Tar distillate dephenolization system and method with oil-containing phenate treatment capacity

Abstract

The invention discloses a tar distillate dephenolization system with oil-containing phenate treatment capacity. The tar distillate dephenolization system comprises a first naphthalene oil extraction tower and a second naphthalene oil extraction tower communicated with the first naphthalene oil extraction tower through a convection unit, a raw material feeding unit and a crude phenate output pipeline are arranged on the first naphthalene oil extraction tower; an alkaline phenate feeding unit and a dephenolized naphthalene oil output pipeline are arranged on the second naphthalene oil extraction tower. The invention also discloses a tar distillate dephenolization method with oil-containing phenate treatment capability. The oil-containing phenolate is treated during the operation period of the tar distillate dephenolization process, the phenolate and the dephenolized naphthalene oil in the oil-containing phenolate are separated and are respectively recovered to the phenolate and the dephenolized naphthalene oil for resource utilization, and the normal operation of a dephenolization device is not influenced.

Description

Technical Field

[0001] The invention relates to a tar distillation process in the coking industry, and more particularly to a tar-based fraction dephenolization system and method capable of treating oil-containing phenol salts. Background Art

[0002] The existing tar-based fraction dephenolization process mainly dephenolizes the naphthalene oil or three mixed fractions in the tar distillation process, and produces the process of dephenolized naphthalene oil or washed three mixed fractions. In actual production, the dephenolized naphthalene oil or washed three mixed fractions should be placed for separation before entering the naphthalene distillation process, and part of the phenolate solution is separated to avoid blocking the tower plate, heat exchanger and furnace tube in the subsequent naphthalene distillation process, so as to achieve the purpose of delaying the shutdown cleaning cycle. However, the separated oil-containing phenolate solution is more difficult to handle, and if it is discharged, it will form pollution, and if it directly enters the phenol refining process, it will cause the crude phenol neutral oil to be high, and if it is allocated with naphthalene oil or three mixed fractions to enter the dephenolization process, it will easily cause the dephenolization process pipeline to be blocked or the feed pump to be frequently cavitated.

[0003] At present, the tar distillation process in the coking industry in China has a tar fraction dephenolization process with oily phenol salt treatment, which is used to recover the oily phenol salt solution, eliminate environmental pollution, and reduce adverse effects on downstream processes, but it is rarely mentioned.

[0004] For example, selected from the journal "Chemical Management" (October 2014) "Improvement and Application of Continuous Alkaline Washing and Phenol Removal Process of Tri-mixed Naphthalene Oil" (authors Wang Huan, Jiang Shuyan, Xue Ruzhong, Zhao Fei, Coking Plant of Laiwu Branch of Shandong Iron and Steel Group). This article studies and analyzes the problems existing in the operation of the continuous alkaline washing and phenol removal unit of tri-mixed naphthalene oil, and improves the process according to the analysis results to improve the separation effect of the medium in the continuous washing tower, reduce energy consumption, and reduce the generation of industrial wastewater.

[0005] Selected from the journal "Fuel and Chemical Industry" (January 2012) "Renovation of Continuous Washing Process of Naphthalene Oil Fraction" (Wu Jun'an, Chai Gaogui, Shanxi Coking Group Co., Ltd.), this article points out that Shanxi Coking Group Co., Ltd. has newly built a 300,000 t / a coal tar processing unit, and the following problems have occurred in production. 1) The processing volume of the naphthalene oil washing process does not match the naphthalene oil output of tar distillation. The designed processing volume of naphthalene oil washing is 4.1m 3 / h, the naphthalene oil output when tar distillation is running at full load is 6~6.5m 3 / h. 2) The mixing mode of the 1# washing tower is not suitable for washing naphthalene oil fraction. The 1# washing tower is a convection mixing tower. Naphthalene oil and dilute alkali enter the tower from the bottom and top of the clarifier respectively. The two media are in contact through natural convection through the distributor to react and remove phenol. In actual production, naphthalene oil easily enters the phenol salt system, blocks the phenol salt pipeline, and causes system chaos. 3) The residence time of the naphthalene oil fraction in the system is too short.

