A cracking oil separation and purification device and method

Abstract

The invention relates to the field of oil separation and purification, and specifically provides a cracking oil separation and purification device and method, comprising a raw oil temporary storage tank, an alkali washing tank, a liquid separation tank and an oil temporary storage tank which are connected in sequence; wherein the alkali washing tank and the liquid separation tank are arranged as two groups connected in parallel, and a tank dumping pump is arranged between each group of the alkali washing tank and the liquid separation tank; in addition, an alkali solution regulating tank and a fresh alkali solution storage tank are also arranged; by using the above device, the cracking oil liquid can be sent to the raw oil temporary storage tank for static sedimentation, the separated oil liquid can be sent to the alkali washing tank for spraying alkali washing with alkali solution to remove inorganic chlorine components in the oil liquid, and finally the qualified oil product on the upper layer of the liquid separation tank can be sent to the oil temporary storage tank to complete the treatment of the oil product, and finally a higher quality cracking oil product can be obtained.

Description

Technical Field

[0001] The invention relates to the field of oil separation and purification, and specifically provides a cracking oil separation and purification device and method. Background Art

[0002] Waste rubber and waste plastic are both difficult-to-process waste flexible polymer materials, which are composed of polymer polymerization. These materials have a large molecular weight and are difficult to effectively treat by conventional treatment methods. They are generally treated by incineration combined with deep burial, but this treatment method will have a more serious impact on the environment. Therefore, how to treat these materials is an urgent problem to be solved. In the prior art, treating these materials by high-temperature cracking is a good choice. The inventor of this application has provided several feasible cracking technology solutions, which can produce a large amount of recoverable oil and gas after the polymer material is cracked. The effective recovery and utilization of these oil and gas resources can obtain objective economic and social benefits.

[0003] However, during the production process, the inventors discovered that the composition of this part of oil and gas is relatively complex, and the components of oil and gas from different sources are different. In addition, during the cracking process, the chlorine-containing components in the raw materials will be converted into inorganic chlorine, such as hydrogen chloride, which remains in the oil and gas. After the oil and gas are condensed, the hydrogen chloride part is wrapped in the oil droplets and then converted into the oil. At the same time, fillers such as carbon black in waste rubber and waste plastics will also be mixed in the oil in particles after cracking, which ultimately leads to the oil containing impurity components such as inorganic chlorine, solid slag and water. Such oil cannot be directly used in post-processing.

[0004] The inventor's prior application CN202111174073.9 discloses a multi-stage cooling and purification device for cracked oil and gas, which can improve the purity of cracked gas through multi-stage cooling. However, the device is suitable for gaseous components and cannot separate and purify the condensed oil. Therefore, how to separate and purify the oil products containing impurity components such as inorganic chlorine, solid slag and moisture to improve the quality of cracked oil products has become one of the technical problems that the inventor has worked hard to solve. Summary of the invention

[0005] In view of the above problems, the present invention proposes a cracking oil separation and purification device and method, the device comprises a raw oil temporary storage tank, an alkali washing tank, a liquid separator and an oil temporary storage tank connected in sequence; wherein the alkali washing tank and the liquid separator are arranged as two groups in parallel, and a tank dumping pump is arranged between each group of the alkali washing tank and the liquid separator; in addition, an alkali solution regulating tank and a fresh alkali solution storage tank are arranged; by means of the above device, the cracking oil can be sent to the raw oil temporary storage tank for static sedimentation, the separated oil can be sent to the alkali washing tank for spraying alkali washing with alkali solution to remove inorganic chlorine components in the oil, and part of the alkali washing oil can be sent to the liquid separator for static stratification during the alkali washing to improve the efficiency of the alkali washing, and finally the qualified oil on the upper layer of the liquid separator tank can be sent to the oil temporary storage tank to complete the treatment of the oil. By using the above-mentioned device and the corresponding treatment method, the water and solid residue contained in the oil can be removed first, and then the inorganic chlorine component can be removed by alkaline washing. The two sets of alkaline washing tanks and liquid separation tanks arranged in parallel can realize continuous treatment, and finally higher quality cracking oil products can be obtained.

