A waste oil chemical pretreatment system

Abstract

The application discloses a kind of waste oil chemical pretreatment systems, including catalyst configuration device, first esterification reactor, first separation device, second separation device, evaporation device group, cooling device and methanol separation device, one of the outlet ends of first esterification reactor is communicated with first separation device, the outlet end of first separation device is communicated with the inlet end of second separation device, the first outlet end of second separation device is communicated with one of evaporation device, the second outlet end of second separation device is communicated with another evaporation device, the outlet end of multiple evaporation devices is simultaneously communicated with cooling device, cooling device is communicated with methanol separation device again, one of the outlet ends of methanol separation device is communicated with reflux device, reflux device is communicated with first esterification reactor.The system can effectively reduce the acid value of waste oil and remove the metal, phospholipid, unsaponifiable matter and other impurities in it, the overall efficiency is high in operating process, energy consumption is small, production benefit is better.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of renewable energy, in particular to a waste oil chemical pretreatment system. BACKGROUND

[0002] Developing biodiesel production projects not only meets the demand of the country to develop clean energy, but also meets the current national goal of "carbon peak and carbon neutral". According to industry test data, 2.0-2.5 tons of carbon emissions can be reduced per ton of biodiesel used in the whole cycle. According to the Dutch Double Counting certification of the largest global biomass energy consumption area, the European Union, compared with biodiesel produced from palm oil, soybean oil, rapeseed oil and other plant oils, biodiesel produced from waste oil, hogwash oil, acidified oil and other waste oils has higher carbon emission reduction properties and should be vigorously promoted. Waste oil is a widely available byproduct of edible oil processing, and compared with animal and plant oils and microbial oils, it is relatively inexpensive to use as a raw material for the production of second-generation biodiesel by hydrogenation and deoxidation.

[0003] However, waste oil has high fatty acid content and high acid value, and the hydrogenation and deoxidation reaction is carried out at high temperature and generates a large amount of water, which seriously affects the stability of the hydrogenation catalyst and causes the catalyst bed to be easily powdered and deactivated. In addition, waste oil also contains a large amount of metal, phospholipid, unsaponifiable matter and other impurities, which will also affect the stability of the hydrogenation catalyst on the surface of the hydrogenation catalyst. Therefore, when waste oil is used as a raw material to produce second-generation biodiesel, the device needs to be frequently shut down and the catalyst needs to be replaced, which cannot be operated stably for a long period of time, and the operating cost is high. In the current hydrogenation and deoxidation method for preparing second-generation biodiesel, conventional water method, acid washing, alkali washing, adsorption and other physical methods are usually used to pretreat waste oil. Although a part of the impurities can be removed, the overall efficiency is low, and the conventional physical pretreatment method cannot fundamentally solve the problem of high acid value of waste oil. SUMMARY

[0004] In view of the problem that the conventional water method, acid washing, alkali washing, adsorption and other physical methods used in the prior art have low impurity removal efficiency and cannot effectively reduce the acid value of waste oil, the present application provides a chemical pretreatment system that can effectively reduce the acid value of waste oil and remove impurities therein. The raw material oil loss rate is low and the operating cost is not high, the overall energy consumption is low during system operation, and the material recycling rate is high.

[0005] The present application adopts the following technical solutions:

[0006] A waste oil chemical pretreatment system, comprising a catalyst configuration device, a first esterification reactor, a first separation device, a second separation device, an evaporation device group, a cooling device, a methanol separation device, a reflux device and a raw oil supply device, the catalyst configuration device is communicated with one inlet end of the first esterification reactor for introducing catalyst for raw oil reaction into the first esterification reactor, the raw oil supply device is communicated with another inlet end of the first esterification reactor for providing waste oil raw oil to the first esterification reactor, one outlet end of the first esterification reactor is communicated with the first separation device for separating solids in the product discharged from the first esterification reactor; the outlet end of the first separation device is communicated with the inlet end of the second separation device, the second separation device is used for further separating oil and water two phases in the product discharged from the first separation device; the evaporation device group comprises a first evaporation device and a second evaporation device, the first outlet end of the second separation device is communicated with the first evaporation device, and the second outlet end of the second separation device is communicated with the second evaporation device, the evaporation device group is used for evaporating oil and water two phases separated by the second separation device; the outlet end of the evaporation device group is communicated with the cooling device at the same time, the outlet of the cooling device is further communicated with the methanol separation device, the outlet end of the methanol separation device is communicated with the reflux device, the methanol separation device is used for rectifying and separating methanol and water, and the reflux device is communicated with the first esterification reactor. The methanol separated by the methanol separation device is introduced into the first esterification reactor through the reflux device.