[0006] Improvements: 1. Change the natural convection phenol removal after entering the tower in the original process to the mixing process before entering the tower. Use a mixer to fully mix the two media, simplify the process flow. After the naphthalene oil single fraction cut from tar distillation reacts with dilute alkali for phenol removal and then is further distilled and separated into phenol oil, methyl naphthalene oil, and 95% naphthalene oil, the washing reaction effect is improved. 2. Optimize the design and transformation of the naphthalene oil injector for washing industrial naphthalene fraction. After the transformation, the processing capacity of naphthalene oil washing meets the full-load requirement of tar processing.

[0007] For another example, Chinese Patent Application No. 201420605788.4 discloses a device for reducing the phenol and phenate content in de-phenolized naphthalene oil, belonging to the technical field of chemical separation. The device for reducing the phenol and phenate content in de-phenolized naphthalene oil includes a naphthalene oil feeding mechanism connected to a naphthalene oil tank; an alkali-phenol extraction mechanism connected to the naphthalene oil feeding mechanism; a first naphthalene oil extraction tower connected to the naphthalene oil feeding mechanism; a de-phenolized naphthalene oil conveying mechanism connected to the first naphthalene oil extraction tower; a dilute alkali conveying mechanism connected to the de-phenolized naphthalene oil conveying mechanism; a second naphthalene oil extraction tower connected to the de-phenolized naphthalene oil conveying mechanism; and the second naphthalene oil extraction tower is connected to the alkali-phenol extraction mechanism. The device for reducing the phenol and phenate content in de-phenolized naphthalene oil of the present invention improves the washing and phenol removal treatment capacity of naphthalene oil and improves the quality of de-phenolized naphthalene oil.

[0008] For another example, Chinese Patent Application No. 201821058913.9 discloses an overflow device for reducing the amount of phenate in raw material de-phenolized naphthalene oil, including a first oil storage tank, a second oil storage tank, an overflow pipeline, and a pump feeding device. The upper parts of the first oil storage tank and the second oil storage tank are connected by an interconnected overflow pipeline. The top of the first oil storage tank is connected to a feed pipeline, and the feed pipeline is connected to a downcomer. The downcomer vertically extends from the upper side of the first oil storage tank to the bottom of the first oil storage tank. The lower part of the second oil storage tank is connected to a discharge pipeline, and the discharge pipeline is connected to the pump feeding device. The present invention increases the static precipitation time of de-phenolized naphthalene oil in the first oil storage tank by using the overflow pipeline in the upper parts of the first and second oil storage tanks, thereby reducing the phenate entrained in the de-phenolized naphthalene oil sent to the device and improving the stability of the naphthalene distillation device system.

[0009] Although the above-mentioned disclosed literatures improve the phenol removal efficiency of naphthalene oil (or three-component mixed oil) and reduce the entrainment amount of phenate in de-phenolized naphthalene oil in different ways, they do not involve the treatment of the oil-containing phenate separated after the subsequent storage and static stratification of de-phenolized naphthalene oil. Summary of the Invention

[0010] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a tar-based fraction dephenolization system and method with the ability to treat oil-containing phenolate, treat the oil-containing phenolate during the operation of the tar-based fraction dephenolization process, separate the phenolate and dephenolized naphthalene oil therein, respectively recover them into phenolate and dephenolized naphthalene oil for resource utilization, and not affect the normal operation of the dephenolization device.

[0011] To achieve the above purpose, the present invention adopts the following technical solutions:

[0012] In the first aspect of the present invention, a tar-based fraction dephenolization system with the ability to treat oil-containing phenolate is provided, including a first naphthalene oil extraction tower and a second naphthalene oil extraction tower connected to the first naphthalene oil extraction tower through a convection unit;

[0013] A raw material feeding unit and a crude phenolate output pipeline are provided on the first naphthalene oil extraction tower;

[0014] An alkaline phenolate feeding unit and a dephenolized naphthalene oil output pipeline are provided on the second naphthalene oil extraction tower.

