Sealed petroleum coke decoking system of delayed coking device

Abstract

The invention discloses a closed petroleum coke decoking system of a delayed coking device, which relates to the technical field of petrochemical engineering, and comprises a coke tower, a double-roller screening crusher, a box-type closed material taking conveyor, a material distributing machine, a coke storage dewatering bin, a coke breeze pool, a slurry pump and a tail gas treatment system, and the double-roller screening crusher is connected with a bottom cover machine at the bottom of the coke tower; the box-type closed material taking conveyor receives coke screened by the double-roller screening crusher, the box-type closed material taking conveyor, the material distributing machine and the coke storage dewatering bin are sequentially connected in a transmission mode, the coke breeze pool is connected with the box-type closed material taking conveyor, the coke breeze pool is connected with the coke storage dewatering bin through a slurry pump, and the tail gas treatment system comprises a tail gas inlet. Respective tail gas outlets of the coke tower, the box-type closed material taking conveyor, the coke powder tank and the coke storage dewatering bin are converged to a tail gas inlet of the tail gas treatment system through pipelines. The closed treatment of the whole process of decoking, coke taking, dehydration, storage and loading of the delayed coking device is realized, the unorganized emission of tail gas is effectively restrained, the tail gas is uniformly treated through the tail gas treatment system, and the industrial emission standard is finally met.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical engineering, and in particular to a closed decoking system for petroleum coke in a delayed coking unit. Background Art

[0002] The delayed coking process mostly adopts an open treatment process. The petroleum coke produced by the delayed coking unit is mostly piled in the open air, and the decoking, dehydration, coking, transportation, storage and loading processes are all open operations. During the operation, a mixed gas containing a large amount of water vapor, petroleum coke dust, VOCs (volatile organic compounds), sulfides and other foul-smelling and toxic substances is volatilized. This type of unorganized exhaust gas is produced in multiple processes and different locations of the delayed coking process. It has a complex composition, high temperature, and is difficult to recover. It seriously affects the surrounding atmospheric environment and endangers the health of operators. It is the main source of pollution for delayed coking units.

[0003] The current waste gas treatment technologies for delayed coking units are mostly aimed at treating the unorganized emissions generated by different processes and locations of delayed coking. There is a lack of a device system for unified recovery and centralized treatment of the unorganized emissions generated by the entire delayed coking process, which cannot meet the new emission standards and needs to be urgently resolved. Summary of the invention

[0004] The present application provides a closed decoking system for petroleum coke in a delayed coking unit, which solves the technical problem of treating unorganized exhaust gas emitted by delayed coking units in the current petrochemical industry.

[0005] The present application provides a closed decoking system for petroleum coke in a delayed coking unit, comprising a coke tower, a double-roll screening crusher, a box-type closed material taking conveyor, a material distributor, a coke storage and dehydration bin, a powder coke pool, a slurry pump and a tail gas treatment system, wherein the double-roll screening crusher is connected to a bottom cover machine at the bottom of the coke tower, the box-type closed material taking conveyor receives coke screened by the double-roll screening crusher, the box-type closed material taking conveyor, the material distributor and the coke storage and dehydration bin are sequentially connected for transmission, the powder coke pool is connected to the box-type closed material taking conveyor, the powder coke pool is connected to the coke storage and dehydration bin via a slurry pump, and the tail gas treatment system comprises a tail gas inlet, and respective tail gas outlets of the coke tower, the box-type closed material taking conveyor, the powder coke pool and the coke storage and dehydration bin are all collected to the tail gas inlet through pipelines.