[0007] The inlet of the catalyst configuration device is communicated with an external methanol supply device and an ionic liquid catalyst supply device, the external methanol supply device provides methanol to the catalyst configuration device, and the ionic liquid catalyst supply device provides ionic liquid catalyst to the catalyst configuration device.

[0008] Preferably, a stirring device is arranged in the catalyst configuration device, and the stirring device is used for stirring ionic liquid and methanol liquid.

[0009] The outlet end of the catalyst configuration device is communicated with the inlet of a mixing device, the outlet of the mixing device is communicated with the inlet end of the first esterification reactor, and a transmission pump is arranged between the catalyst configuration device and the mixing device.

[0010] The catalyst configuration device is communicated with at least one evaporation device in the evaporation device group through a pipeline, and a valve is arranged on the pipeline between the catalyst configuration device and the communicated evaporation device.

[0011] The system further comprises a second esterification reactor, an outlet end of the first esterification reactor is communicated with an inlet end of the second esterification reactor, and an outlet end of the second esterification reactor is communicated with the first separation device, and the second esterification reactor is used for further reacting the unreacted raw oil and methanol after the reaction in the first esterification reactor.

[0012] The evaporation device group comprises a first evaporation device and a second evaporation device arranged in parallel, the first evaporation device is used for separating the oil phase product separated by the second separation device, and the second evaporation device is used for separating the water phase product separated by the second separation device.

[0013] The first evaporation device comprises a first evaporator and a first gas-liquid separator arranged in series, the first evaporator is used for heating and warming the oil phase product, and the warmed oil phase product is introduced into the first gas-liquid separator in communication for further gas-liquid separation.

[0014] The second evaporation device comprises a second evaporator and a second gas-liquid separator arranged in series, the second evaporator is used for heating and warming the water phase product, and the warmed water phase product is introduced into the second gas-liquid separator in communication for further gas-liquid separation.

[0015] The first gas-liquid separator and the second gas-liquid separator are arranged in parallel and are simultaneously communicated with the cooling device, and the methanol and water discharged from the first gas-liquid separator and the methanol and water discharged from the second gas-liquid separator are all introduced into the cooling device.

[0016] Preferably, the first esterification reactor and the second esterification reactor are both stirred tank reactors.

[0017] Preferably, the first separation device is a filter, and the second separation device is a chromatograph.

[0018] The technical scheme of the present application has the following advantages:

[0019] The waste oil chemical pretreatment system provided by the present application uses methanol and ionic liquid to prepare a catalyst solution, and then mixes the methanol after reaction circulation with raw oil to be treated, so that the methanol and the raw oil can be esterified under the action of the catalyst to generate fatty acid methyl ester and water, thereby achieving the purpose of reducing the acid value of the raw oil and removing impurities such as metals, phospholipids and unsaponifiable matter in the raw oil, and the loss rate of the raw oil is low, the operation process is not high in cost, and the overall energy consumption in the system operation process is low. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present application, the drawings required to be used in the specific embodiments will be briefly introduced as follows. Obviously, the drawings described in the following description are some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative labor based on the embodiments of the present application also belong to the protection scope of the present application.

[0021] Fig. 1 Figure 1 is a schematic diagram of the overall structure of the waste oil chemical pretreatment system of the present application (1);

[0022] Fig. 2 Figure 1 is a schematic diagram of the overall structure of the waste oil chemical pretreatment system of the present application (2).

