Method and apparatus for coking fine benzene secondary treatment

Abstract

The application discloses a device for secondary treatment of refined heavy benzene in coking, which comprises a debenzene tower, a refined heavy benzene tank, a refined heavy benzene self-flow pipeline, a refined heavy benzene pump, a refined heavy benzene branch pipeline and a lower-stage condensate tank which are connected in sequence; the lower-stage condensate tank is connected with a lower-stage liquid return pipeline, a lower-stage liquid seal tank and a lower-stage liquid return pipeline at one end, and is connected with a full-flow pipeline, an upper-stage cold liquid tank at the other end; the lower-stage condensate tank is connected with a lower-stage condensing inlet pipeline, a lower-stage cold liquid pump, a lower-stage condensate outlet pipeline and a primary cooler at one end; the upper-stage cold liquid tank is connected with an upper-stage liquid return pipeline, an upper-stage liquid seal tank and an upper-stage liquid return pipeline at one end, and is connected with an upper-stage condensate inlet pipeline, an upper-stage condensate pump, an upper-stage condensate outlet pipeline and a primary cooler at the other end. The application also discloses a method for secondary treatment of refined heavy benzene in coking. The device uses the existing primary cooler in coking to treat the refined heavy benzene with many impurities produced in the crude benzene process, and recovers light benzene and toluene in the refined heavy benzene for secondary use.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metallurgical coking gas purification, in particular to a method and device for secondary treatment of refined heavy benzene produced in the process of coking crude benzene. BACKGROUND

[0002] At present, many coking enterprises adopt washing oil to wash benzene, refined heavy benzene and naphthalene in coking oven gas to recover high-value substances and products in the gas. In the crude benzene process, the washing oil and the benzene group organic matter and naphthalene are directly contacted in the benzene washing tower to make the benzene group organic matter and naphthalene dissolved in the washing oil, and then the benzene group organic matter and naphthalene are separated in the benzene removal tower to achieve the purpose of recovering light benzene, refined heavy benzene and naphthalene. In the distillation section of the benzene removal tower, the 180-185℃ washing oil rich in benzene group organic matter and naphthalene enters from the middle of the benzene removal tower from top to bottom, and the 180-190℃ steam enters from the bottom from bottom to top. The steam and the washing oil are inversely contacted in the benzene removal tower to separate the benzene group organic matter and naphthalene from the washing oil. The separated benzene group organic matter and naphthalene form a gas phase and rise upward with the steam to form a mixed gas. In the distillation section of the benzene removal tower, the temperature of the mixed gas decreases layer by layer. According to the boiling point temperature of various substances, naphthalene and refined heavy benzene are collected. Finally, light benzene is used as reflux at the top of the tower to strictly control the temperature of the mixed gas at the top of the tower at 78-80℃. The light benzene is condensed into liquid light benzene by a condenser, and then separated by a separator to recover valuable light benzene. The naphthalene and refined heavy benzene collected in the middle and upper part are condensed by the change of temperature. Such control mode determines that the purity of the collected naphthalene and refined heavy benzene is not high, and the quality cannot be effectively controlled. At present, most of the coking enterprises adopt the two-benzene tower process to produce light benzene and refined heavy benzene, and a small part of the enterprises directly produce crude benzene (i.e. a mixture of light benzene and refined heavy benzene).

[0003] At present, the naphthalene and refined heavy benzene produced by the two-benzene tower are respectively collected as products in the process design. The naphthalene is periodically returned to the tar tank and mixed into the tar to be sold as a tar product. The refined heavy benzene is directly sold as a product. Due to the limitation of the process, the purity of the collected refined heavy benzene is not high, and a large amount of naphthalene, washing oil light components and water are often contained. As a product, the quality is low, the price is low, and the yield is small. At present, many coking enterprises directly return the refined heavy benzene to the tar tank and mix it into the tar to be sold as a tar product. Such treatment method is relatively simple, but due to the high temperature of the tar, which reaches 80-90℃, part of the refined heavy benzene will volatilize and be lost during storage, increasing the cost of tail gas treatment. SUMMARY

[0004] The present application provides a method and device for secondary treatment of coking refined heavy benzene, which utilizes the existing equipment of the coking industry to treat the refined heavy benzene with many impurities produced in the process of crude benzene, and recycles the light benzene and toluene in the refined heavy benzene for secondary use.