[0006] The beneficial effects of the present application are as follows: a closed decoking system for petroleum coke in a delayed coking unit is provided. After hydraulic decoking, the coke blocks first fall from the coke tower into the double-roller screening crusher at the bottom of the coke tower. After crushing and screening, the coke is transported to the coke storage and dehydration bin via a box-type closed material taking conveyor and a placing machine. After entering the coke storage and dehydration bin, the coke is further allowed to stand and dehydrate, and the filtered water enters the coke cutting water system for recycling. The dehydrated coke is transported from the bottom of the coke storage and dehydration bin to the loading system via a discharging machine, wherein the powdered coke pool collects the coke powder slurry from the box-type closed material taking conveyor, and the slurry in the powdered coke pool is transported to the coke storage and dehydration bin for supplementary water via a slurry pump after being allowed to stand and settle to remove part of the coke powder. In the system, the tail gases of the coke tower, the box-type closed material taking conveyor, the powdered coke pool and the coke storage and dehydration bin are converged and converged to the tail gas treatment system. One treatment; In this system, closed settings are carried out at various locations, including the connection between the double-roller screening crusher and the coke tower, the transportation process of coke from crushing to coke storage and dehydration bin is designed in a closed manner, and the powder coke pool collects the powder slurry containing coke in the box-type closed material conveyor, so as to realize the closed treatment of the whole process of decoking, coking, dehydration, storage and loading of the delayed coking unit, effectively curbing unorganized emissions, no powder coke and VOCs are discharged, achieving minimum water vapor emissions, small water vapor losses, and meeting safety and environmental protection production requirements; if there is an extreme condition in which the coke tower discharges too much coke or water in an instant during the production process, the superimposed buffering effect of the volume of each component can also be used to effectively prevent gas overflow, thereby ensuring the continuous and stable operation of the closed petroleum coke treatment system; the tail gas is uniformly treated by the tail gas treatment system to ultimately meet the industry emission standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0008] Figure 1 An overall schematic diagram of a closed decoking system for petroleum coke in a delayed coking unit provided in the present application;

[0009] Figure 2 A detailed schematic diagram of a tail gas treatment system in a closed decoking system for petroleum coke in a delayed coking unit provided in the present application;

[0010] Figure 3 A detailed schematic diagram of a coke storage and dehydration bin in a closed decoking system for petroleum coke in a delayed coking unit provided in the present application;

[0011] Figure 4 for Figure 3 The view formed by looking down at the section at AA in the middle;

[0012] Figure 5 for Figure 3The view formed by looking down at the section at BB in the middle;

[0013] Figure 6 for Figure 3 Top view of the water filter assembly.

[0014] Figures are marked: 1-coke tower, 2-bottom cover machine, 3-double-roller screening crusher, 4-box-type closed material conveyor, 5-coke cutting water pump, 6-coke cutting water tank, 7-powder coke pool, 8-slurry pump, 9-distributor, 10-coke storage and dehydration bin, 11-exhaust gas treatment system, 12-coke cutting water lifting pump, 13-clear water tank, 14-discharging machine, 15-exhaust fan, 16-exhaust gas air cooler, 17-exhaust gas pretreatment tank, 18-washing water booster pump, 19-pretreatment Tank flushing water pump, 20-alkaline solution circulation pump, 21-washing water circulation pump, 22-washing water filter, 23-fresh water booster pump, 24-exhaust gas washing tower, 25-exhaust gas separation tank, 101-bin body, 1011-conical section, 1012-feeding port, 1013-exhaust gas collecting port of dehydration bin, 102-annular drain pipe, 103-water filter assembly, 1031-filter screen, 1032-reinforcement ribs, 104-sand filter grid internals, 1041-bars. DETAILED DESCRIPTION

[0015] Please refer to Figure 1 , discloses a closed decoking system for petroleum coke in a delayed coking device, comprising a coke tower 1, a double-roller screening crusher 3, a box-type closed material taking conveyor 4, a material distributor 9, a coke storage and dehydration bin 10, a powder coke pool 7, a slurry pump 8 and an exhaust gas treatment system 11. The double-roller screening crusher 3 is connected to a bottom cover machine 2 at the bottom of the coke tower 1. After hydraulic decoking, the coke blocks first fall from the coke tower 1 into the double-roller screening crusher 3 at the bottom of the coke tower 1. The box-type closed material taking conveyor 4 receives the coke screened by the double-roller screening crusher 3, such as Figure 1 Two coke drums 1 and corresponding double-roller screening crushers 3 are shown, and a box-type closed material reclaiming conveyor 4 can receive all the coke from the double-roller screening crushers 3.