[0015] Preferably, the raw material feeding unit includes a naphthalene oil feeding pipeline connected to the first naphthalene oil extraction tower, a fifth mixer provided on the naphthalene oil feeding pipeline, and a first oil-containing phenolate feeding pipeline connected to the fifth mixer.

[0016] Preferably, the alkaline phenolate feeding unit includes a second dephenolized naphthalene oil pipeline connected to the second naphthalene oil extraction tower, a first mixer and a second mixer provided on the second dephenolized naphthalene oil pipeline and arranged in sequence along the medium flow direction;

[0017] The second mixer is connected to the upper section of the second naphthalene oil extraction tower;

[0018] An alkali liquor feeding pipeline is connected to the first mixer;

[0019] A second oil-containing phenolate feeding pipeline is connected to the second mixer.

[0020] Preferably, the convection unit includes a first dephenolized naphthalene oil pipeline and an alkaline phenolate pipeline;

[0021] The first dephenolized naphthalene oil pipeline connects the first naphthalene oil extraction tower and the second naphthalene oil extraction tower, and the medium flow direction is from the first naphthalene oil extraction tower to the second naphthalene oil extraction tower;

[0022] The alkaline phenolate pipeline connects the first naphthalene oil extraction tower and the second naphthalene oil extraction tower, and the medium flow direction is from the second naphthalene oil extraction tower to the first naphthalene oil extraction tower;

[0023] A third mixer and a fourth mixer are arranged in sequence along the medium flow direction on the first dephenolized naphthalene oil pipeline;

[0024] Both the third mixer and the fourth mixer are connected to the second naphthalene oil extraction column;

[0025] A third oil-containing phenolate feed pipeline is connected to the fourth mixer.

[0026] Preferably, the crude phenolate output pipeline is connected to the lower section of the first naphthalene oil extraction column;

[0027] The dephenolated naphthalene oil output pipeline is connected to the upper section of the second naphthalene oil extraction column.

[0028] In a second aspect of the present invention, there is provided a method for dephenolizing tar-based fractions with the ability to treat oil-containing phenolate. The following steps are achieved by using the tar-based fraction dephenolization system with the ability to treat oil-containing phenolate provided in the first aspect of the present invention:

[0029] The naphthalene oil in the naphthalene oil feed pipeline and the oil-containing phenolate in the first oil-containing phenolate feed pipeline enter the fifth mixer for mixing, and are sent to the lower distribution tray of the first naphthalene oil extraction column. The second naphthalene oil extraction column sends the alkaline phenolate to the upper distribution tray of the first naphthalene oil extraction column through the alkaline phenolate pipeline. The naphthalene oil and the alkaline phenolate are in countercurrent contact in the first naphthalene oil extraction column, so that the phenol in the naphthalene oil becomes phenolate;

[0030] The first naphthalene oil extraction column sends the dephenolated naphthalene oil to the second naphthalene oil extraction column through the first dephenolated naphthalene oil pipeline;

[0031] The second dephenolated naphthalene oil pipeline sends the dephenolated naphthalene oil in the second naphthalene oil extraction column to the first mixer, mixes it with the NaOH solution fed into the lye feed pipeline, and then mixes it with the oil-containing phenolate in the second mixer, and enters the upper clarifier of the second naphthalene oil extraction column.

[0032] Preferably, the medium entering the third mixer is composed of the dephenolated naphthalene oil in the first naphthalene oil extraction column and a part of the dephenolated naphthalene oil flowing out from the upper clarifier of the second naphthalene oil extraction column.

[0033] The tar-based fraction dephenolization system and method with the ability to treat oil-containing phenolate provided by the present invention can treat the oil-containing phenolate during the operation of the tar-based fraction dephenolization process, separate the phenolate and dephenolated naphthalene oil therein, and recover them to the phenolate and dephenolated naphthalene oil respectively for resource utilization, and does not affect the normal operation of the dephenolization device. In particular, it is a tar-based fraction dephenolization process with the ability to treat oil-containing phenolate in the tar distillation process system of the petroleum processing industry and the coking industry. When implementing the treatment of oil-containing crude phenolate, the tar-based fraction dephenolization process can maintain normal production. Compared with the prior art, only some pipelines and valves are added, and the investment in transformation is very small, which is very economically feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the framework structure of the tar fraction dephenolization system of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] In order to better understand the above technical solutions of the present invention, the technical solutions of the present invention will be further described below with reference to the drawings and embodiments.