[0006] The pyrolysis oil products targeted by the present invention are mainly derived from waste plastics and waste rubber. After the pyrolysis oil gas is condensed, the main impurities in the oil products are water, inorganic chlorine and solid residue. The content of these components is generally ≤10wt% water, ≤1wt% solid residue, and the content of inorganic chlorine is 500-3000ppm depending on the raw materials. These impurities directly enter the subsequent distillation process with the oil products, which will cause a serious decline in the quality of the oil products and damage the distillation device. Therefore, it is necessary to separate and remove them as much as possible to obtain high-quality oil products. For this purpose, the main processing steps adopted by the inventor are as follows:

[0007] A method for separating and purifying cracked oil products comprises the following steps: firstly, condensed cracked oil is sent into a crude oil temporary storage tank for static sedimentation, so that oil, water and solid residue are separated into layers under the action of gravity; the upper layer of oil products in the crude oil temporary storage tank is sent into an alkali washing tank, inorganic chlorine in the oil products is neutralized by spraying alkali solution, part of the mixed solution of alkali solution and oil products is transferred to a liquid separation tank through a first pipeline for separation, the oil liquid is collected in the upper layer, the alkali solution settles to the lower layer, the upper layer of oil liquid is sent into an oil product temporary storage tank for storage, and the lower layer of alkali solution is sent back to the top of the alkali washing tank through a second pipeline to continue to react with the oil products or sent into an alkali solution regulating tank for storage; the water and solid residue separated in the crude oil temporary storage tank are respectively discharged from the crude oil temporary storage tank and processed separately.

[0008] Further processing steps are as follows:

[0009] First, the oil, water and solid residue are separated under the action of gravity by the method of static sedimentation, so a crude oil temporary storage tank is set, and a heat preservation heating layer is set on the tank to maintain the temperature inside the tank, so as to ensure that the oil product will not solidify due to cooling. The heating method adopted can be electric heating or heat exchange by hot water. The condensed cracking oil is sent into the middle of the crude oil temporary storage tank as the crude oil, and the lower part of the crude oil temporary storage tank is provided with a liquid outlet, and the bottom is provided with a solid residue outlet. The cracking oil is separated after sedimentation in the tank, and the solid residue is precipitated at the bottom of the tank. The middle layer is a mixture of water and a small amount of oil products, and the upper layer is oil products. In this way, the separation of solid and liquid, and the separation of a large amount of water and oil products are achieved. The solid oil residue can be discharged for treatment by regular discharge through the solid residue outlet; the mixture of water and a small amount of oil products in the middle layer is discharged through the liquid outlet, and is detected after entering the observation water tank. If the oil content is too high, it re-enters the crude oil temporary storage tank with the newly entered cracking oil to enter and exit the sedimentation. If the oil content is low, it can be directly sent to the water treatment process for treatment.

[0010] The upper layer of the crude oil temporary storage tank still contains inorganic chlorine and a small amount of water. At this time, it is sent to the alkali washing tank. A spraying device is provided in the alkali washing tank. The spraying device is connected to the fresh alkali solution storage tank through a pipeline. The inorganic chlorine in the oil is neutralized by spraying alkali solution, so that it is transferred from the oil to the alkali solution, thereby reducing the inorganic chlorine content in the oil. Preferably, a circulating pump is provided outside the alkali washing tank to realize the circulating spraying of alkali solution, thereby increasing the reaction time of alkali solution and oil. A thermal insulation heating layer is also provided in the alkali washing tank to maintain the temperature inside the tank, ensuring that the oil will not solidify due to cooling and promoting the rapid progress of the neutralization reaction. The heating method adopted can be electric heating or heat exchange through hot water.

