controlled. The decoloring agent can be effectively recycled, so that the purpose of saving the using amount of the decoloring agent is realized, the decoloring cost of the oil is effectively reduced, the discharge amount of the decoloring agent is reduced, and the environmental protection is improved. In addition, the method has simple process steps and easily controlled conditions, and can effectively ensure the stability of the decoloring treatment effect and the filtering effect, thereby effectively improving the stability of the performance of the oil product and reducing the labor intensity.

According to the oil countercurrent decoloring system, the pre-decoloring device, the first filtering device, the secondary decoloring device and the second filtering device are sequentially communicated to form a circulating decoloring oil way for recycling the decoloring agent, and a reverse flowing oil way for the fresh decoloring agent and the oil to be decolored is realized, so that the decoloring effect of the oil is effectively improved, the using amount of the fresh decoloring agent is remarkably saved, the cost of oil decoloring treatment is reduced, the discharge of waste decoloring agent is reduced, and the environmental protection is improved.

Drawings

FIG. 1 is a schematic diagram illustrating the principle of the oil decolorizer recycling and oil countercurrent decolorization method according to the embodiment of the present invention;

FIG. 2 is a schematic process flow diagram of a method for recycling an oil decolorant according to an embodiment of the present invention;

FIG. 3 is a schematic process flow diagram of a countercurrent decolorization method for oil according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an oil countercurrent decoloring system according to an embodiment of the invention;

FIG. 5 is a graph showing the comparison of the amount of soap contained in oil before neutralization of oil by the process of the oil countercurrent decoloring method of example 1 of the present invention and the conventional decoloring method;

FIG. 6 is a graph showing the comparison of the phosphorus content in the oil before neutralization of the oil by the countercurrent oil decoloring process and the conventional decoloring process in example 1;

FIG. 7 is a comparison graph of the color of oil before neutralization in the process of oil counter-current decolorization method in example 1 of the present invention and the process of conventional decolorization method.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In order to overcome the defects of the conventional decolorizer recovery method in the background art, the embodiment of the invention provides an oil decolorizer recovery method and an oil countercurrent decolorization method, which can effectively recover and utilize the decolorizer and simultaneously can effectively control the decolorization effect of oil. The principle of the oil decolorant recycling method and the oil countercurrent decoloring method is shown in figure 1. The fresh decolorant and the oil to be decolored are set to flow in reverse directions, so that on one hand, the residual decoloration capacity of the recovered decolorant is fully utilized; on the other hand, the addition amount of the fresh decolorizing agent can be flexibly controlled according to the residual decolorizing capacity of the recovered decolorizing agent, so that the decolorizing effect of the oil can be effectively controlled, and the decolorizing process cost is reduced.

Based on the principle shown in fig. 1, in one aspect, the embodiment of the invention provides a method for recycling an oil decolorant. In order to better illustrate the method for recycling the oil decolorant according to the embodiment of the present invention, the method for recycling the oil decolorant according to the embodiment of the present invention is described below with reference to the apparatus shown in fig. 4, but it should be understood that the method for recycling the oil decolorant according to the embodiment of the present invention is not limited to the apparatus shown in fig. 4. The technological process of the oil decolorant recycling method is shown in figure 2, and comprises the following steps:

s01: feeding the fresh decolorizing agent and the pre-decolorized oil material after the pre-decolorization treatment into a secondary decolorizing device 3, and carrying out secondary decolorization treatment;

s02: sending the mixture subjected to the secondary decolorization treatment into a second filtering device 4 for second filtering treatment to obtain filter pulp and second filtrate, and leading out the second filtrate as a decolorized oil finished product;

s03: sending the filter pulp into a pre-decoloring device 1, and performing pre-decoloring treatment on the filter pulp and oil to be decolored;

s04: and sending the mixture subjected to the pre-decolorization treatment into a first filtering device 2 for first filtering treatment to obtain filter residues and first filtrate, discharging the filter residues as waste materials, and sending the first filtrate, which is the pre-decolorized oil, into a secondary decolorization device 3.

In step S01, the fresh decolorizer and the pre-decolorized oil are subjected to a secondary decolorization treatment in the secondary decolorization device 3, so that the pre-decolorized oil is subjected to a secondary decolorization treatment again, thereby meeting the requirements of the oil finished product. After the secondary decoloring treatment is finished, introducing the mixture subjected to the secondary decoloring treatment into step S02 for subsequent treatment. And judging the standard of finishing the secondary decolorization treatment can be directly carried out according to the standard of the finished oil products.