[0036] Combined with Figure 1 As shown, a tar fraction dephenolization system with the ability to treat oil-containing phenolic salts provided by the present invention includes a first naphthalene oil extraction tower 1 and a second naphthalene oil extraction tower 2 connected to the first naphthalene oil extraction tower 1 through a convection unit.

[0037] A raw material feeding unit and a crude phenolic salt output pipeline 12 are provided on the first naphthalene oil extraction tower 1.

[0038] An alkaline phenolic salt feeding unit and a dephenolized naphthalene oil output pipeline 14 are provided on the second naphthalene oil extraction tower 2.

[0039] The raw material feeding unit includes a naphthalene oil feeding pipeline 8 connected to the first naphthalene oil extraction tower 1, a fifth mixer 7 provided on the naphthalene oil feeding pipeline 8, and a first oil-containing phenolic salt feeding pipeline 9 connected to the fifth mixer 7.

[0040] The alkaline phenolic salt feeding unit includes a second dephenolized naphthalene oil pipeline 15 connected to the second naphthalene oil extraction tower 2, a first mixer 3 and a second mixer 4 provided on the second dephenolized naphthalene oil pipeline 15 and arranged in sequence along the medium flow direction.

[0041] The second mixer 4 is connected to the upper section of the second naphthalene oil extraction tower 2.

[0042] An alkali liquor feeding pipeline 13 is connected to the first mixer 3.

[0043] A second oil-containing phenolic salt feeding pipeline 10 is connected to the second mixer 4.

[0044] The convection unit includes a first dephenolized naphthalene oil pipeline 16 and an alkaline phenolic salt pipeline 17.

[0045] The first dephenolized naphthalene oil pipeline 16 is connected between the first naphthalene oil extraction tower 1 and the second naphthalene oil extraction tower 2, and the medium flow direction is from the first naphthalene oil extraction tower 1 to the second naphthalene oil extraction tower 2.

[0046] The alkaline phenolic salt pipeline 17 is connected between the first naphthalene oil extraction tower 1 and the second naphthalene oil extraction tower 2, and the medium flow direction is from the second naphthalene oil extraction tower 2 to the first naphthalene oil extraction tower 1.

[0047] A third mixer 5 and a fourth mixer 6 are arranged in sequence along the medium flow direction on the first dephenolized naphthalene oil pipeline 16.

[0048] The third mixer 5 and the fourth mixer 6 are both connected to the second naphthalene oil extraction column 2.

[0049] A third oil-containing phenolate feed pipeline 11 is connected to the fourth mixer 6.

[0050] The crude phenolate output pipeline 12 is connected to the lower section of the first naphthalene oil extraction column 1;

[0051] The dephenolated naphthalene oil output pipeline 14 is connected to the upper section of the second naphthalene oil extraction column 2.

[0052] Refer again to Figure 1 As shown, the present invention also provides a method for dephenolizing tar-based fractions with the ability to treat oil-containing phenolate, and the following steps are achieved by using the tar-based fraction dephenolizing system of the present invention:

[0053] The raw material is tar-based fractions, mainly including: naphthalene oil, three-component mixture, etc.

[0054] The raw material (naphthalene oil, three-component mixture, etc., hereinafter referred to as naphthalene oil) is pumped into the fifth mixer 7 at the required flow rate by the naphthalene oil feed pipeline 8 and the oil-containing phenolate in the first oil-containing phenolate feed pipeline 9, and sent to the lower distribution tray of the first naphthalene oil extraction column 1. The alkaline phenolate is sent to the upper distribution tray of the first naphthalene oil extraction column 1 by the second naphthalene oil extraction column 2 through the alkaline phenolate pipeline 17. The naphthalene oil and the alkaline phenolate are in countercurrent contact in the first naphthalene oil extraction column 1, so that the phenol in the naphthalene oil becomes phenolate.