[0011] The alkali solution in the alkali washing tank is selected from a NaOH solution or a KOH solution with a mass concentration of 20-30%, and the flow ratio of the oil product to the alkali solution in the alkali washing tank is 2-4:1.

[0012] The alkali washing tank is connected to the liquid separation tank through a pipeline and a tank inversion pump, wherein the pipeline is divided into two routes, wherein the first pipeline is connected from the bottom of the alkali washing tank to the tank inversion pump, and then connected to the top of the liquid separation tank; the other second pipeline is connected from the bottom of the liquid separation tank to the tank inversion pump, and then connected to the spray device on the top of the alkali washing tank; and the tank inversion pump is also connected to the alkali solution regulating tank through a pipeline. The specific working process of the above-mentioned tank dumping pump is as follows: when the volume of the alkali liquid and the oil product in the alkali washing tank reaches 50-70% of the liquid level in the tank, the connection between the raw oil temporary storage tank and the alkali washing tank is disconnected, the tank dumping pump and the first pipeline are turned on, and part of the mixture of the alkali liquid and the oil product is transferred to the separator tank through the first pipeline, and the alkali liquid continues to react with the inorganic chlorine component in the oil product in the separator tank; at this time, the remaining mixture of the alkali liquid and the oil product in the alkali washing tank continues to circulate in the alkali washing tank through the circulation pump. Since part of the mixture has entered the separator tank, the remaining mixture can be circulated more times, thereby improving the efficiency of the reaction; and the oil after the reaction in the separator tank will be separated from the alkali liquid after standing, and the oil will gather in the upper layer, while the alkali liquid will gradually settle to the lower layer. When the reaction in the alkali washing tank reaches a certain time, the tank inversion pump and the second pipeline can be opened. At this time, the alkali solution in the lower layer of the liquid separation tank is sent back to the top of the alkali washing tank and enters the spray device to continue to contact and react with the oil. At this time, due to the obvious excess of alkali solution, the inorganic chlorine in the oil can be removed as much as possible; when the total time of all oil products staying in the alkali washing tank reaches 20-30 minutes. Open the tank inversion pump and the first pipeline, and send all the mixed liquids in the alkali washing tank into the liquid separation tank. At this time, the mixed liquid enters the liquid separation tank from the top of the liquid separation tank, and the oil in the upper layer of the liquid separation tank is mixed for the second time, and another mixing reaction is carried out. The oil in the upper layer of the liquid separation tank can be purified again, and then the mixed liquid is allowed to settle and stratify in the liquid separation tank, and the purified oil in the upper layer can be sent to the oil temporary storage tank; and the alkali solution at the bottom of the liquid separation tank can be sent to the alkali solution regulating tank for storage through the tank inversion pump and the corresponding pipeline.

[0013] After the above treatment, the water content of the oil product is reduced to below 0.5wt%, the inorganic chlorine removal rate reaches more than 95%, and it does not contain solid impurities, which is more convenient for subsequent treatments such as distillation.

[0014] The treatment process of the above-mentioned alkali washing tank and the liquid separator tank is an intermittent operation rather than a continuous operation. Therefore, the inventor chooses to set the alkali washing tank and the liquid separator tank as two groups in parallel, so that the two groups can work alternately to achieve continuous treatment of the pyrolysis oil. When the output of the pyrolysis oil is small, only one group of alkali washing tanks and liquid separator tanks can be used, and the other group can be kept on standby for maintenance. At this time, it is only necessary to extend the residence time of the pyrolysis oil in the crude oil temporary storage tank to meet the time interval of the alkali washing tank and the liquid separator tank.