[0005] The device for secondary treatment of coking refined heavy benzene comprises a debenzene tower, a refined heavy benzene tank, a refined heavy benzene self-flow pipeline, a refined heavy benzene pump, a refined heavy benzene branch pipeline and a lower-stage condensate tank which are connected in sequence.

[0006] The debenzene tower is provided with a rich oil inlet at the side and a lean oil outlet at the bottom, and is provided with a direct steam inlet at the bottom and a benzene vapor outlet at the top.

[0007] The refined heavy benzene tank is provided with a pressurized nitrogen gas pipeline, and the refined heavy benzene pipeline is communicated with the original pipeline to the oil depot.

[0008] The primary cooler is provided with a circulating water inlet at the side and a circulating water outlet at the top, and is provided with a low-temperature water inlet at the bottom and a low-temperature water outlet at the side.

[0009] The method for secondary treatment of coking refined heavy benzene comprises the following steps:

[0010] 1) The refined heavy benzene containing light components of washing oil, naphthalene and water is periodically delivered into the lower-stage condensate tank of the primary cooler by the refined heavy benzene pump, mixed with the condensate in the lower-stage condensate tank, and then the mixed condensate is sent into the primary cooler by the lower-stage condensate pump to clean and cool the gas, and the condensate is sprayed in the lower-stage condensate tank through the lower-stage liquid seal tank;

[0011] 2) During the cleaning and cooling of the gas, the water, tar and part of the naphthalene in the gas are condensed and cleaned, the condensate in the lower-stage condensate tank is increased, and when the condensate accumulates to the full-flow port of the lower-stage condensate tank, the excess condensate flows into the upper-stage condensate tank;

[0012] 3) The condensate is sent to the upper section of the primary cooler by the upper section condensate pump, and is directly contacted with the gas at a temperature of 78-82°C in the upper section of the primary cooler. During the cleaning and cooling of the gas by the condensate, the moisture, tar and part of the naphthalene in the gas are cleaned and removed. The condensate flows back to the upper section condensate tank through the upper section liquid seal tank to be recycled and sprayed. The amount of the upper section condensate is increased, and when the liquid level reaches a certain value, the excess condensate is sent to the circulating ammonia water system through the bypass pipe.

[0013] 4) The refined heavy benzene remaining in the condensate is sent to the circulating ammonia water system and is sent back to the coke oven gas collecting pipe with the ammonia water to cool the raw coke oven gas at a temperature of 1100-1150°C.

[0014] In the step 1), the temperature of the condensate in the lower section condensate tank is 21-23°C.

[0015] In the step 3), the temperature of the condensate in the upper section condensate tank is 35-42°C. The upper section condensate at a temperature of 35-42°C is sent to the upper section of the primary cooler by the upper section condensate pump, and is directly contacted with the gas at a temperature of 78-82°C in the upper section of the primary cooler.

[0016] In the step 3), the upper section condensate is sent to the circulating ammonia water system through the bypass pipe of the upper section condensate pump.

[0017] In the step 4), the benzene group organic matter is heated by the high-temperature gas and is re-vaporized into the gas.