[0055] The first naphthalene oil extraction column 1 sends the dephenolated naphthalene oil to the second naphthalene oil extraction column 2 through the first dephenolated naphthalene oil pipeline 16. To keep the liquid level in the second naphthalene oil extraction column 2 unchanged, the extraction amount is adjusted. After the extraction amount of the dephenolated naphthalene oil reaches the specified value, it enters the third mixer 5. The medium entering the third mixer 5 is composed of the dephenolated naphthalene oil in the first naphthalene oil extraction column 1 and a part of the dephenolated naphthalene oil flowing out from the upper clarifier of the second naphthalene oil extraction column 2. The alkaline phenolate is supplied by the upper receiving small tank, introduced into the third mixer 5 to contact the dephenolated naphthalene oil, and then mixed with the oil-containing phenolate in the fourth mixer 6, and enters the lower clarifier of the second naphthalene oil extraction column 2. The liquid level in the clarifier is controlled by the liquid level regulator. The discharged dephenolated naphthalene oil is sent to the first mixer 3 by a pump, and the flow rate sent is approximately equal to the flow rate loaded into the third mixer 5.

[0056] The second dephenolized naphthalene oil pipeline 15 sends the dephenolized naphthalene oil in the second naphthalene oil extraction tower 2 to the first mixer 3, where it is mixed with the NaOH solution fed through the lye feed pipeline 13. Then, it is mixed with the oil-containing phenolate in the second mixer 4 and enters the upper clarifier of the second naphthalene oil extraction tower 2. The dephenolized naphthalene oil flows into the dephenolized naphthalene oil intermediate tank from the upper overflow port. A part of it returns to the dephenolized naphthalene oil circulation pump to maintain the feed flow rate of the mixer. The dephenolized naphthalene oil intermediate tank maintains a certain liquid level, and the excess dephenolized naphthalene oil is continuously pumped to the dephenolized naphthalene oil tank through the dephenolized naphthalene oil output pipeline 14.

[0057] The route for the oil-containing phenolate to enter the system can be one or more points among the second mixer 4, the fourth mixer 6, and the fifth mixer 7.

[0058] Example 1

[0059] The raw material is naphthalene oil with a naphthalene content of 75%, a methylnaphthalene content of 11%, and a phenol content of 2%, and the flow rate is 6.5 m 3 / h. The composition of the oil-containing phenolate is 35% phenolate solution and 65% dephenolized naphthalene oil. The oil-containing phenolate enters the system through the fifth mixer 7, and the flow rate is 0.6 m 3 / h. After separation, the dephenolized naphthalene oil contains 0.4% phenol, and the phenolate contains a trace amount of oil (less than 0.2%).

[0060] Example 2

[0061] The raw material is naphthalene oil with a naphthalene content of 75%, a methylnaphthalene content of 11%, and a phenol content of 2%, and the flow rate is 6.5 m 3 / h. The composition of the oil-containing phenolate is 35% phenolate solution and 65% dephenolized naphthalene oil. The oil-containing phenolate enters the system through the second mixer 4, the fourth mixer 6, and the fifth mixer 7, and the flow rate is 1.8 m 3 / h, flowing evenly into each mixer. After separation, the dephenolized naphthalene oil contains 0.4% phenol, and the phenolate contains a trace amount of oil (less than 0.2%).

[0062] Those of ordinary skill in the art in this technical field should recognize that the above examples are only used to illustrate the present invention and are not intended to limit the present invention. As long as it is within the scope of the essential spirit of the present invention, changes and modifications to the above-described examples will fall within the scope of the claims of the present invention.

Claims

1. A tar-based fractionated phenol removal system with the ability to handle oil-containing phenolate, characterized in that: It includes a first naphthalene oil extraction tower and a second naphthalene oil extraction tower connected to the first naphthalene oil extraction tower through a convection unit; A raw material feeding unit and a crude phenolate output pipeline are provided on the first naphthalene oil extraction tower; An alkaline phenolate feeding unit and a dephenolized naphthalene oil output pipeline are provided on the second naphthalene oil extraction tower.