[0023] The figures are identified as follows:

[0024] 1-catalyst configuration device; 2-esterification reactor, 21-first esterification reactor, 22-second esterification reactor; 3-first separation device; 4-second separation device, 41-first outlet end, 42-second outlet end; 5-evaporation device group, 51-first evaporation device, 511-first evaporator, 512-first gas-liquid separator, 52-second evaporation device, 521-second evaporator, 522-second gas-liquid separator; 6-cooling device; 7-methanol separation device; 8-reflux device; 9-methanol feed pump; 10-mixing device; 20-raw oil supply device. Specific embodiments

[0025] The technical solutions of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor also belong to the protection scope of the present application.

[0026] As Figs. 1-2As shown, the present application provides a waste oil chemical pretreatment system, which comprises a catalyst configuration device 1, a first esterification reactor 21, a first separation device 3, a second separation device 4, an evaporation device group 5, a cooling device 6, a methanol separation device 7, a reflux device 8 and a raw material oil supply device 20. The catalyst configuration device 1 is in communication with one inlet end of the first esterification reactor 21 for introducing catalysts for raw material oil reaction into the first esterification reactor 21. The raw material oil supply device 20 is in communication with another inlet end of the first esterification reactor 21 for providing waste oil as raw material oil into the first esterification reactor 21. One outlet end of the first esterification reactor 21 is in communication with the first separation device 3 for separating solids in the product discharged from the first esterification reactor 21. The outlet end of the first separation device 3 is in communication with the inlet end of the second separation device 4 for further separating oil-water two-phase in the product discharged from the first separation device 3. The evaporation device group 5 comprises a first evaporation device 51 and a second evaporation device 52. The first outlet end 41 of the second separation device 4 is in communication with the first evaporation device 51, and the second outlet end 42 of the second separation device 4 is in communication with the second evaporation device 52. The evaporation device group 5 is used for evaporating the oil-water two-phase separated by the second separation device 4 to obtain methanol and water. The outlet end of the evaporation device group 5 is in communication with the cooling device 6. The outlet of the cooling device 6 is in communication with the methanol separation device 7. The outlet end of the methanol separation device 7 is in communication with the reflux device 8. The cooling device 6 is used for cooling the methanol and water obtained by the evaporation device group 5. The methanol separation device 7 is used for rectifying and separating methanol and water. The reflux device 8 is in communication with the first esterification reactor 21. The methanol rectified and separated by the methanol separation device 7 is introduced into the first esterification reactor 21 through the reflux device 8.

[0027] Further, the inlet of the catalyst preparation device 1 is communicated with an external methanol supply device and an ionic liquid catalyst supply device. The external methanol supply device supplies methanol with a purity greater than 99% to the catalyst preparation device 1, and the ionic liquid catalyst supply device supplies ionic liquid catalyst with a purity greater than 99% to the catalyst preparation device 1. The external methanol supply device and the catalyst preparation device 1 are connected by a pipeline, and a valve is arranged on the pipeline between the external methanol supply device and the catalyst preparation device 1. The flow of methanol liquid introduced into the catalyst preparation device 1 by the external methanol supply device is adjusted by controlling the valve, so as to improve the flexibility of catalyst preparation to adapt to the requirements of waste oil pretreatment under different conditions. The ionic liquid catalyst supply device introduces ionic liquid catalyst into the catalyst preparation device 1, and the ionic liquid catalyst supply device is fixed directly above the catalyst preparation device 1, so as to supplement the ionic liquid catalyst into the catalyst preparation device 1 in time and ensure sufficient preparation of the catalyst solution. In order to better utilize the remaining ionic liquid catalyst in the system reaction process, thereby reducing the consumption of ionic liquid catalyst in the chemical pretreatment process of waste oil, the catalyst preparation device 1 is communicated with at least one evaporation device in the evaporation device group 5. The catalyst preparation device 1 and the connected evaporation device are connected by a pipeline, and a valve is arranged on the pipeline between the catalyst preparation device 1 and the connected evaporation device. The flow of ionic liquid catalyst introduced into the catalyst preparation device 1 from the corresponding evaporation device is adjusted by controlling the valve, so as to improve the production flexibility of the whole system. The remaining ionic liquid catalyst after evaporation and recycling is discharged from the evaporation device and introduced into the catalyst preparation device 1, so as to prepare the catalyst. The catalyst is prepared by using part of the recycled ionic liquid, thereby reducing the consumption of ionic liquid in the catalyst preparation process, reducing the preparation cost, and improving the material utilization rate of the system. The catalyst preparation device 1 is provided with a stirring device for stirring the ionic liquid and the methanol liquid, so as to promote the dissolution and mixing of methanol and ionic liquid. The ionic liquid catalyst is a Bronsted acid proton type ionic liquid.