In one embodiment, the fresh decolorizer can be mixed with the oil to be decolorized before being sent to the secondary decolorization device 3. Specifically, as shown in fig. 4, the fresh decolorizer and the oil to be decolorized are mixed in the pre-mixer 3' before being transported to the secondary decolorization device 3.

In addition, the conditions of the secondary decoloring treatment may be those of a conventional decoloring treatment, and specifically, the decoloring treatment process conditions of the decoloring treatment may be referred to in the following examples. In one embodiment, the temperature of the secondary color treatment is 90-150 ℃, and the vacuum degree in the secondary decoloring device during the secondary color treatment is 1-40 kPa. By combining the process of the recycling method of the oil decoloring agent in the embodiment of the invention, the conditions of the secondary decoloring treatment are optimized, the decoloring effect can be effectively improved, the consumption of the decoloring agent is saved, and the economic cost is reduced. The temperature of the secondary decoloring may be controlled by introducing steam into the secondary decoloring apparatus 3.

In one embodiment, the secondary decoloring device 3 may be a decoloring tower, or may be a decoloring device having the same function.

The fresh decolorant can be a decolorant commonly used in an oil decoloring process. In one embodiment, the fresh decolorizing agent can be at least one of clay, attapulgite, activated carbon, and the like. In a specific embodiment, the fresh decolorant can be a mixed decolorant of clay and attapulgite according to a ratio of 2: 1.

In the step S02, the mixture after the secondary decolorization is subjected to the second filtration treatment in the second filtration device 4 to obtain a filtrate and a second filtrate, that is, the decolorizer after the secondary decolorization in the step S01 is separated from the decolorized finished oil product. Wherein the filtered pulp contains the decolorant after the secondary decoloration treatment, namely the decolorant used in the step S01 is recovered and collected; the second filtrate is the finished decolorized oil product meeting the requirements of the finished decolorized oil product. The second filtrate can be introduced into a buffer tank for decolorization of the finished oil product process as shown in fig. 4.

In one embodiment, the second filter device 4 is a pulse filter device. In order to improve the filtering effect and efficiency, the number of the pulse filtering devices is at least one, and when the number of the pulse filtering devices is multiple, the pulse filtering devices can be controlled to intermittently work or alternately work or simultaneously work in actual production. A pulse filtering device is chosen as said second filtering device 4, because it is as follows:

1) the functions of oil inlet, circulation, filtration, evacuation, extrusion and oil discharge (optional) are the same as those of other conventional filtration devices, but the other conventional filtration devices adopt a blade type design, and the pulse filtration device adopts a tubular type design; 2) the conventional other filtering devices such as blade or plate-frame filtering devices can perform extrusion drying through gas after filtering is finished, liquid in a filter cake is extruded and discharged, vibration is needed in the slag discharging process after extrusion drying, noise is generated, a plate is easy to damage, slag discharging is not clean, a discharging pipeline or a slag discharging valve is blocked, and if non-dried filtered slurry is discharged, the problem that the pipeline is blocked due to unsmooth slurry discharging is difficult to occur; the pulse filtering device adopts a tubular design, filter residues or filter pulp are discharged through gas or liquid back flushing, the back flushing function is easy to realize in the tubular filtering device, and the sequential slag discharge and the one-time slag discharge can be selected; if the conventional blade filtering device or the like is used, the conventional blade filtering device or the like is not easy to realize, because the reverse blowing of the filtering device can cause the deformation of the blades or the damage of a filtering medium, and only one-time slag discharging operation can be realized; 3) the conventional blade type filtering device needs to be circularly operated when filtering, filtrate can be normally discharged after being transparent, and a filtering medium of the pulse filtering device is filter cloth, so that transparent filtrate can be normally discharged without circular operation; 4) conventionally, for example, the filtering medium of a blade type filtering device is a metal wire mesh, and after the blade type filtering device operates for a period of time, a decoloring agent is easy to block the wire mesh, so that the filtering speed is reduced, at the moment, the plate needs to be cleaned by hot alkali, and the pulse filtering device only needs to clean or replace a filter bag.

Due to the technical design of the recycling method of the oil decolorant in the embodiment of the invention, the pulse filtering device is preferably used as the second filtering device 4, so that the used decolorant can be efficiently filtered, if the grease in the decolorant is discharged without extrusion drying, the decolorant layer is directly discharged and collected in a filtered pulp form through back flushing, more importantly, the residual decoloring capacity of the recycled decolorant is effectively reserved, and the obtained filtered pulp can be conveyed to a temporary storage tank or directly conveyed to the pre-decoloring device in the step S03 for recycling. It is detected that compared with the prior art, the filter pulp contains a large amount of decolorized oil finished products, and the decolorized oil finished products in the filter pulp can account for 5-90%, such as 60-80% by weight. In a specific embodiment, the second filtering device 4 may be a plurality of devices, such as 3 devices, arranged in parallel to realize simultaneous filtering or alternate filtering, as shown in fig. 4, so as to improve the filtering efficiency.