[0016] The box-type closed material conveyor 4, the material distributor 9 and the coke storage and dehydration bin 10 are sequentially connected. The coke is delivered to the material distributor 9 through the box-type closed material conveyor 4, and is distributed to the coke storage and dehydration bin 10 through the material distributor 9. Figure 1 The two coke storage and dehydration bins 10 are shown in the figure. After the coke enters the coke storage and dehydration bin 10, it is further left to stand and dehydrated, and the filtered water enters the coke cutting water system for recycling. The dehydrated coke is transported from the bottom of the coke storage and dehydration bin 10 to the loading system through the discharger 14.

[0017] The powdered coke pool 7 is connected to the box-type closed material taking conveyor 4, and the powdered coke pool 7 is connected to the coke storage and dehydration bin 10 via a slurry pump 8. The powdered coke pool 7 collects the coke powder-containing slurry from the box-type closed material taking conveyor 4. The slurry in the powdered coke pool 7 is statically settled to remove part of the coke powder, and then transported to the coke storage and dehydration bin 10 via the slurry pump 8, and the coke storage and dehydration bin 10 is supplemented with water, thereby realizing the function of internal water storage and material receiving in the coke storage and dehydration bin 10.

[0018] Please refer to Figure 1 The tail gas treatment system 11 includes a tail gas inlet, and the tail gas outlets of the coke tower 1, the box-type closed material reclaiming conveyor 4, the fine coke pool 7 and the coke storage dehydration bin 10 are all collected to the tail gas inlet through pipelines. In this system, the tail gases of the coke tower 1, the box-type closed material reclaiming conveyor 4, the fine coke pool 7 and the coke storage dehydration bin 10 are collected and collected to the tail gas treatment system 11 for unified and safe treatment, and finally meet the industry emission standards.

[0019] In this system, all parts are sealed, including the connection between the double-roller screening crusher 3 and the coke drum 1, and the transportation process of coke from crushing to the coke storage and dehydration bin 10. The coke powder pool 7 is set to collect the coke powder slurry in the box-type closed material conveyor 4.

[0020] As a whole, this system realizes the closed processing of the whole process of decoking, coking, dehydration, storage and loading of the delayed coking unit, effectively curbs unorganized emissions, eliminates the emission of powdered coke and VOCs, achieves minimal water vapor emissions, and has low water vapor losses, thus meeting the requirements of safe and environmentally friendly production.

[0021] If an extreme condition occurs during the production process where the coke tower 1 instantly discharges too much coke or water, the superimposed buffering effect of the volumes of the various components can be used to effectively prevent gas overflow and ensure continuous and stable operation of the petroleum coke closed processing system.

[0022] In some embodiments, see Figure 1 The system also includes a clean water tank 13, a coke cutting water lifting pump 12, a coke cutting water tank 6 and a coke cutting water pump 5 which are connected in sequence. The clean water tank 13 is connected to the bottom of the coke storage and dehydration bin 10. The coke cutting water pump 5 is connected to the coke drum 1 through a pipeline to replenish water to the coke drum 1 and make full use of water resources.

[0023] In some embodiments, the rated processing capacity of the box-type enclosed material conveyor 4 is about 600 tons / hour. The coke is transported by a chain ring + scraper movement method, and the sprocket is driven by hydraulic drive. The initial dehydration of the coke is completed during the moving and conveying process, so that the moisture content of the outlet coke of the box-type enclosed material conveyor 4 is less than any value between 20% and 30%.

[0024] In some embodiments, please refer to Figures 3 to 6The coke storage and dehydration bin 10 includes a bin body 101, an annular drain pipe 102, a water filter assembly 103 and a sand filter grid internal 104. The bin body 101 is arranged in a cylindrical shape, and the main part of the bin body 101 is described as a main bin, and the lower part thereof is a conical section 1011, which is connected to the bottom end of the main bin, and the small end of the conical section 1011 is lower and the large end is higher in arrangement, and is arranged in an inverted manner. A feed port 1012 is arranged at the top of the bin body 101, and the feed port 1012 is opened at the center of the top of the bin body 101. A discharge port is arranged at the bottom of the bin body 101, and a discharge machine 14 is arranged at the discharge port. The dehydrated coke is fed to the loading system through the discharge machine 14, and the filtered water enters the coke cutting water system for recycling.