[0028] The outlet end of the catalyst preparation device 1 is communicated with the mixing device 10 by a pipeline, and the mixing device 10 is communicated with the inlet of the first esterification reactor 21. Specifically, the outlet end of the catalyst preparation device 1 is provided with a transfer pump for introducing the prepared catalyst solution from the catalyst preparation device 1 into the mixing device 10 for sufficient mixing, so that the catalyst solution can quickly participate in the reaction of methanol and raw oil after entering the first esterification reactor 21, thereby improving the reaction efficiency of the esterification reaction and reducing the overall reaction time. In order to make the catalyst solution play a more effective catalytic role, the prepared catalyst solution is introduced into the first esterification reactor 21 after being placed in the mixing device 10 for 5-10 minutes.

[0029] The first esterification reactor 21 is also in communication with an external raw oil supply device. In order to further utilize the materials after reaction in the system, the first esterification reactor 21 can be directly in communication with the methanol separation device 7, and the methanol separated by the methanol separation device 7 is introduced into the first esterification reactor 21 to continue the esterification reaction with the raw oil to generate fatty acid methyl ester and water; the generated fatty acid methyl ester and water are discharged from the first esterification reactor 21 and introduced into the first separation device 3 for subsequent separation.

[0030] In order to better react the raw oil and improve the reaction efficiency of the entire system, the system further comprises a second esterification reactor 22, the outlet end of the first esterification reactor 21 is in communication with the inlet end of the second esterification reactor 22, and the second esterification reactor 22 is used to further react the unreacted raw oil and methanol after reaction in the first esterification reactor 21 to further promote the esterification reaction of the raw oil and methanol to generate fatty acid methyl ester and water. The first esterification reactor 21 and the second esterification reactor 22 are both stirred tank reactors, the first esterification reactor 21 and the second esterification reactor 22 both have coiled heating pipes inside, and the first esterification reactor 21 and the second esterification reactor 22 both have circulating heat exchangers outside, wherein the heating pipes inside the first esterification reactor 21 and the second esterification reactor 22 circulate steam condensate, the methanol of the raw oil is heated by the steam condensate to promote the esterification reaction of the methanol of the raw oil; the circulating heat exchangers are in communication with a cooling water pipeline, and the temperature of the outer wall of the first esterification reactor 21 and the second esterification reactor 22 is adjusted and controlled by introducing cold water in the cooling water pipeline. In order to more effectively control the pressure inside the first esterification reactor 21 and the second esterification reactor 22, the first esterification reactor 21 and the second esterification reactor 22 are respectively in communication with a nitrogen pipeline, and the pressure inside the first esterification reactor 21 and the second esterification reactor 22 is adjusted by introducing nitrogen into the first esterification reactor 21 and the second esterification reactor 22.

[0031] The products generated after reaction in the first esterification reactor 21 and the second esterification reactor 22 are respectively discharged from the outlet end of the first esterification reactor 21 and the outlet end of the second esterification reactor 22 and introduced into the first separation device 3 for preliminary separation. The first separation device 3 is a filter, which can preliminarily remove the solid impurities in the products after reaction in the first esterification reactor 21 and the second esterification reactor 22; the outlet end of the first separation device 3 is in communication with a waste residue treatment storage tank, and the filtered solid impurities are discharged from the first separation device 3 and introduced into the waste residue treatment storage tank for centralized collection; the first separation device is preferably a plate and frame filter press.