[0015] Preferably, the bottom of the separator tank is also connected to the alkali liquid regulating tank through a pipeline, so that the reacted alkali liquid stored in the alkali liquid regulating tank can be sent back to the separator tank after sedimentation. When the oil in the separator tank is less and difficult to discharge from the top, this operation can increase the liquid level in the separator tank, so that the oil can be discharged more conveniently. At the same time, through the detection of the alkali liquid in the alkali liquid regulating tank, qualified alkali liquid can be sent back to the separator tank to participate in alkali washing again, thereby reducing the demand for fresh alkali liquid and reducing the processing cost.

[0016] Preferably, a heat-insulating heating layer is also provided in the liquid separation tank and the oil temporary storage tank to maintain the internal temperature of the tank.

[0017] In addition, the present application also provides a corresponding cracking oil separation and purification device, including a raw oil temporary storage tank, an alkali washing tank, a liquid separation tank and an oil temporary storage tank connected in sequence; wherein the alkali washing tank and the liquid separation tank are arranged as two groups in parallel, and a tank dumping pump is arranged between each group of alkali washing tanks and liquid separation tanks; in addition, an alkali solution regulating tank and a fresh alkali solution storage tank are also arranged.

[0018] Furthermore, the crude oil temporary storage tank, alkali washing tank, separation tank and oil product temporary storage tank are all provided with a heat preservation and heating layer, and a hot water jacket can be used for heat preservation and heating, and all hot water is delivered through a hot water pipeline.

[0019] The crude oil temporary storage tank is provided with a cracking oil inlet in the middle, a liquid outlet in the lower part, and a solid slag outlet at the bottom; the liquid outlet is connected to an observation water tank through a pipeline, and the observation water tank is connected to an external water pump.

[0020] The configuration of each group of alkali washing tanks and liquid separation tanks is the same, and the alkali washing tanks and the liquid separation tanks are connected through pipelines and tank inversion pumps, wherein the pipelines are divided into two routes, wherein the first pipeline is connected from the bottom of the alkali washing tank to the tank inversion pump, and then connected to the top of the liquid separation tank; the other second pipeline is connected from the bottom of the liquid separation tank to the tank inversion pump, and then connected to the spray device on the top of the alkali washing tank; and the tank inversion pump is also connected to the alkali solution regulating tank through a pipeline.

[0021] A circulation pump is arranged outside the alkali washing tank, one end of the circulation pump is connected to the bottom of the alkali washing tank through a pipeline, and the other end is connected to the spraying device on the top of the alkali washing tank to realize the circulation spraying of the alkali solution.

[0022] The alkali solution regulating tank is connected to a regulating pump, which is connected to the bottom of the liquid separation tank through the regulating pump, so that qualified alkali solution can be sent back to the liquid separation tank; an alkali solution delivery pump is arranged on the outside of the fresh alkali solution storage tank to deliver the fresh alkali solution to the spraying device of the alkali washing tank. The preferred alkali solution regulating tank is connected to the above-mentioned alkali solution delivery pump through a pipeline, and the alkali solution in the alkali solution regulating tank can be mixed with the fresh alkali solution according to the reaction situation and sent to the spraying device, thereby realizing the recycling of the alkali solution, reducing the amount of fresh alkali solution, and reducing the cost of the reaction. At the same time, the oil remaining in the alkali solution after the reaction can be sent back to the treatment system again, thereby improving the yield of the oil product and minimizing the oil content in the alkali solution after the reaction, which is also convenient for the treatment of the alkali solution after it is discarded.

[0023] In summary, by using the above-mentioned device and the corresponding treatment method provided by the present invention, the water and solid residue contained in the oil can be removed first, and then the inorganic chlorine component can be removed by alkali washing. The two sets of alkali washing tanks and liquid separation tanks arranged in parallel can realize continuous treatment, and finally a higher quality cracking oil product can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a schematic diagram of the process flow of the method for separating and purifying cracked oil products according to the present invention;

[0025] Figure 2 This is a schematic diagram of the connection structure of the cracking oil separation and purification device of the present invention;