[0018] Advantages: Compared with the prior art, the present application has the following advantages: the present application uses the existing equipment of the primary cooler in the coking process to perform secondary treatment on the impurity-containing crude benzene produced in the crude benzene process. The refined heavy benzene is not only subjected to secondary treatment, but also is not returned to the tar tank as a component of the tar, thereby reducing the use value of the refined heavy benzene. On the one hand, the light aromatic substances in the refined heavy benzene are recovered, the benzene content in the gas is increased, and the light benzene yield in the crude benzene process is increased. On the other hand, the refined heavy benzene is mixed into the condensate in the primary cooler as an organic solvent, thereby improving the flowability and solubility of the condensate. As a result, the condensate plays a cleaning role on the tar and naphthalene on the surface of the cooling pipe in the primary cooler, thereby reducing the resistance of the primary cooler, reducing the energy consumption, and reducing the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The structure of the present application Figure One ;

[0020] Figure 2 The structure of the present application Figure Two ;

[0021] 1 is a benzene stripping tower; 2 is a refined heavy benzene pump; 3 is a lower section condensate tank; 4 is a lower section condensate inlet pipe; 5 is a lower section condensate pump; 6 is a full-flow pipe; 7 is an upper section condensate tank; 8 is an upper section condensate inlet pipe; 9 is an upper section condensate pump; 10 is an upper section condensate outlet pipe; 11 is a primary cooler; 12 is an upper section return liquid pipe; 13 is a lower section condensate outlet pipe; 14 is a lower section return liquid pipe; 15 is an upper section return liquid pipe; 16 is an upper section liquid seal tank; 17 is a lower section liquid seal tank; 18 is a lower section return liquid pipe; 19 is a refined heavy benzene branch pipe; 20 is a refined heavy benzene pipe; 21 is a refined heavy benzene gravity flow pipe; and 22 is a refined heavy benzene tank. DETAILED DESCRIPTION

[0022] The technical solutions of the present application are described in further detail below in combination with the drawings and the specific embodiments.

[0023] The present application mainly performs secondary treatment on refined heavy benzene produced by a crude benzene process through existing primary cooling equipment of a coking plant. The refined heavy benzene collected by the crude benzene process is collected, and the collected refined heavy benzene is regularly sent to a primary cooler lower section condensate tank through an existing refined heavy benzene shield pump, and the refined heavy benzene is returned into the condensate as a main component of the spraying liquid, and then is sent into the primary cooler through a condensate pump to cool the coal gas. During the cooling process of the coal gas at 78-82℃, the refined heavy benzene is heated and partially volatilized, and the light components benzene and toluene are mixed into the coal gas and enter the subsequent benzene washing process, thereby increasing the light benzene yield. The heavy components xylene and the like are integrated with the mixed liquid as the spraying liquid. Due to the characteristics of benzene, the benzene plays a cleaning role on the tar and naphthalene on the surface of the cooling pipe in the primary cooler, thereby reducing the resistance of the primary cooler, reducing energy consumption, and reducing production cost.