[0025] An annular drain pipe 102 is installed outside the conical section 1011 . The annular drain pipe 102 is concentrically arranged with the conical section 1011 . The annular drain pipe 102 is connected to the inner cavity of the conical section 1011 through a plurality of interfaces.

[0026] Please refer to Figure 3 and Figure 6 The water filter assembly 103 includes a plurality of water filter internals, which are evenly spaced in the circumferential direction of the bin body 101, and are installed on the inner wall of the bin body 101. The water filter internals are partially arranged along the axial direction of the main bin and partially arranged along the generatrix of the conical section 1011. The water filter assembly 103 is limited to be higher than the annular drain pipe 102. The water filter assembly 103 is mainly composed of a filter screen 1031, which is semi-cylindrical in shape as a whole. The water filter assembly 103 also includes the following: Figure 6 The reinforcing rib 1032 structure in the filter screen 1031 reinforces the filter screen 1031 .

[0027] Please refer to Figure 3 and Figure 4 The sand filter grid internals 104 are arranged horizontally in the silo 101, and are arranged below the feed port 1012. The sand filter grid internals 104 are arranged in a cone shape, and the feed port 1012 is directly opposite to the tip of the cone. The sand filter grid internals 104 are provided with bars 1041 arranged along the busbar from the center of the cone, and grid gaps are formed between adjacent bars 1041. The size of the grid gaps of the sand filter grid internals 104 gradually increases from the center of the cone to the outside.

[0028] The dehydration bin is used for separation of solid and liquid phases, and uses the gravity of solid materials to achieve closed discharge. The lower conical section 1011 of the bin body 101 stores water internally, and the water is stored to the upper end of the conical section to receive materials to buffer the kinetic energy of the lump coke entering the tank.

[0029] The lump coke enters the silo 101 from the feed port, and the material falls to the conical tip of the sand filter grid internals 104. The material moves outward and downward from the center of the cone, so that the material with a larger particle size passes through the sand filter grid internals 104 faster, while the material with a smaller particle size passes through the sand filter grid internals 104 slower. The material with a larger particle size first passes through the sand filter grid internals 104 until it falls on the water filter assembly 103, forming a layer of material with a larger particle size. The porous nature of the coke itself forms a "sand filter layer" with a certain liquid passage space. At the same time, the "sand filter" principle is used to intercept fine coke powder in the upper layer of large-particle coke blocks to achieve precision filtration, thereby controlling the particle size of coke powder in the filtered water to ≯3mm.

[0030] By using the principle of "sand filtration", the content of fine coke powder in the filtered water is reduced, which is beneficial to the normal operation of the filtered water delivery pump in the subsequent process; moreover, the unfavorable blockage of the filter screen 1031 in the filter assembly 103 is improved, and the normal operation of the filter screen 1031 in the filter assembly 103 is maintained. Overall, the overall water filtering efficiency of the dehydration bin is improved.

[0031] Please refer to Figures 3 to 6 By setting a water filter assembly 103 in the dehydration bin, the dehydration efficiency is improved, and the moisture content of the coke after dehydration is less than 8wt%. The water filter assembly 103 includes a filter screen 1031, which is semi-cylindrical, and the axial side of the semi-cylindrical filter screen is located on the inner wall of the bin body.

[0032] In addition, the closed tank-type coke storage and dehydration bin 10 provided in the present application has a fully closed working process of the dehydration bin, which can replace the traditional coke tank and grab bucket, save energy and protect the environment, reduce environmental pollution, and protect personnel safety.