[0026] In the figure, 1 is a temporary storage tank for raw oil, 2-1 is an alkali washing tank A, 3-1 is a liquid separation tank A, 2-2 is an alkali washing tank B, 3-2 is a liquid separation tank B, 4 is a temporary storage tank for oil products, 5 is an alkali solution regulating tank, 6 is a fresh alkali solution storage tank, 7-1 is a circulation pump A, 7-2 is a circulation pump B, 8-1 is a tank dumping pump A, 8-2 is a tank dumping pump B, 9 is a regulating pump, 10 is an alkali solution delivery pump, 11 is an observation water tank, 12 is an external water pump, and 13 is an external oil pump. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1 A device for improving the quality of cracked oil.

[0029] like Figure 2As shown, the inventor first provides a cracking oil separation and purification device, including a raw oil temporary storage tank 1, an alkali washing tank, a liquid separation tank and an oil temporary storage tank 4 connected in sequence; wherein the alkali washing tank and the liquid separation tank are arranged in two parallel groups, namely, an alkali washing tank A 2-1 and a liquid separation tank A 3-1; an alkali washing tank B 2-2 and a liquid separation tank B 3-2, and a tank dumping pump is arranged between each group of alkali washing tanks and liquid separation tanks, namely, a tank dumping pump A 8-1 and a tank dumping pump B 8-2; in addition, an alkali solution regulating tank 5 and a fresh alkali solution storage tank 6 are also arranged.

[0030] The crude oil temporary storage tank 1, alkali washing tank, separation tank and oil product temporary storage tank 4 are all provided with a heat preservation and heating layer, and a hot water jacket can be used for heat preservation and heating, and all hot water is delivered through a hot water circulation pipeline.

[0031] The crude oil temporary storage tank 1 is provided with a cracking oil inlet in the middle, a liquid outlet in the lower part, and a solid slag outlet at the bottom; the liquid outlet is connected to an observation water tank 11 through a pipeline, and the observation water tank 11 is connected to an external water pump 12.

[0032] The configuration of each group of alkali washing tanks and liquid separation tanks is the same, and the alkali washing tanks are connected to the liquid separation tanks through pipelines and tank inversion pumps, wherein the pipelines are divided into two routes, wherein the first pipeline is connected from the bottom of the alkali washing tank to the tank inversion pump, and then to the top of the liquid separation tank; the other second pipeline is connected from the bottom of the liquid separation tank to the tank inversion pump, and then to the spray device on the top of the alkali washing tank; and the tank inversion pump is also connected to the alkali solution regulating tank 5 through a pipeline.

[0033] A circulation pump is arranged outside each group of alkali washing tanks, namely, circulation pump A 7-1 and circulation pump B 7-2. One end of the circulation pump is connected to the bottom of the alkali washing tank through a pipeline, and the other end is connected to the spraying device on the top of the alkali washing tank to realize the circulation spraying of the alkali solution.

[0034] The alkali solution regulating tank 5 is connected to a regulating pump 9, which is connected to the bottom of the separator tank through the regulating pump 9, so that qualified alkali solution can be sent back to the separator tank; an alkali solution delivery pump 10 is arranged on the outside of the fresh alkali solution storage tank 6 to deliver fresh alkali solution to the spraying device of the alkali washing tank. The preferred alkali solution regulating tank 5 is connected to the above-mentioned alkali solution delivery pump 10 through a pipeline, and the alkali solution in the alkali solution regulating tank 5 can be mixed with the fresh alkali solution according to the reaction situation and sent to the spraying device, thereby realizing the recycling of alkali solution, reducing the amount of fresh alkali solution, and reducing the cost of the reaction. At the same time, the oil remaining in the alkali solution after the reaction can be sent back to the treatment system again, thereby improving the yield of oil products and minimizing the oil content in the alkali solution after the reaction, which is also convenient for the treatment of the alkali solution after disposal.

[0035] The oil temporary storage tank 4 is connected to an external oil pump 13 for sending the treated oil to the next processing step.