Therefore, in an embodiment, the second filtering device 4 is a pulse filtering device, after the second filtering process is performed and the second filtrate is led out, nitrogen and/or oil to be decolorized is introduced into the second filtering device 4 for reverse blowing, and the filtered slurry is blown out and sent into the pre-decolorizing device 1.

In the step S03, the filtered slurry containing the recovered decolorizer is sent to the pre-decolorizing device 1 and then is pre-decolorized with the oil to be decolorized, so that the residual decolorizing capacity of the recovered decolorizer can be fully utilized, and the oil to be decolorized is pre-decolorized. In one embodiment, the pre-decoloring treatment is performed on the filter pulp and the oil to be decolored in the pre-decoloring device according to a mass ratio of 0.5 to 20%. In another embodiment, the temperature of the pre-decoloring treatment is 90 ℃ to 150 ℃, and the vacuum degree in the pre-decoloring device 1 during the pre-decoloring treatment is 1kPa to 40 kPa. By optimizing the use amounts of the filter pulp and the oil to be decolorized and controlling and optimizing the pre-decolorization treatment conditions, the residual decolorization capacity of the recovered decolorizer can be fully exerted, so that the purpose of fully utilizing the recovered decolorizer is realized, and the addition amount of the fresh decolorizer in the step S01 is reduced. In addition, the fresh decolorant required to be added can be accurately calculated and controlled by detecting the related indexes of the mixture after the pre-decoloration treatment. And the temperature of the secondary decoloring treatment can be realized by introducing steam into the pre-decoloring apparatus 1.

In one embodiment, the feeding of the filtered slurry into the pre-bleaching apparatus 1 is carried out by a second transfer pump 52 as shown in fig. 4, the second transfer pump 52 being provided on a pipe for transferring the filtered slurry.

In an embodiment, the pre-decoloring device 1 may be a decoloring tower, and may be a decoloring device having the same function.

In addition, the oil to be decolorized may be any oil that enters a decolorization process stage and needs decolorization treatment, or oil that needs decolorization treatment, particularly edible oil, as in another embodiment, the oil to be decolorized includes any one of neutralized oil of grease, fatty acid methyl ester, fatty alcohol, and fatty amine. In a particular embodiment, the oil to be decolorized is, for example, neutralized soybean oil.

In the step S04, the decolorant recovered in the step S02 is reused in the step S03. Therefore, the decolorant recovered and reused from the mixture after the pre-decoloration treatment basically has no residual decolorant capability, so that filter residue and first filtrate are obtained after the first filtration treatment, wherein the filter residue is a waste decolorant containing no decolorant capability and can be discharged as waste. And the first filtrate, that is, the pre-decolorized oil in step S01, is collected and introduced into the secondary decolorization device 2 in step S01 to be subjected to the secondary decolorization treatment, that is, the final decolorization treatment of the oil to be decolorized in step S03.

In an embodiment, the first filtering device 2 may be at least one of a pulse filtering device and a blade filtering device. The number is at least one. The number of the first filtering devices 2 is at least one for the filtering effect and the efficiency, and when the number of the first filtering devices 2 is multiple, the first filtering devices 2 can be controlled to work intermittently, alternatively or simultaneously in the actual production. Through detection, when the first filter 2 is a blade filter, the obtained filter residue contains about 18-22 wt% of oil-containing oil, and the rest is waste decolorant filter residue.

Therefore, in the above embodiments, the method for recycling the oil decoloring agent sets the fresh decoloring agent and the oil to be decolored to flow in opposite directions, can introduce the recycled decoloring agent into the pre-decoloring device 1 to fully utilize the residual decoloring capacity of the recycled decoloring agent, can flexibly control the recycling of the decoloring agent, and can control and adjust the addition amount of the fresh decoloring agent according to the residual decoloring capacity of the recycled decoloring agent, thereby effectively controlling the decoloring effect of the oil. Therefore, the method for recycling the oil decoloring agent in the embodiments can save the consumption of the decoloring agent, effectively reduce the cost of oil decoloring, reduce the discharge of waste decoloring agent and improve the environmental protection. In addition, the recycling method has simple process steps and easily-controlled conditions, and can effectively ensure the stability of the decoloring treatment effect and the filtering effect, thereby effectively improving the stability of the performance of the decolored oil product.