[0033] Please refer to Figure 2 , Figure 2 The exhaust gas inlet where the above-mentioned points and devices converge is shown. In some embodiments, the exhaust gas treatment system 11 includes an exhaust gas fan 15, an exhaust gas pretreatment tank 17, an exhaust gas washing tower 24, an exhaust gas liquid separator 25 and a heating furnace. One end of the exhaust gas fan 15 is connected to the exhaust gas inlet, and the exhaust gas pretreatment tank 17 is connected to the inlet of the exhaust gas fan 15. The converged exhaust gas to be treated is collected and pressurized by the exhaust gas fan 15 and then sent to the exhaust gas pretreatment tank 17 along the pipeline. Optionally, an exhaust gas air cooler 16 is installed on the connecting pipeline between the exhaust gas fan 15 and the exhaust gas pretreatment tank 17 to cool the exhaust gas first.

[0034] A two-stage spray system is provided in the tail gas pretreatment tank 17. Figure 2 As shown, in the exhaust gas pretreatment tank 17, the exhaust gas is sprayed with water to remove dust and cool down, and the fine coke powder therein is removed. Figure 2 The two-stage spraying system is equipped with a pretreatment tank flushing water pump 19, one end of which is a fresh water inlet to provide water for spraying.

[0035] The exhaust gas outlet at the top of the exhaust gas pretreatment tank 17 is connected to the exhaust gas washing tower 24 through a pipeline. A water washing section, an alkali washing section, a spray section and a demister are arranged in the exhaust gas washing tower 24 from bottom to top. The exhaust gas is first washed once in the water washing section, and then the exhaust gas enters the alkali washing section for alkali washing to remove harmful gases. After spraying, the exhaust gas is defogged by the demister and output from the top of the exhaust gas washing tower 24.

[0036] An online monitor for H2S content is installed at the gas phase outlet pipeline at the top of the tail gas scrubber 24. The tail gas scrubber 24 is connected to the tail gas separator 25 after the online monitor for H2S content. The outlet of the tail gas separator 25 is connected to the heating furnace through the heating furnace fan. The H2S content of the purified tail gas is monitored by the online monitor for H2S, and the tail gas that meets the standards enters the tail gas separator 25 to separate the water vapor entrained in the tail gas. Finally, it is pressurized by the heating furnace fan and enters the heating furnace for incineration and harmless treatment.

[0037] In this way, the exhaust gas volume at the outlet is about 6000~8000Nm 3 / h, the outlet tail gas index is total sulfur content ≯30mg / m 3 , VOCs≯30mg / m 3 .

[0038] Please refer to Figure 2 The bottom of the tail gas pretreatment tank 17 is connected to the washing water booster pump 18, and the washing water booster pump 18 returns to the tail gas pretreatment tank 17 through a pipeline. The washing water booster pump 18 is equipped with a washing water outlet.

[0039] For the water washing section in the tail gas washing tower 24, please refer to Figure 2 The water washing section includes a water washing pipe with a liquid outlet, the water washing pipe part is arranged inside the tail gas washing tower 24, the water washing pipe is connected to the washing water circulation pump 21 and the washing water filter 22, and the washing water filter 22 is connected to the bottom of the tower body of the tail gas washing tower 24 through a pipeline.

[0040] For the alkali washing section in the tail gas washing tower 24, please refer to Figure 2 The alkali washing section includes an alkali washing pipe with a liquid outlet, the alkali washing pipe part is arranged inside the tail gas washing tower 24, one end of the alkali washing pipe is used as a fresh alkali liquid inlet, the tail gas washing tower 24 is provided with an alkali liquid collecting box at a middle position between the alkali washing pipe and the water washing pipe, the alkali liquid collecting box is connected to the alkali washing pipe through a pipeline via an alkali liquid circulation pump 20, and the pipeline connected to the alkali liquid circulation pump 20 is also provided with an alkali residue outlet;

[0041] For the spray section of the tail gas scrubber 24, please refer to Figure 2 , directly use the fresh water booster pump 23 outside the tower, connected to the fresh water inlet, to provide spraying water for the spraying section.