[0032] The product separated by the first separation device 3 enters the second separation device 4, which is a chromatograph. The two outlet ends of the second separation device 4 are respectively connected to two evaporation devices. The second separation device 4 is used to separate the product filtered by the first separation device 3 into oil and water phases, to obtain an oil phase product and a water phase product. The oil phase product mainly contains fatty acid methyl ester, methanol, water and part of the unreacted raw oil, and the water phase product mainly contains methanol, ionic liquid and water generated in the reaction. The evaporation device group 5 includes a first evaporation device 51 and a second evaporation device 52, which are connected in parallel. The first evaporation device 51 is used to separate the oil phase product separated by the second separation device 4. The first evaporation device 51 includes a first evaporator 511 and a first gas-liquid separator 512 connected in series. The first evaporator 511 is used to heat the oil phase product. The heated oil phase product is introduced into the first gas-liquid separator 512 for further gas-liquid separation. The first gas-liquid separator 512 is used to separate the heated oil phase product into gas and liquid. Specifically, the oil phase product is heated to separate methanol and water from the oil phase product by using the difference in boiling points of water, methanol and fatty acid methyl ester. The remaining crude product containing fatty acid methyl ester and unreacted raw oil is discharged from the first gas-liquid separator 512 and introduced into a storage device for subsequent reaction. The first evaporation device 51 is connected to a steam heating pipeline, which is also connected to the first esterification reactor 21. Steam with a high temperature is introduced into the steam heating pipeline to transfer heat to the oil phase product in the first evaporation device 51 to promote the heating of the oil phase product. The cooled steam is then introduced into the first esterification reactor 21 to control the reaction temperature in the first esterification reactor 21.

[0033] Similarly, the second evaporation device 52 is used for separating the water phase product separated by the second separation device 4, and the second evaporation device 52 comprises a second evaporator 521 and a second gas-liquid separator 522 which are in communication with each other. The second evaporator 521 is used for heating the water phase product, and the heated water phase product enters the second gas-liquid separator 522 in communication for further gas-liquid separation. The second gas-liquid separator 522 is used for separating the heated water phase product into gas and liquid. Specifically, the ion liquid, methanol and water are separated by flash evaporation by using the boiling point difference between the ion liquid and methanol and water, and methanol and water are obtained by evaporation, so as to separate the methanol, water and ion liquid; the separated methanol and water are discharged from the second evaporation device 52 for further separation. In order to reuse the separated ion liquid catalyst, reduce the consumption of catalyst of the waste oil chemical pretreatment system, and reduce the pretreatment cost, the second gas-liquid separator 522 is in communication with the catalyst preparation device 1. After the separated ion liquid catalyst is discharged from the second gas-liquid separator 522, it can be introduced into the catalyst preparation device 1 for preparation of the catalyst solution, thereby reducing the cost of the system. Among the separated ion liquid catalyst, there are some deactivated ion liquids. In order to reduce the influence of the deactivated ion liquid catalyst on the subsequent reaction, the second gas-liquid separator 522 is further provided with a separation device for separating the deactivated ion liquid catalyst and the recyclable ion liquid, and discharging the deactivated ion liquid from the second gas-liquid separator 522 for recycling and collection.

[0034] The second evaporation device 52 is in communication with a steam heating pipeline, and the steam heating pipeline is also in communication with the first esterification reactor 21. By introducing steam with a higher temperature into the steam heating pipeline, heat is transferred to the water phase product in the second evaporation device 52 along with the flow of the steam, so as to promote the heating of the water phase product. By using steam to heat the water phase product, the cooled steam after heating is then introduced into the first esterification reactor 21 for controlling the reaction pressure in the first esterification reactor 21.

[0035] The first gas-liquid separator 512 and the second gas-liquid separator 522 are arranged in parallel with each other, and the first gas-liquid separator 512 and the second gas-liquid separator 522 are in communication with the cooling device 6 at the same time. The methanol and water discharged from the first gas-liquid separator 512 and the methanol and water discharged from the second gas-liquid separator 522 all enter the cooling device 6, and the cooling device 6 can further cool the methanol and water introduced from the first gas-liquid separator 512 and the second gas-liquid separator 522. The cooling device is a methanol condenser.