2. The phenol removal system for tar-based fractions with the ability to treat oil-containing phenol salts according to claim 1, characterized in that: The raw material feeding unit includes a naphthalene oil feeding pipeline connected to the first naphthalene oil extraction tower, a fifth mixer provided on the naphthalene oil feeding pipeline, and a first oil-containing phenolate feeding pipeline connected to the fifth mixer.

3. The tar-based fractionated phenol removal system with the ability to treat oil-containing phenolate according to claim 1, characterized in that: The alkaline phenolate feeding unit includes a second dephenolized naphthalene oil pipeline connected to the second naphthalene oil extraction tower, a first mixer and a second mixer provided on the second dephenolized naphthalene oil pipeline and arranged in sequence along the medium flow direction; The second mixer is connected to the upper section of the second naphthalene oil extraction tower; An alkali liquor feeding pipeline is connected to the first mixer; A second oil-containing phenolate feeding pipeline is connected to the second mixer.

4. The tar-based fractionated phenol removal system with the ability to treat oil-containing phenolate according to claim 1, characterized in that: The convection unit includes a first dephenolized naphthalene oil pipeline and an alkaline phenolate pipeline; The first dephenolized naphthalene oil pipeline connects the first naphthalene oil extraction tower and the second naphthalene oil extraction tower, and the medium flow direction is from the first naphthalene oil extraction tower to the second naphthalene oil extraction tower; The alkaline phenolate pipeline connects the first naphthalene oil extraction tower and the second naphthalene oil extraction tower, and the medium flow direction is from the second naphthalene oil extraction tower to the first naphthalene oil extraction tower; A third mixer and a fourth mixer are provided on the first dephenolized naphthalene oil pipeline in sequence along the medium flow direction; Both the third mixer and the fourth mixer are connected to the second naphthalene oil extraction tower; A third oil-containing phenolate feeding pipeline is connected to the fourth mixer.

5. The tar-based fraction dephenolization system with the ability to treat oil-containing phenolate according to claim 1, characterized in that: The crude phenolate output pipeline is connected to the lower section of the first naphthalene oil extraction tower; The dephenolized naphthalene oil output pipeline is connected to the upper section of the second naphthalene oil extraction tower.

6. A method for removing phenol from a tar-based fraction with the ability to treat oil-containing phenolate, characterized in that, The following steps are realized by using the tar-based fraction dephenolization system with the ability to process oil-containing phenolate as described in any one of claims 1-5: The naphthalene oil in the naphthalene oil feeding pipeline and the oil-containing phenolate in the first oil-containing phenolate feeding pipeline enter the fifth mixer for mixing, and are sent to the lower distribution tray of the first naphthalene oil extraction tower. The second naphthalene oil extraction tower sends the alkaline phenolate to the upper distribution tray of the first naphthalene oil extraction tower through the alkaline phenolate pipeline. The naphthalene oil and the alkaline phenolate are in countercurrent contact in the first naphthalene oil extraction tower, so that the phenol in the naphthalene oil becomes phenolate; The first naphthalene oil extraction tower sends the dephenolized naphthalene oil to the second naphthalene oil extraction tower through the first dephenolized naphthalene oil pipeline; The second dephenolized naphthalene oil pipeline sends the dephenolized naphthalene oil in the second naphthalene oil extraction tower to the first mixer, mixes it with the NaOH solution fed into by the alkali liquor feeding pipeline, and then mixes it with the oil-containing phenolate in the second mixer, and enters the upper clarifier of the second naphthalene oil extraction tower.

7. The method for removing phenol from tar fractions with the ability to treat oil-containing phenolate according to claim 6, characterized in that: The medium entering the third mixer is composed of the dephenolized naphthalene oil in the first naphthalene oil extraction tower and a part of the dephenolized naphthalene oil flowing out from the upper clarifier of the second naphthalene oil extraction tower.

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