[0024] The present application utilizes the original coking crude benzene process from the refined heavy benzene pump to the oil depot process pipeline, and a branch pipe is introduced to the lower section condensate tank of the primary cooler, and a regulating valve is installed. The refined heavy benzene pump is used to periodically deliver the refined heavy benzene into the lower section condensate tank, and mix with the condensate in the lower section condensate tank, and the temperature of the mixed condensate is 21-23℃. In the lower section of the primary cooler, the lower section condensate pump is used to send the condensate in the lower section condensate tank into the primary cooler lower section to clean and cool the gas, and the lower section gas temperature is about 42-45℃, and in the cooling process, part of the light components of the refined heavy benzene will volatilize and mix into the gas. After the condensate is mixed into the refined heavy benzene, due to the high-efficiency organic solvent effect of the refined heavy benzene, the refined heavy benzene is easy to dissolve the organic matters such as tar and naphthalene, and the flowability and solubility of the condensate are increased, and the tar and sundries accumulated on the surface of the heat exchange pipe of the primary cooler are effectively removed, and the cooling effect of the primary cooler is increased. In the process of cleaning and cooling the gas, the water, tar and part of the naphthalene in the gas are condensed and cleaned, and the condensate in the lower section condensate tank is gradually increased, and after the accumulated condensate reaches the full-flow port of the lower section condensate tank, the excess 21-23℃ condensate will flow into the upper section condensate tank. In the upper section condensate tank, the upper section condensate temperature is 35-42℃, and after mixing with the lower section condensate containing the refined heavy benzene, the flowability and solubility are better, and the volatility is stronger, and the 35-42℃ upper section condensate is sent into the upper section of the primary cooler by the upper section condensate pump, and directly contacts with the 78-82℃ gas in the upper section of the primary cooler, and due to the temperature rise, the light components of the refined heavy benzene in the condensate volatilize and mix into the gas, and the benzene content in the gas is increased, and the light benzene yield of the subsequent benzene washing process is improved. The 78-82℃ gas in the upper section of the primary cooler is cooled to 42-45℃, and in the process of being cleaned and cooled by the condensate, the water, tar and part of the naphthalene in the gas are cleaned, and the upper section condensate is gradually increased, and after reaching a certain liquid level, the excess condensate is sent to the circulating ammonia water system through the bypass pipe. After the residual refined heavy benzene in the condensate is sent to the circulating ammonia water system, it is sent back to the coke oven gas collecting pipe with the ammonia water to cool the 1100-1150℃ raw gas, and due to the heating of the high-temperature gas, the benzene organic matters are re-volatilized into the gas, and the effective components are not lost. The lower section condensate mixed with the refined heavy benzene is easy to dissolve the organic matters such as tar and naphthalene due to the high-efficiency organic solvent effect of the refined heavy benzene, and the flowability and solubility of the condensate are increased, and the tar and sundries accumulated on the surface of the heat exchange pipe of the primary cooler are effectively removed, and the cooling effect of the primary cooler is increased.

[0025] The processing device of the present application comprises a refined benzene tank 21, a refined benzene pump 2, a lower section condensate tank 3, a lower section condensate pump 5, an upper section condensate tank 7, an upper section condensate pump 9, a primary cooler 11, and connecting pipes, valves and the like between the devices. The processing process of the present application mainly utilizes the refined benzene pipeline 20 from the refined benzene pump 2 to the oil depot in the original coking crude benzene process, a refined benzene branch pipeline 19 is introduced to the lower section condensate tank 3 of the primary cooler 11, and an adjusting valve is installed. The refined benzene is periodically delivered into the lower section condensate tank 3 by the refined benzene pump 2, mixed with the condensate in the lower section condensate tank 3, and the temperature of the mixed condensate is 21-23℃. In the lower section of the primary cooler 11, the condensate in the lower section condensate tank 3 is sent into the lower section of the primary cooler 11 by the lower section condensate pump 5 to clean and cool the coal gas, and the condensate is then circulated and sprayed by the lower section liquid seal tank into the lower section condensate tank 3, the temperature of the lower section coal gas is about 42-45℃, and part of the light components of the refined benzene will volatilize and mix into the coal gas in the cooling process. After the condensate is mixed into the refined benzene, the refined benzene can easily dissolve organic matters such as tar and naphthalene due to the high-efficiency organic solvent of the refined benzene, the flowability and solubility of the condensate are increased, and the tar and sundries accumulated on the surface of the heat exchange pipe of the primary cooler 11 are effectively removed, and the cooling effect of the primary cooler 11 is improved. In the process of cleaning and cooling the coal gas, the water, tar and part of the naphthalene in the coal gas are condensed and cleaned, the condensate in the lower section condensate tank 3 gradually increases, and when the condensate accumulates to the full-flowing port of the lower section condensate tank 3, the excess condensate at 21-23℃ will flow into the upper section condensate tank 7.