[0036] The outlet end of the cooling device 6 is communicated with the inlet end of the methanol separation device 7, and the methanol and water cooled by the cooling device 6 enter the methanol separation device 7. The cooling device 6 and the methanol separation device 7 are communicated by a pipeline, and a methanol feeding pump 9 is arranged on the pipeline connecting the cooling device 6 and the methanol separation device 7. The methanol feeding pump 9 can increase the pressure in the pipeline, so that the methanol and water can enter the methanol separation device 7 faster. The methanol separation device 7 can distill and separate the cooled methanol and water, and obtain methanol with a purity of more than 99%. In order to better promote the reaction of the raw oil and improve the recycling rate of the system, the outlet of the methanol separation device 7 is communicated with the reflux device 8, and the separated methanol with a purity of more than 99% is introduced into the reflux device 8. The reflux device 8 is communicated with the first esterification reactor 21, and the reflux device 8 can re-introduce the methanol with a purity of more than 99% into the first esterification reactor 21 for continuous reaction with the raw oil to generate fatty acid methyl ester and water, thereby achieving the effect of recycling of methanol. The waste water after distillation is discharged from the bottom of the methanol separation device 7 and introduced into the waste water storage device.

[0037] In specific use, methanol and ionic liquid catalyst are introduced into the catalyst configuration device 1 at the same time. In order to reduce the consumption of raw materials by the system, the ionic liquid catalyst separated in the second gas-liquid separator 522 is introduced into the catalyst configuration device 1 at the same time. The methanol and ionic liquid catalyst are mixed and stirred uniformly by the catalyst configuration device 1 to form a catalyst solution. The catalyst solution is discharged from the catalyst configuration device 1, introduced into the mixing device 10 and left in the mixing device 10 for 6-8 minutes, and then introduced into the first esterification reactor 21. At this time, the raw oil and methanol are introduced into the first esterification reactor 21 at the same time for esterification reaction. In order to effectively utilize the materials in the system and reduce the consumption of external raw materials, thereby reducing the operating cost, the methanol separated by the methanol separation device 7 is introduced into the first esterification reactor 21. At the same time, the reaction temperature and reaction pressure in the first esterification reactor 21 are adjusted. Under the action of the ionic liquid catalyst, the methanol and the raw oil undergo esterification reaction to generate fatty acid methyl ester and water. The unreacted methanol and raw oil are introduced into the second esterification reactor 22 through the first esterification reactor 21, and the reaction temperature and reaction pressure of the second esterification reactor 22 are adjusted to make the methanol and the raw oil further undergo esterification reaction.

[0038] The fatty acid methyl ester and water generated after the reaction of the first esterification reactor 21 and the second esterification reactor 22 are discharged from the first esterification reactor 21 and the second esterification reactor 22 respectively and then enter the first separation device 3 for filtration to preliminarily remove the solid impurities in the product; after the filtration, the product is discharged from the first separation device 3 and introduced into the second separation device 4, and the product is separated into an oil phase product and a water phase product by the second separation device 4, the oil phase product enters the first evaporation device 51 connected with the second separation device 4, and the water phase product enters the second evaporation device 52 connected with the second separation device 4, the first evaporation device 51 further separates the oil phase product by evaporation to obtain methanol and water by using the boiling point difference of water, methanol and fatty acid methyl ester; the second evaporation device 52 further separates the water phase product by evaporation to obtain methanol and water by using the boiling point difference of ionic liquid, methanol and water. The methanol and water evaporated from the first evaporation device 51 and the second evaporation device 52 are simultaneously introduced into the cooling device 6 for condensation to obtain methanol and water liquid, the condensed methanol and water liquid are discharged from the cooling device 6 and then introduced into the methanol separation device 7, the methanol separation device 7 further rectifies the introduced methanol and water liquid to obtain methanol with a purity greater than 99%, and the waste water after the rectification is discharged from the methanol separation device 7.

[0039] The unmentioned part of the present application is applicable to the prior art.