The decolorant used in the recycling method in the above embodiments belongs to a polar adsorbent, has good selectivity, and is very easy to adsorb polar impurities. In the oil decolorant recycling process or the countercurrent decoloring process, the decolorant used once, namely the filtrate containing the decolorant recovered by the second filtering device 4 is firstly mixed with the oil to be decolored, such as fresh neutralized dry oil, and the residual decoloring activity of the decolorant is utilized to firstly adsorb soap, phospholipid, trace metals, polycyclic aromatic hydrocarbon with larger molecular weight and pesticide residues in the oil to be decolored, and the residual activity of the decolorant can adsorb partial pigments and other impurities. The pre-decolorized oil (clear oil) is mixed with a fresh decolorizer for the second decolorization adsorption, so that a new isothermal adsorption balance is established, and the activity of the fresh decolorizer can be fully exerted.

Meanwhile, the oil decolorant recycling process or the countercurrent decoloring process recycles the filtering slurry containing the decolorant formed by the second filtering treatment of the second filtering device 4, the filtering slurry is uniformly mixed with the oil to be decolored, the oil decolorant is subjected to adsorption pre-decoloring treatment for a period of time, and then the oil decolorant is removed to the first filtering device 2 for first filtering treatment, and the time of fully mixing and adsorbing is provided by establishing two times of adsorption and filter pressing decoloring, so that the decoloring effect is improved. Learn according to the actual chemical examination index of production, through after the preliminary decoloration treatment, the preliminary decoloration oil residual soap after the preliminary decoloration treatment reduces to 0, the phosphorus reduces to below 2ppm (or lower), equivalent adsorbent adsorbs polarity impurity also is equivalent promptly, when through first filter equipment 2 like the leaf filter, polarity impurity is few and distribute evenly on the filter cake layer, can avoid the decline of first filter equipment 2's filtration rate, reach continuous stable large-scale production better, and the intensity of labour has been reduced, avoided current decoloration technology need frequently switch over and change the difficult problems such as the filter plate causes intensity of labour increase, effectively reduce.

On the other hand, also based on the principle shown in fig. 1, the embodiment of the invention also provides a method for counter-current decolorization of oil. In order to better illustrate the oil countercurrent decoloring method of the embodiment of the invention, the oil countercurrent decoloring method of the embodiment of the invention is described in the following with reference to the device shown in fig. 4, but it should be understood that the oil countercurrent decoloring method of the embodiment of the invention is not limited to the device shown in fig. 4. The technological process of the oil countercurrent decoloring method is shown in figure 3 and comprises the following steps:

s05: feeding oil to be decolorized into a pre-decolorization device 1, and carrying out pre-decolorization treatment on the oil to be decolorized and a recovered decolorizer fed into the pre-decolorization device 1;

s06: sending the mixture subjected to the pre-decolorization treatment into a first filtering device 2 for first filtering treatment to obtain filter residues and first filtrate, and discharging the filter residues as waste materials;

s07: feeding the first filtrate into a secondary decoloring device 3, mixing the first filtrate with a fresh decoloring agent fed into the secondary decoloring device 3, and performing secondary decoloring treatment;

s08: sending the mixture subjected to the secondary decolorization treatment into a second filtering device 4 for second filtering treatment to obtain filter pulp and second filtrate, and leading out the second filtrate as a decolorized oil finished product; the filtrate slurry contains the recovered decolorizer and is sent to the pre-decolorization device 1.

Since the above method for recycling the oil decolorant as shown in fig. 2 is expressed based on the angle of the order of the decolorant recycling and the successive treatment, the method for the countercurrent decolorization of the oil is expressed based on the angle of the order of the decolorization treatment and the successive treatment of the oil to be decolorized. Therefore, the step S05 corresponds to the step S03, the step S06 corresponds to the step S04, the step S07 corresponds to the step S01, and the step S08 corresponds to the step S02, so that the process steps and conditions of the steps S05 to S08 are not repeated again for saving the description of the present invention.

Similarly, in the above embodiments, the method for recycling the oil decoloring agent sets the fresh decoloring agent and the oil to be decolored to flow in opposite directions, can introduce the recycled decoloring agent into the pre-decoloring device 1 to fully utilize the residual decoloring capacity of the recycled decoloring agent, can flexibly control the recycling of the decoloring agent, and can control and adjust the addition amount of the fresh decoloring agent according to the residual decoloring capacity of the recycled decoloring agent, thereby effectively controlling the decoloring effect of the oil. Therefore, the oil countercurrent decoloring method in the embodiments can save the consumption of the decoloring agent, effectively reduce the decoloring cost of the oil, reduce the discharge amount of the waste decoloring agent and improve the environmental protection. In addition, the oil countercurrent decoloring method has simple process steps and easily controlled conditions, and can effectively ensure the stability of the decoloring treatment effect and the filtering effect, thereby effectively improving the stability of the performance of the decolored oil product.