[0026] In the upper section condensate tank 7, the temperature of the upper section condensate is 35-42℃, and after being mixed with the lower section condensate containing the refined benzene, the flowability, solubility and volatility of the upper section condensate are further improved, the upper section condensate at 35-42℃ is sent into the upper section of the primary cooler 11 by the upper section condensate pump 9, and directly contacts with the coal gas at a temperature of 78-82℃. Due to the temperature rise, part of the refined benzene in the condensate volatilizes and mixes into the coal gas, the benzene content in the coal gas is increased, and the light benzene yield of the subsequent benzene washing process is improved. However, the coal gas at 78-82℃ in the upper section of the primary cooler 11 is cooled to 42-45℃, and in the process of being cleaned and cooled by the condensate, the water, tar and part of the naphthalene in the coal gas are cleaned, the condensate is then circulated and sprayed by flowing back to the upper section condensate tank 7 through the upper section liquid seal tank 16, the upper section condensate gradually increases, and when the liquid level reaches a certain level, the excess condensate is sent to the circulating ammonia water system through the bypass pipe. After the residual refined benzene in the condensate is sent to the circulating ammonia water system, the refined benzene is sent back to the coke oven gas collecting pipe with the ammonia water to cool the raw coal gas at 1100-1150℃, and due to the heating of the high-temperature coal gas, the benzene organic matters are re-volatilized into the coal gas, and the effective components are not lost.

[0027] The present application is suitable for the treatment of refined heavy benzene produced by the benzene diphenyl tower of the present coking plant. The present application can well solve the problem that the refined heavy benzene cannot be used as a single product due to the oil and naphthalene content and high moisture content, avoid the treatment mode of low-cost back-mixing tar tank, maximize the benzene content in the coal gas, increase the light benzene yield of the benzene washing process, and improve the composition of the initial cooling liquid, which can greatly reduce the resistance of the initial cooler, improve the cooling effect of the initial cooler.

[0028] The present application treats the back-mixing of the initial cooling condensate tank containing impurities. According to the calculation of 1.1 million tons of coke gas per year, the monthly production of refined heavy benzene is 60-80 tons, which contains part of naphthalene and other impurities. After secondary treatment, 60%-70% of the refined heavy benzene is converted into light benzene, and the light benzene yield is increased by about 42-56 tons. The monthly increase in benefits is: 42 tons x 8000 yuan / ton = 336,000 yuan. The back-mixing of the refined heavy benzene condensate tank is used as a condensate, which greatly improves the quality of the condensate, increases the flowability and solubility, reduces the resistance of the initial cooler, improves the heat exchange efficiency, thereby reducing the consumption of circulating water and low-temperature water, saving energy consumption, reducing the equipment maintenance cost of the initial cooler, and further improving the benefits.

Claims

1. An apparatus for secondary treatment of coking refined heavy benzene, characterized in that: The system includes a benzene stripping tower (1), a refined heavy benzene tank (22), a refined heavy benzene gravity flow pipeline (21), a refined heavy benzene pump (2), a refined heavy benzene branch pipeline (19), and a lower condensate tank (3) connected in sequence. The refined heavy benzene pump (2) is connected to the refined heavy benzene pipeline (20). One path of the lower condensate tank (3) is connected to the lower return pipe A (18), the lower liquid seal tank (17), the lower return pipe B (14), and the primary cooler (11). One path of the lower condensate tank (3) is connected to the full flow pipe (6) and the upper condensate tank (7). One path of the lower condensate tank (3) is connected to the lower condensate inlet pipe (4) and the lower condensate pump (5). The lower section condensate outlet pipe (13) and the primary cooler (11) are connected; the upper section condensate tank (7) is connected to the upper section return pipe A (15), the upper section liquid seal tank (16), the upper section return pipe B (12), and the primary cooler (11) in one direction, and to the upper section condensate inlet pipe (8), the upper section condensate pump (9), the upper section condensate outlet pipe (10), and the primary cooler (11) in another direction; the condensate in the upper section condensate tank (7) is sent to the upper section of the primary cooler (11) through the upper section condensate pump (9), and directly contacts the gas at a temperature of 78℃-82℃ in the upper section of the primary cooler (11).