[0036] Example 2 A method for separating and purifying cracked oil products.

[0037] First, the condensed cracking oil is sent to the crude oil temporary storage tank 1 for static sedimentation, so that the oil, water and solid residue are separated into layers under the action of gravity; the upper layer of the crude oil temporary storage tank 1 is sent to the alkali washing tank, and the inorganic chlorine in the oil is neutralized by spraying alkali solution, and part of the mixed solution of the alkali solution and the oil is transferred to the liquid separation tank through the first pipeline for separation, and the oil is collected in the upper layer, and the alkali solution is settled to the lower layer. The upper layer of the oil is sent to the oil product temporary storage tank 4 for storage, and the lower layer of the alkali solution is sent back to the top of the alkali washing tank through the second pipeline to continue to react with the oil product or sent to the alkali solution regulating tank 5 for storage; the water and solid residue separated in the crude oil temporary storage tank 1 are discharged from the crude oil temporary storage tank 1 and then processed separately.

[0038] Example 3 A method for separating and purifying cracked oil products, such as Figure 1 As shown, the specific processing steps are as follows.

[0039] First, oil, water and solid slag are layered under gravity by the method of static sedimentation, so a crude oil temporary storage tank 1 is provided, and a heat-insulating heating layer is provided on the tank to maintain the internal temperature of the tank body, ensuring that the oil product will not solidify due to cooling, and the heating method adopted can be electric heating, or heat exchange can be performed by hot water. The pyrolysis oil to be processed is different according to the source, and its oil-water and solid slag content are different, but its component content is generally at moisture≤10wt%, solid slag≤1wt%, and inorganic chlorine content is distributed in 500-3000ppm according to different raw materials, so as long as the pyrolysis oil meeting the above-mentioned component content can adopt this method to process.

[0040] The pyrolysis oil after the condensation is sent into from the middle part of the stock oil temporary storage tank 1 as stock oil, the stock oil temporary storage tank 1 bottom is provided with a liquid outlet, and the bottom is provided with a solid residue outlet, the pyrolysis oil is layered after sedimentation in this tank, the solid residue is deposited at the tank bottom, the middle layer is a mixture of water and a small amount of oil products, and the upper layer is the oil product, so just realized the separation of solid and liquid, and the separation of a large amount of water and the oil product, the solid oil residue can be discharged for processing by the solid residue outlet regular discharging; the mixture of water and a small amount of oil products in the middle layer is discharged through the liquid outlet, enters the observation tank 11 and detects, if wherein the oil content is too high then re-enters the stock oil temporary storage tank 1 with the newly advanced pyrolysis oil and enters and exits the sedimentation, if the oil content is lower then can directly be sent to the water treatment process for processing.

[0041] The upper layer of the crude oil temporary storage tank 1 still contains inorganic chlorine and a small amount of water, and is now sent to an alkali washing tank. A spraying device is provided in the alkali washing tank, and the spraying device is connected to a fresh alkali solution storage tank 6 through a pipeline. The inorganic chlorine in the oil is neutralized by spraying alkali solution, so that it is transferred from the oil to the alkali solution, thereby reducing the inorganic chlorine content in the oil. Preferably, a circulating pump is provided outside the alkali washing tank to realize the circulating spraying of alkali solution, thereby increasing the reaction time of alkali solution and oil. An insulating heating layer is also provided in the alkali washing tank to maintain the temperature inside the tank, ensuring that the oil will not solidify due to cooling and promoting the rapid progress of the neutralization reaction. The heating method adopted can be electric heating or heat exchange through hot water.

[0042] The alkali solution in the alkali washing tank is selected from a NaOH solution or a KOH solution with a mass concentration of 20-30%, and the flow ratio of the oil product to the alkali solution in the alkali washing tank is 2-4: 1. In this embodiment, a NaOH solution with a mass concentration of 30% is preferably used, and the flow ratio of the oil product to the alkali solution in the alkali washing tank is 3: 1.