[0042] In summary, the above-mentioned closed decoking system for petroleum coke in the delayed coking unit can realize the closed processing of the whole process of decoking, coking, dehydration, storage and loading in the delayed coking unit, effectively curb unorganized emissions, no powdered coke and VOCs are discharged, and the minimum water vapor emission is achieved, with small water vapor loss, meeting the safety and environmental protection production requirements.

[0043] The rated processing capacity is about 600 tons / hour, the coke particle size is less than 200mm, the coke moisture content is less than 8wt%, the coke powder rate is less than 35wt%, the coke powder content in the coke cutting water is ≯800ppm(wt), the coke powder particle size is ≯3mm, and the total sulfur content in the tail gas after treatment is ≯30mg / m 3 、VOCs≯30mg / m 3 , not only meets the "GB 31570-2015 Petroleum Refining Industry Pollutant Emission Standard" (the standard requires H2S≯50mg / m 3 ; VOCs≯60mg / m 3 ), and the amount of waste gas is small, about 20% of other traditional closed decoking technologies.

[0044] In this system, the tail gas treatment system 11 removes dust and cools the tail gas, removes harmful gases, and reduces the water vapor entrained in the heating furnace tail gas through the tail gas pretreatment, water washing, and alkali washing processes.

[0045] In this system, the decoking, coke taking, conveying and dehydration systems are operated synchronously and continuously, with high production efficiency. This system can be fully automated, easy to operate, low labor intensity, the conveying equipment can be adjusted during operation, and the conveying capacity is large and the stability is high.

[0046] All electronic components and cables of this system are placed outdoors, the motor failure rate is low, inspection and maintenance are convenient, and the risk of fire and accidents is low.

[0047] If extreme conditions occur during the production process where too much coke or water is instantly discharged from the coke tower, the superimposed buffering effect of the volumes of each component can effectively prevent gas overflow and ensure continuous and stable operation of the closed petroleum coke processing system.

[0048] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0049] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A closed decoking system for petroleum coke in a delayed coking unit, characterized in that: include: A coke drum and a double-roller screening crusher, wherein the double-roller screening crusher is connected to a bottom cover machine at the bottom of the coke drum; A box-type enclosed material taking conveyor, a material distributor and a coke storage and dehydration bin, wherein the box-type enclosed material taking conveyor receives the coke screened by the double-roller screening crusher, and the box-type enclosed material taking conveyor, the material distributor and the coke storage and dehydration bin are sequentially connected for transmission; A powdered coke pool and a slurry pump, wherein the powdered coke pool is connected to the box-type closed material taking conveyor, and the powdered coke pool is connected to the coke storage and dehydration bin via the slurry pump; and The tail gas treatment system comprises a tail gas inlet, and the tail gas outlets of the coke drum, the box-type closed material taking conveyor, the fine coke pool and the coke storage and dehydration bin are all collected to the tail gas inlet through pipelines.

2. The closed decoking system for petroleum coke in a delayed coking unit according to claim 1, characterized in that: The tail gas treatment system comprises: An exhaust fan, one end of which is connected to the exhaust inlet; An exhaust gas pretreatment tank is connected to the inlet of the exhaust gas fan, and a two-stage spray system is arranged in the exhaust gas pretreatment tank; A tail gas washing tower is connected to the tail gas outlet at the top of the tail gas pretreatment tank, and a water washing section, an alkali washing section, a spray section and a demister are sequentially arranged in the tail gas washing tower from bottom to top, and a H2S content online monitor is arranged at the top gas phase outlet pipeline of the tail gas washing tower; The tail gas separator tank and the heating furnace, the tail gas washing tower is connected with the tail gas separator tank after the H2S content online monitor, the tail gas separator tank is used to separate the water vapor entrained in the tail gas, and the outlet of the tail gas separator tank is connected with the heating furnace through the heating furnace fan.

3. The closed decoking system for petroleum coke in a delayed coking unit according to claim 2, characterized in that: The two-stage spray system of the tail gas pretreatment tank is equipped with a pretreatment tank flushing water pump, one end of which is a fresh water inlet; The bottom of the tail gas pretreatment tank is connected to a washing water booster pump, and the washing water booster pump returns to the tail gas pretreatment tank through a pipeline. The washing water booster pump is equipped with a washing water outlet.