2. The apparatus for secondary treatment of coking refined heavy benzene according to claim 1, characterized in that: The benzene stripping tower (1) is provided with a rich oil inlet on the side and a lean oil outlet at the bottom. The benzene stripping tower (1) is provided with a direct steam inlet at the bottom and a benzene vapor outlet at the top. The benzene stripping tower (1) is provided with a reflux light benzene inlet at the top and a fine heavy benzene stream outlet on the side.

3. The apparatus for secondary treatment of coking refined heavy benzene according to claim 1, characterized in that: The refined heavy benzene tank (22) is equipped with a pressurized nitrogen pipe, and the refined heavy benzene pipeline (20) is connected to the original pipeline to the oil depot.

4. The apparatus for secondary treatment of coking refined heavy benzene according to claim 1, characterized in that: The primary cooler (11) is provided with a circulating water inlet on the side and a circulating water outlet at the top. The primary cooler (11) is provided with a low temperature water inlet at the bottom and a low temperature water outlet on the side. The primary cooler (11) is provided with an 80°C gas inlet at the top and a 21°C gas outlet at the bottom. The excess condensate from the upper condensate outlet pipe (10) is sent to the external circulating ammonia water system.

5. A method for secondary treatment of coking refined heavy benzene using the apparatus for secondary treatment of coking refined heavy benzene according to any one of claims 1-3, characterized in that: Includes the following steps: 1) The coking-containing light components of wash oil, naphthalene and water are periodically transported to the lower section condensate tank (3) of the primary cooler (11) by the heavy benzene pump (2) and mixed with the condensate in the lower section condensate tank (3). The mixed condensate is then sent to the lower section of the primary cooler (11) for cleaning and cooling of the gas by the lower section condensate pump (5). The condensate enters the lower section condensate tank (3) through the lower section liquid seal tank (17) for circulation spraying. 2) During the cleaning and cooling process of the gas, the moisture, tar and some naphthalene in the gas will be condensed and cleaned off. The amount of condensate in the lower section condensate tank (3) will increase. After the condensate accumulates to the full flow port of the lower section condensate, the excess condensate will flow into the upper section condensate tank (7). 3) The condensate is sent to the upper section of the primary cooler (11) through the upper section condensate pump (9). In the upper section of the primary cooler (11), it comes into direct contact with the coal gas at a temperature of 78℃-82℃. During the process of the coal gas being cleaned and cooled by the condensate, the moisture, tar and some naphthalene in the coal gas will be washed off. The condensate flows back to the upper section condensate tank (7) through the upper section liquid seal tank (16) for circulation spraying. The amount of condensate in the upper section increases. After reaching a certain liquid level, the excess condensate is sent to the circulating ammonia water system through the bypass pipe. 4) The remaining refined heavy benzene in the condensate is sent to the circulating ammonia system, and then sent back to the coke oven gas collecting pipe with the ammonia to cool the raw coal gas at 1100℃-1150℃.

6. The method for secondary treatment of coking refined heavy benzene according to claim 5, characterized in that: In step 1), the temperature of the condensate in the lower section condensate tank (3) is 21℃-23℃.

7. The method for secondary treatment of coking refined heavy benzene according to claim 5, characterized in that: In step 3), the temperature of the condensate in the upper condensate tank (7) is 35℃-42℃.

8. The method for secondary treatment of coking refined heavy benzene according to claim 5, characterized in that: In step 3), the upper section condensate is sent to the circulating ammonia system via the bypass pipe of the upper section condensate pump (9).

9. The method for secondary treatment of coking refined heavy benzene according to claim 5, characterized in that: In step 4), the benzene group organic compounds are heated by the high-temperature coal gas and then volatilize back into the coal gas.

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