Based on the recycling method of the oil decolorant and the oil countercurrent decoloring method, the embodiment of the invention also provides an oil countercurrent decoloring system for realizing the recycling method of the oil decolorant or the oil countercurrent decoloring method. The oil countercurrent decoloring system is shown in fig. 4, and comprises a pre-decoloring device 1, a first filtering device 2, a secondary decoloring device 3 and a second filtering device 4, wherein the pre-decoloring device 1, the first filtering device 2, the secondary decoloring device 3 and the second filtering device 4 are communicated into a whole through a conveying pipeline.

The pre-decoloring device 1 is provided with a first oil inlet 11, a first oil outlet 12 and a recycled decoloring agent inlet 13. Therefore, the pre-decoloring device 1 is used for pre-decoloring the oil to be decolored and the filter pulp containing the recycled decoloring agent and fed by the second filtering device 4, so as to pre-decolor the oil to be decolored. Both the above-described step S03 and step S05 are performed in the preliminary decoloring apparatus 1.

The oil to be decolorized may be any oil requiring decolorization treatment, particularly an edible oil such as soybean oil or the like, as described above.

The first filter device 2 is constructed as shown in fig. 4, and is provided with a first filter device oil inlet 21, a first filtrate outlet 22, and a residue discharge port 23. Wherein, the first filtering device oil inlet 21 is communicated with the first oil outlet 12 of the pre-decoloring device 1. The first filter device 2 may be at least one of the pulse filter device and the blade filter device, and the number of the first filter devices is at least one. In an embodiment, as shown in fig. 4, the first filtering device 2 is composed of 4 blade filtering devices arranged in parallel, and each first filtering device oil inlet 21 of the 4 blade filtering devices 2 is respectively communicated with the first oil outlet 12 of the pre-decoloring device 1; each first filtrate outlet 22 is used for leading out the first filtrate filtered by each first filtering device 2 and generated by the first filtering treatment; the residue discharge ports 23 are used to discharge the residue containing the waste decolorizer generated by the first filtration process in the first filtration device 2 as waste. In a further embodiment, a first delivery pump 51 is further disposed on a pipeline connecting the first oil inlet 21 and the first oil outlet 12, so as to effectively introduce the pre-decolorized mixture discharged from the pre-decolorization device 1 into the first filtration device 2 for the first filtration treatment. Therefore, the connection relationship between the first filtering device 2 and other devices can effectively filter the mixture which is sent by the pre-decoloring device 1 and is subjected to the pre-decoloring treatment, and filter residues which are separated are also used as a waste decoloring agent and first filtrate which is also used as pre-decolored oil. Both the above-described step S04 and step S06 are performed in the first filter device 2.

The secondary decolorization device 3 is provided with a second oil inlet 31 and a second oil outlet 32. Wherein the second oil inlet 31 is communicated with the first filtrate outlet 22 of the first filtering device 2; the second oil outlet 32 is used for guiding the decolorized oil decolorized by the secondary decolorization device 3 out to the second filtration device 4. Therefore, the secondary decolorization device 3 is configured to perform the secondary decolorization treatment on the first filtrate fed from the first filtration device 2, i.e. the pre-decolorized oil, so that the decolorized oil is treated to meet the requirements of the finished decolorized oil. Both of the above-described step S01 and step S07 are performed in the secondary decoloring apparatus 3.

In addition, the secondary decoloring device 3 may also be directly provided with a fresh decoloring agent feeding port or a fresh decoloring agent feeding port is further provided on a pipeline through which the second oil inlet 31 is communicated with the first filtrate outlet 22, so as to add a fresh decoloring agent into the secondary decoloring device 3, so that the fresh decoloring agent is mixed with the introduced first filtrate, and the secondary decoloring treatment is performed. In one embodiment, as shown in fig. 4, the oil countercurrent decoloring system further includes a premixing device 3 'having a premixed oil inlet 31' and a premixed oil outlet 32 ', and a fresh decoloring agent feeding port 33'. At this time, the premixed oil inlet 31 ' of the premixing device 3 ' communicates with the first filtrate outlet 22 of the first filtering device 2, and the premixed oil outlet 32 ' communicates with the second oil inlet 31 of the secondary decoloring device 3. In this way, the first filtrate led out through the first filtrate outlet 22 and the fresh decolorizer added through the fresh decolorizer feeding port 33 ' are premixed in the premixing device 3 ', and then introduced into the secondary decolorization device 3 through the premixed oil outlet 32 ' to be subjected to secondary decolorization.