[0043] The alkali washing tank is connected to the liquid separation tank through a pipeline and a tank dump pump, wherein the pipeline is divided into two parts such as Figure 2As shown, the first pipeline ① is connected from the bottom of the alkali washing tank to the tank-turning pump, and then connected to the top of the liquid separation tank; the other second pipeline ② is connected from the bottom of the liquid separation tank to the tank-turning pump, and then connected to the spray device on the top of the alkali washing tank; and the tank-turning pump is also connected to the alkali solution regulating tank 5 through a pipeline. The specific working process of the above-mentioned tank dumping pump is as follows: when the volume of the alkali liquid and the oil product in the alkali washing tank reaches 50-70% of the liquid level in the tank, the connection between the raw oil temporary storage tank 1 and the alkali washing tank is disconnected, the tank dumping pump and the first pipeline are turned on, and part of the mixture of the alkali liquid and the oil product is transferred to the separator tank through the first pipeline, and the alkali liquid continues to react with the inorganic chlorine component in the oil product in the separator tank; at this time, the remaining mixture of the alkali liquid and the oil product in the alkali washing tank continues to circulate in the alkali washing tank through the circulation pump. Since part of the mixture has entered the separator tank, the remaining mixture can be circulated more times, thereby improving the efficiency of the reaction; and the oil after the reaction in the separator tank will be separated from the alkali liquid after standing, and the oil will be collected in the upper layer, while the alkali liquid will gradually settle to the lower layer. When the reaction in the alkali washing tank reaches a certain time, the tank pouring pump and the second pipeline can be opened continuously. At this time, the alkali solution in the lower layer of the separator tank is sent back to the top of the alkali washing tank and enters the spray device to continue to contact and react with the oil product. At this time, due to the obvious excess amount of alkali solution, the inorganic chlorine in the oil product can be removed as much as possible; when the total time that all the oil products stay in the alkali washing tank reaches 30 minutes, the tank pouring pump and the first pipeline are opened to send all the mixed liquids in the alkali washing tank into the separator tank. At this time, the mixed liquid enters the separator tank from the top of the separator tank, and the oil in the upper layer of the separator tank is mixed for the second time, and another mixing reaction is carried out. The oil in the upper layer of the separator tank can be purified again, and then the mixed liquid is allowed to stand in the separator tank for sedimentation and stratification, and the purified oil in the upper layer is sent to the oil product temporary storage tank 4; and the alkali solution at the bottom of the separator tank can be sent to the alkali solution regulating tank 5 for storage through the tank pouring pump and the corresponding pipeline. The treatment process of the above-mentioned alkali washing tank and the liquid separator tank is an intermittent operation rather than a continuous operation. Therefore, the inventor chooses to set the alkali washing tank and the liquid separator tank as two groups in parallel, so that the two groups can work alternately to achieve continuous treatment of the pyrolysis oil. When the output of the pyrolysis oil is small, only one group of alkali washing tanks and liquid separator tanks can be used, and the other group can be kept on standby for maintenance. At this time, it is only necessary to extend the residence time of the pyrolysis oil in the crude oil temporary storage tank 1 to meet the time interval between the operation of the alkali washing tank and the liquid separator tank.

[0044] After the above treatment, the water content of the oil product is reduced to below 0.5wt%, the inorganic chlorine removal rate reaches more than 95%, and it does not contain solid impurities.

[0045] Preferably, the bottom of the separator tank is also connected to the alkali liquid regulating tank 5 through a pipeline, so that the reacted alkali liquid stored in the alkali liquid regulating tank 5 can be sent back to the separator tank after sedimentation. When the oil in the separator tank is less and difficult to discharge from the top, this operation can increase the liquid level in the separator tank, so that the oil can be discharged more conveniently. At the same time, through the detection of the alkali liquid in the alkali liquid regulating tank 5, qualified alkali liquid can be sent back to the separator tank to participate in alkali washing again, thereby reducing the demand for fresh alkali liquid and reducing the processing cost.