4. The closed decoking system for petroleum coke in a delayed coking unit according to claim 2, characterized in that: The water washing section of the tail gas washing tower comprises a water washing pipe with a liquid outlet, the water washing pipe is partially arranged inside the tail gas washing tower, the water washing pipe is connected to a washing water circulation pump and a washing water filter, and the washing water filter is connected to the bottom of the tower body of the tail gas washing tower through a pipeline; The alkali washing section of the tail gas washing tower comprises an alkali washing pipe with a liquid outlet, the alkali washing pipe is partially arranged inside the tail gas washing tower, one end of the alkali washing pipe serves as a fresh alkali liquid inlet, the tail gas washing tower is provided with an alkali liquid collecting box at a middle position between the alkali washing pipe and the water washing pipe, the alkali liquid collecting box is connected to the alkali washing pipe through a pipeline via an alkali liquid circulation pump, and the pipeline connected to the alkali liquid circulation pump is also provided with an alkali residue outlet; The spray section of the tail gas scrubber includes a fresh water booster pump located outside the tower.

5. The closed decoking system for petroleum coke in a delayed coking unit according to claim 2, characterized in that: An exhaust gas air cooler is installed on the connecting pipe between the exhaust gas fan and the exhaust gas pretreatment tank.

6. The closed decoking system for petroleum coke in a delayed coking unit according to any one of claims 1 to 5, characterized in that: The box-type closed material conveyor uses a chain ring and a scraper to transport coke, and completes the initial dehydration of coke during the moving and transporting process, so that the moisture content of the outlet coke of the box-type closed material conveyor is less than any value between 20% and 30%.

7. The closed decoking system for petroleum coke in a delayed coking unit according to claim 6, characterized in that: The coke storage and dehydration bin comprises: A bin body, the bin body comprising a main bin and a conical section located at the bottom of the main bin, a material inlet is provided at the center of the top of the bin body, and a material outlet is provided at the center of the bottom of the bin body; An annular drain pipe is concentrically mounted on the outer wall of the tapered section, and the annular drain pipe is connected to the inner cavity of the tapered section through a plurality of interfaces; A water filter assembly, comprising a plurality of water filter inner parts, the plurality of water filter inner parts are evenly spaced in the circumferential direction of the bin body, the water filter inner parts are mounted on the inner wall of the bin body, and the water filter inner parts are partially arranged along the axial direction of the main bin and partially arranged along the generatrix of the tapered section; and The sand filter grid internals are arranged transversely in the bin body, the sand filter grid internals are arranged in a cone shape, the feed inlet is directly opposite to the cone tip of the cone, the sand filter grid internals are provided with bars arranged along the busbar from the cone center, and grid gaps are formed between adjacent bars, and the grid gaps of the sand filter grid internals gradually increase in size from the cone center toward the outside.

8. The closed decoking system for petroleum coke in a delayed coking unit according to claim 7, characterized in that: After passing through the coke storage and dehydration bin, the moisture content of the coke is controlled to be less than 8wt%, and the particle size of the coke powder in the filtered water of the coke storage and dehydration bin is controlled to be ≯3mm.

9. The closed decoking system for petroleum coke in a delayed coking unit according to claim 8, characterized in that: The outlet tail gas volume after being treated by the tail gas treatment system is 6000~8000Nm 3 / h, the outlet tail gas index is total sulfur content ≯30mg / m 3 , VOCs≯30mg / m 3 .

10. The closed decoking system for petroleum coke in a delayed coking unit according to claim 1, characterized in that: The closed decoking system for petroleum coke in the delayed coking unit also includes a clear water tank, a coke cutting water lift pump, a coke cutting water tank and a coke cutting water pump which are connected in sequence. The clear water tank is connected to the bottom of the coke storage and dehydration bin, and the coke cutting water pump is connected to the coke tower through a pipeline.

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