The second filter unit 4 is provided with a second filter unit oil inlet 41, a second filtrate outlet 42 and a filtrate outlet 43, as shown in fig. 4. The second filtering device oil inlet 41 is communicated with the second oil outlet 32 of the secondary decoloring device 3, so that the mixture after the secondary decoloring treatment in the secondary decoloring device 3 is sent to the second filtering device 4 for the second filtering treatment; the filtered pulp outlet 43 is communicated with the recycled decolorizer inlet 13 of the pre-decolorization device 1, and is used for recycling the decolorizer used in the secondary decolorization device 3 and sending the decolorizer into the pre-decolorization device 1 for reuse. Wherein the second filtering device 4 is a pulse filtering device as described above, and the number of the pulse filtering devices is at least one. In an embodiment, as shown in fig. 4, the second filtering device 4 is composed of 3 pulse filtering devices arranged in parallel, wherein each second filtering device oil inlet 41 of the 3 pulse filtering devices 4 is respectively communicated with the second oil outlet 32 of the secondary decoloring device 3, each second filtrate outlet 42 is respectively used for leading out the second filtrate filtered by each second filtering device 4, that is, the finished decolored oil product, and each filtrate outlet 43 is respectively used for discharging the filtrate containing the used decolorant filtered by each second filtering device 4 and sending the filtrate to the pre-decoloring device 1 through the recovered decolorant inlet 13, so that the used decolorant is recovered and reused.

In order to enable the filtered pulp discharged from the filtered pulp discharge port 43 to be flexibly sent to the pre-decoloring device 1 for use, a pulp buffer device 6 is further provided on a pipeline connecting the filtered pulp outlet 43 and the recycled decoloring agent inlet 13 of the pre-decoloring device 1. And guiding the filtered slurry led out by the second filtering device 4 into the slurry caching device 6 through a filtered slurry outlet 43 for caching and collection, and then guiding the filtered slurry into the pre-decoloring device 1 for reuse according to needs.

In a further embodiment, a second delivery pump 52 is further provided on a pipeline connecting the filtered pulp outlet 43 and the recovered decolorizer inlet 13 of the pre-decolorization apparatus 1, preferably on a pipeline connecting the pulp buffer 6 and the recovered decolorizer inlet 13 of the pre-decolorization apparatus 1, for introducing the filtered pulp into the pre-decolorization apparatus 1 and for being provided with delivery power again. Therefore, the connection relationship between the second filtering device 4 and other devices can effectively filter the mixture sent by the secondary decoloring device 3 and subjected to the secondary decoloring treatment, and separate filter pulp, i.e. filter pulp containing used decoloring agent, and second filtrate, i.e. decolored oil product subjected to the secondary decoloring treatment. Both the above-described step S02 and step S08 are performed in the second filtering device 4.

Therefore, the oil countercurrent decoloring system is used for sequentially communicating the pre-decoloring device 1, the first filtering device 2, the secondary decoloring device 3 and the second filtering device 4 to form an oil countercurrent decoloring system or a decoloring agent recycling system, and realizing a reverse flowing circulating oil way for fresh decoloring agent and oil to be decolored, thereby effectively improving the decoloring effect of the oil, remarkably saving the using amount of the fresh decoloring agent, reducing the cost of oil decoloring treatment, reducing the discharge of waste decoloring agent and improving the environmental protection.

The following specific examples are now provided to further illustrate the invention.

The embodiment provides a method for recycling an oil decolorant or a method for decoloring oil by countercurrent flow of oil by using an oil countercurrent flow decoloring system; the structure of the oil countercurrent decoloring system is shown in fig. 4, and specifically the oil countercurrent decoloring system is described above. The steps of the method for recycling the oil decolorant or the method for countercurrent decoloring the oil are both the method for recycling the oil decolorant or the method for countercurrent decoloring the oil.

After the oil decolorant recycling method or the oil countercurrent decoloration method (recorded as countercurrent decoloration) process is successfully debugged, the related data are tracked and analyzed after the current 1000t/d refinery continuously operates for one month, and the related data are compared with the traditional decoloration (the current decoloration before modification is recorded as decoloration before modification).

Oil sources: the main indexes of the soybean oil are shown in the following table 1, and the soybean oil forms the neutralized oil of the oil to be decolorized after pretreatment:

TABLE 1 crude Soybean oil index

Raw materials	Acid value (mgKOH/g)	Containing phosphorus (ppm)	Impurity (%)	Moisture (%)	Peroxide number (mmol/kg)
						Soybean oil	1.62	105	0.01	0.06	2.23

Parameters of the decoloring process are as follows: the decoloring agent is a mixture of argil and attapulgite according to a ratio of 2: 1; decolorizing vacuum about 80mbar, decolorizing temperature 105 ℃; the pre-decoloring device and the secondary decoloring device are both decoloring towers, and the decoloring towers adopt steam stirring; the consumption of a decoloring agent in the traditional decoloring (before modification) process is 15kg/t, and the consumption of a decoloring agent in the oil material decoloring agent recycling method or the oil material countercurrent decoloring method process is 10 kg/t.