[0046] Preferably, a heat-insulating heating layer is also provided in the liquid separation tank and the oil temporary storage tank 4 to maintain the internal temperature of the tank.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for separating and purifying cracked oil products, characterized in that: Here are the steps: First, the condensed pyrolysis oil is fed as raw material oil from the middle of a raw material oil temporary storage tank (1). The lower part of the raw material oil temporary storage tank (1) is provided with a liquid outlet, and the bottom part is provided with a solid residue outlet. The pyrolysis oil is stratified after sedimentation in the tank, and the solid residue is precipitated at the bottom of the tank. The middle layer is a mixture of water and a small amount of oil products, and the upper layer is oil products. The solid oil residue can be discharged for treatment by regular discharge through the solid residue outlet. The mixture of water and a small amount of oil products in the middle layer is discharged through the liquid outlet, enters an observation water tank (11) and is tested. If the oil content is too high, it re-enters the raw material oil temporary storage tank (1) with the newly introduced pyrolysis oil to enter and exit sedimentation. If the oil content is low, it can be directly sent to a water treatment process for treatment. The upper layer of the crude oil temporary storage tank (1) is sent to the alkali washing tank. The alkali washing tank is provided with a spraying device, which is connected to the fresh alkali solution storage tank (6) through a pipeline. The inorganic chlorine in the oil product is neutralized by spraying the alkali solution, so that it is transferred from the oil product to the alkali solution, thereby reducing the inorganic chlorine content in the oil product. A circulation pump is provided outside the alkali washing tank to realize the circulation spraying of the alkali solution. The alkali washing tank is connected to the liquid separation tank through a pipeline and a tank dumping pump. The specific working process of the tank dumping pump is as follows: when the volume of the alkali solution and the oil product in the alkali washing tank reaches 50-70% of the liquid level in the tank, the connection between the crude oil temporary storage tank (1) and the alkali washing tank is disconnected, the tank dumping pump and the first pipeline are turned on, and part of the mixed liquid of the alkali solution and the oil product is transferred to the liquid separation tank through the first pipeline. The alkali solution and the inorganic chlorine component in the oil product continue to react in the liquid separation tank; at this time, the remaining alkali in the alkali washing tank The mixed liquid of the liquid and the oil product continues to circulate in the alkali washing tank through the circulation pump; and the oil liquid after the reaction in the separation tank will separate into layers with the alkali liquid after standing, the oil liquid will gather in the upper layer, and the alkali liquid will gradually settle to the lower layer; when the reaction in the alkali washing tank reaches a certain time, the tank pouring pump and the second pipeline can be opened, and the alkali liquid in the lower layer of the separation tank will be sent back to the top of the alkali washing tank, and enter the spray device to continue to contact and react with the oil product; when the total time that all the oil products stay in the alkali washing tank reaches 20-30 minutes, the tank pouring pump and the first pipeline are opened, and all the mixed liquid in the alkali washing tank is sent to the separation tank, and the mixed liquid is allowed to stand and settle in the separation tank to separate into layers, and the purified oil product in the upper layer is sent to the oil product temporary storage tank (4); and the alkali liquid at the bottom of the separation tank can be sent to the alkali liquid regulating tank (5) for storage through the tank pouring pump and the corresponding pipeline.

2. The method for separating and purifying cracked oil according to claim 1, characterized in that: The crude oil temporary storage tank (1), the alkali washing tank, the liquid separation tank and the oil product temporary storage tank (4) are all provided with a heat preservation and heating layer.

3. The method for separation and purification of cracked oil according to claim 1, characterized in that: The alkali solution in the alkali washing tank is selected from a NaOH solution or a KOH solution with a mass concentration of 20-30%, and the flow ratio of the oil product to the alkali solution in the alkali washing tank is 2-4:1.

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