[0040] Obviously, the above embodiments are only examples for clearly illustrating the present application and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A waste oil and fat chemical pretreatment system, characterized by, The device comprises a catalyst arrangement device (1), a first esterification reactor (21), a first separation device (3), a second separation device (4), an evaporation device group (5), a cooling device (6), a methanol separation device (7), a reflux device (8) and a raw oil supply device (20), the catalyst arrangement device (1) is communicated with one inlet end of the first esterification reactor (21) for introducing catalysts for raw oil reaction into the first esterification reactor (21), the raw oil supply device (20) is communicated with another inlet end of the first esterification reactor (21) for providing waste oil and fat as raw oil into the first esterification reactor (21), one outlet end of the first esterification reactor (21) is communicated with the first separation device (3) for separating solid in the product discharged from the first esterification reactor (21); the outlet end of the first separation device (3) is communicated with the inlet end of the second separation device (4), the second separation device (4) is used for further separating oil-water two-phase in the product discharged from the first separation device (3); the evaporation device group (5) comprises a first evaporation device (51) and a second evaporation device (52), the first outlet end (41) of the second separation device (4) is communicated with the first evaporation device (51), the second outlet end (42) of the second separation device (4) is communicated with the second evaporation device (52), the evaporation device group (5) is used for evaporating oil-water two-phase separated by the second separation device (4); the outlet end of the evaporation device group (5) is communicated with the cooling device (6) at the same time, the outlet of the cooling device (6) is communicated with the methanol separation device (7), the outlet end of the methanol separation device (7) is communicated with the reflux device (8), the methanol separation device (7) is used for rectifying and separating methanol and water, the reflux device (8) is communicated with the first esterification reactor (21), the methanol rectified and separated by the methanol separation device (7) is introduced into the first esterification reactor (21) through the reflux device (8); The inlet of the catalyst arrangement device (1) is communicated with an external methanol supply device and an ionic liquid catalyst supply device, the external methanol supply device provides methanol for the catalyst arrangement device (1), and the ionic liquid catalyst supply device provides ionic liquid catalysts for the catalyst arrangement device (1); The evaporation device group (5) comprises the first evaporation device (51) and the second evaporation device (52) arranged in parallel, the first evaporation device (51) is used for separating oil phase products separated by the second separation device (4), and the second evaporation device (52) is used for separating water phase products separated by the second separation device (4). The first evaporation device (51) comprises a first evaporator (511) and a first gas-liquid separator (512) arranged in series, the first evaporator (511) is used for heating and warming the oil phase product, and the warmed oil phase product is introduced into the first gas-liquid separator (512) in communication for further gas-liquid separation; The second evaporation device (52) comprises a second evaporator (521) and a second gas-liquid separator (522) arranged in series, the second evaporator (521) is used for heating and warming the water phase product, and the warmed water phase product is introduced into the second gas-liquid separator (522) in communication for further gas-liquid separation.

2. The waste oil chemical pretreatment system according to claim 1, characterized in that: The outlet end of the catalyst configuration device (1) is in communication with the inlet of the mixing device (10), the outlet of the mixing device (10) is in communication with the inlet end of the first esterification reactor (21), and a transmission pump is arranged between the mixing device (10) and the catalyst configuration device (1).

3. The waste oil chemical pretreatment system of claim 2, wherein: The catalyst configuration device (1) is in communication with at least one evaporation device in the evaporation device group (5) through a pipeline, and a valve is arranged on the pipeline between the catalyst configuration device (1) and the connected evaporation device.

4. The waste oil chemical pretreatment system of claim 3, wherein: The system further comprises a second esterification reactor (22), another outlet end of the first esterification reactor (21) is in communication with the inlet end of the second esterification reactor (22), the outlet end of the second esterification reactor (22) is in communication with the first separation device (3), and the second esterification reactor (22) is used for further reaction of the unreacted raw oil and methanol after the reaction in the first esterification reactor (21).

5. The waste oil chemical pretreatment system of claim 4, wherein: The first gas-liquid separator (512) and the second gas-liquid separator (522) are arranged in parallel, the first gas-liquid separator (512) and the second gas-liquid separator (522) are in communication with the cooling device (6) at the same time, the methanol and water discharged from the first gas-liquid separator (512) and the methanol and water discharged from the second gas-liquid separator (522) all enter the cooling device (6).

6. The waste oil chemical pretreatment system according to claim 5, wherein: The first esterification reactor (21) and the second esterification reactor (22) are both stirred tank reactors; The first separation device (3) is a filter, and the second separation device (4) is a chromatograph. The first esterification reactor (21) and the second esterification reactor (22) are both stirred tank reactors; The first separation device (3) is a filter, and the second separation device (4) is a chromatograph.

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