The related test results after the oil decolorant recycling method or the oil countercurrent decoloring method are as follows:

and (3) obtaining the decolored oil after the neutralization oil of the oil to be decolored is treated according to the decoloring condition and the decoloring process before modification and the countercurrent decoloring process, wherein the relevant indexes are measured as follows:

a. indexes of neutralized oil and decolored oil:

the results of the measurement of relevant indexes of pre-decolorization and secondary decolorization of the neutralized oil after decolorization by the decolorization process before modification and in the counter-current decolorization process are shown in the following table 2:

TABLE 2 indexes relating to neutralized and bleached oils

Wherein, the data of the decoloration process before modification in the table 2 is according to the usage of 15kg/t decolorant, the data of the countercurrent decoloration process is according to the usage of 10kg/t decolorant, and each inspection index data is a factory measured value. Wherein, the acid value before and after the oil neutralization and decolorization in the two decolorization processes is not changed, but the soap content, the phosphorus content and the color before and after the oil neutralization and decolorization in the two decolorization processes are obviously changed. The soap content before and after the oil decolorization in the two specific decolorization processes is shown in fig. 5, the phosphorus content is shown in fig. 6, and the color is shown in fig. 7.

As can be seen from fig. 5, the soap content in the neutralized oil after the decoloration by the decoloration process before the modification, the pre-decoloration in the counter-current decoloration process, and the secondary decoloration by the counter-current decoloration process is reduced from 50ppm to zero, and the residual soap can be completely removed after the pre-decoloration by the counter-current process, which indicates that the removal effect of the residual soap by the pre-decoloration is relatively obvious, thereby effectively indicating that the recovered decolorant contained in the recovered filter pulp also has decoloration activity.

As can be seen from fig. 6, the pre-decoloring in the counter-current decoloring process has a certain effect, but the effect is not as good as that of the decoloring before modification in the case of a relatively small amount, but the effect is more obvious after the secondary decoloring in the counter-current decoloring process, and even in the case of a small amount of decoloring agent, the effect is better than that of the decoloring before modification.

As can be seen from fig. 7, the effect of the pre-decolorization in the counter-current decolorization process on the removal of the color in the oil is not obvious, but after the secondary decolorization in the counter-current decolorization process, even if the amount of the bleaching clay is small, the color of the decolorized oil is better than that of the decolorized oil in the decolorization process before modification, so that the modification achieves the expected purpose.

b. Decolorization process consumption comparison and analysis

And (3) comparing and analyzing consumption of the pre-decoloring and secondary decoloring processes of the neutralized oil after decoloring by the decoloring process before modification and in the countercurrent decoloring process. The results of the measurement of the consumption related indexes of the pre-decolorization and the secondary decolorization processes of the neutralized oil after the decolorization of the pre-modification decolorization process and the counter-current decolorization process are shown in the following table 3:

TABLE 3 consumption comparison analysis of decolorization process before modification and counter-current decolorization process

Name (R)	Numerical value	Unit of	Remarks for note
				Consumption comparison	1000	t/d	Soybean oil as raw material
Decolorizer saving	5	kg/t	Taking the mean value
				Neutral oil saving	1	kg/t	The waste decolorant contains 18 percent of oil
Decolouring steam savings	2	kg/t	Stir-containing steam/cake-blowing steam comprehensive comparison
				Increase of power consumption	-0.5	kwh/t

As can be seen from Table 3, compared with the decolorization process before reconstruction, the countercurrent decolorization process of the embodiment of the invention saves 2kg/t of steam per ton of oil. Specifically, in the counter-current decoloring process, the consumption of the decoloring agent is reduced, and 5kg/t of the decoloring agent is saved. In addition, the service time of the leaf filter is prolonged to 180 minutes from 120 minutes, the cake blowing times of the four leaf filters are reduced for 16 times, the switching and blowing time is 15 minutes each time, the time is 240 minutes, the steam flow per hour is increased by 800kg, the steam is saved by 3.2t, which is equivalent to 3.2kg/t, and the steam is saved by 2kg/t per ton of oil because the pre-decoloring tower is newly added and the stirring steam is increased by 1.2 kg/t.

As can be seen in Table 3, the loss of neutral oil in the counter-current decolorization process of the embodiment of the present invention is reduced compared to the decolorization process before modification. Specifically, the consumption of the decolorizing agent in the process of the countercurrent decolorizing process is reduced, the loss of the neutral oil brought away by the waste decolorizing agent is reduced, the oil content of the decolorizing agent is saved by 5kg/t and calculated by 18 percent, and the loss of the neutral oil is reduced by 1 kg/t.

Table 3 shows that, compared with the decoloring process before modification, the countercurrent decoloring process according to the embodiment of the present invention has two pumps, one pump is used for conveying grease and the other pump is used for conveying filtered slurry, so that the power consumption is increased by 0.5kwh/t of oil, but the increase of the power consumption does not affect the overall economic benefit.

c. Economic benefit analysis of counter-current decoloring process and decoloring process before modification

Taking a soybean oil refinery with the processing capacity of 1000t/d in the embodiment as an example, the cost that can be saved each year is simply calculated, 300d of start-up all the year, 5500 yuan/t of soybean oil price, 1950 yuan/t of decolorizing agent price, 190 yuan/t of steam price and 0.7 yuan/kwh of electricity price are set, and the following is calculated by combining the data in table 3:

the cost of the decolorizing agent is saved each year: 1,950 × 0.005 × 1,000 × 300 ═ 2,925,000 yuan

Cost savings per year for neutral oils: 5,500 × 0.001 × 1,000 × 300 ═ 1,650,000 yuan

Cost savings per year for steam: 190 × 0.002 × 1,000 × 300 ═ 114,000 yuan

The annual increased cost of electricity: 0.7 × 0.5 × 1,000 × 300 ═ 105,000 yuan

The annual cost is 2,925,000+1,650,000+114,000-

The total investment is about 580 million, so the investment can be recovered in 1.3 years, and the method has great investment value.

The experimental result of the continuous countercurrent decoloring process in the soybean oil refining process of the embodiment shows that the countercurrent decoloring process of the embodiment of the invention has feasible utilization theory and successful practice, can save about 30 percent of decoloring agent, improve the oil yield and the like, reduce pollutant discharge, obtain good social benefit and economic benefit and has popularization significance. The economic efficiency of the method is more obvious for national oil storage with higher decolorant.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A method for recycling an oil decolorant comprises the following steps:

2. The recycling method according to claim 1, characterized in that: the first filtering device is at least one of a pulse filtering device and a blade filtering device, and the number of the first filtering devices is at least one; and/or

The second filtering devices are pulse filtering devices, and the number of the second filtering devices is at least one.

3. The recycling method according to claim 1, characterized in that: and the second filtering device is a pulse filtering device, after the second filtering treatment is carried out and the second filtrate is led out, at least the oil to be decolorized is introduced into the second filtering device for carrying out back flushing treatment, and the filter pulp is blown out and sent into the pre-decolorizing device.

4. The recycling method according to any one of claims 1 to 3, characterized in that: the pre-decoloring treatment is carried out on the filter pulp and the oil to be decolored in the pre-decoloring device according to the mass ratio of 0.5-20%; or/and

the fresh decolorant and the pre-decolored oil are fed into the secondary decoloration device according to the mass ratio of 0.1-15% to carry out secondary decoloration treatment.

5. The recycling method according to any one of claims 1 to 3, characterized in that: the temperature of the pre-decoloring treatment is 90-150 ℃, and the vacuum degree in the pre-decoloring device is 1-40 kPa during the pre-decoloring treatment; or/and

the temperature of the secondary color treatment is 90-150 ℃, and the vacuum degree in the secondary decoloring device is 1-40 kPa during the secondary color treatment.

6. A counter-current decolorization method for oil comprises the following steps:

7. An oil countercurrent decolorization system, comprising:

8. The oil countercurrent decolorization system according to claim 7, characterized in that: the device also comprises a premixing device, a fresh decoloring agent feeding port and a fresh decoloring agent discharging port, wherein the premixing device is provided with a premixed oil inlet and a premixed oil outlet; the premixed oil inlet is communicated with the first filtrate outlet of the first filtering device, and the premixed oil outlet is communicated with the second oil inlet.

9. The oil countercurrent decolorization system according to claim 7 or 8, characterized in that: and a slurry caching device is also arranged on a pipeline which is communicated with the filtered slurry outlet and the recycled decolorizer inlet of the pre-decolorization device.

10. The oil countercurrent decolorization system according to claim 9, characterized in that:

a first conveying pump is further arranged on a pipeline through which the first filtering device oil inlet is communicated with the first oil outlet; and/or

And a second delivery pump is also arranged on a pipeline for communicating the slurry caching device with a recycled decolorizer inlet of the pre-decolorization device.