Near-zero-emission fine desulfurization device and method for liquid hydrocarbon alkaline residues

Abstract

The invention belongs to the technical field of liquid hydrocarbon desulfurization, and particularly relates to a near-zero-emission fine desulfurization device and method for liquid hydrocarbon alkaline residues, the device comprises an amine washing organic sulfur reactor and an alkaline washing organic sulfur reactor, one side of the amine washing organic sulfur reactor is communicated with a liquid hydrocarbon raw material pipe and a lean amine liquid pipe; the amine washing organic sulfur reactor is communicated with an amine washing separation tank, the amine washing separation tank is communicated with the alkali washing organic sulfur reactor, one side of the alkali washing organic sulfur reactor is further communicated with an alkali liquor pipe, and the alkali washing organic sulfur reactor is communicated with an alkali washing separation tank; and the alkali washing separation tank is connected with a refined liquid hydrocarbon pipe. According to the method, hydrogen sulfide and carbonyl sulfide in the liquid hydrocarbon are removed by adopting an organic sulfur reactor and compound amine liquid extraction, and then mercaptan in the liquid hydrocarbon is removed to below 5mg / m < 3 > by adopting the organic sulfur reactor and alkali liquid extraction. The total sulfur of the refined liquid hydrocarbon can be ensured to be below 10mg / m < 3 >, and the near-zero emission of the alkaline residues can be ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid hydrocarbon desulfurization, and particularly relates to a near-zero-emission fine desulfurization device and method for liquid hydrocarbon caustic sludge. Background Art

[0002] During the production of natural gas in oil and gas fields, most of them have liquid hydrocarbon by-products. For the desulfurization and refining process of liquid hydrocarbons recovered from oil and gas fields, a double-desulfurization process of using MDEA (methyldiethanolamine) amine solution to extract hydrogen sulfide and sodium hydroxide caustic solution to extract mercaptan is generally adopted. The rich amine solution after adsorbing hydrogen sulfide is regenerated by reducing the pressure and heating to 120 - 130 °C. After adding a small amount of sulfonated titanium phthalocyanine cobalt catalyst to the mercaptan-removing caustic solution, it is heated to 50 - 60 °C and sent to the oxidation tower to introduce air for catalytic oxidation. Mercaptan sodium is oxidized to form disulfide and sodium hydroxide, and then the disulfide is removed by sedimentation in the disulfide separation tank and back-extracted with solvent oil to remove the disulfide. The regenerated caustic solution is recycled for liquid hydrocarbon extraction to remove mercaptan. The amine solution and caustic solution extraction equipment are generally packed towers or fiber membrane contactors.

[0003] The above double-desulfurization process can only remove hydrogen sulfide and mercaptan in liquid hydrocarbons. For materials containing carbonyl sulfide, it is difficult to meet the requirements of fine desulfurization of liquid hydrocarbons, and it is only necessary to increase the design of solid hydrolysis and adsorption equipment for removing carbonyl sulfide; the caustic washing to remove mercaptan and the solvent back-extraction process require the use of back-extraction solvents, and acidic impurities such as phenols entrained in the solvents will increase the consumption of caustic solution and the discharge amount of caustic sludge; for liquid hydrocarbons with a high mercaptan content, the mercaptan-removing caustic solution requires a large amount of oxidation air, and carbon dioxide in the air will also increase the consumption of caustic solution and the discharge amount of caustic sludge.

[0004] Therefore, the existing liquid hydrocarbon desulfurization process has problems such as the need for back-extraction solvent conditions, a large amount of caustic solution oxidation tail gas, a large consumption of caustic solution, and a large discharge amount of caustic sludge. Summary of the Invention

[0005] In order to solve the above technical problems existing in the prior art, the present invention provides a near-zero-emission fine desulfurization device and method for liquid hydrocarbon caustic sludge. Specifically for liquid hydrocarbons containing sulfur in the forms of hydrogen sulfide, carbonyl sulfide, mercaptan, etc., an organic sulfur reactor and a compound amine solution oil extraction are used to remove hydrogen sulfide and carbonyl sulfide in the liquid hydrocarbon, as well as most of the mercaptan. Then, an organic sulfur reactor and a caustic solution extraction are used to remove the remaining small amount of mercaptan. The regeneration of the mercaptan-removing caustic solution adopts a packed tower air oxidation and nitrogen stripping to remove disulfide, and the regenerated caustic solution is used for liquid hydrocarbon circulating fine desulfurization. The purpose of realizing fine desulfurization of liquid hydrocarbons and near-zero emission of caustic sludge is achieved.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A near-zero emission fine desulfurization device for liquid hydrocarbon alkali residue, comprising an amine-washing organic sulfur reactor and an alkali-washing organic sulfur reactor. One side of the amine-washing organic sulfur reactor is connected to a liquid hydrocarbon raw material pipe and a lean amine liquid pipe; the amine-washing organic sulfur reactor is connected to an amine-washing separation tank, the amine-washing separation tank is connected to the alkali-washing organic sulfur reactor, and one side of the alkali-washing organic sulfur reactor is also connected to an alkali liquid pipe. The alkali-washing organic sulfur reactor is connected to an alkali-washing separation tank; the alkali-washing separation tank is connected to a refined liquid hydrocarbon pipe.

[0008] Further, the amine-washing organic sulfur reactor is installed on the amine-washing separation tank through a flange.

[0009] Further, a deammoniation coalescer separator is also arranged in the amine-washing separation tank, and the deammoniation coalescer separator is arranged at the rear side of the amine-washing separation tank.

[0010] Further, one side of the rear side of the amine-washing separation tank is connected to the alkali-washing organic sulfur reactor through an amine-washed liquid hydrocarbon pipe, and the bottom of the rear side of the amine-washing separation tank is connected to a rich amine liquid pipe.

[0011] Further, the alkali-washing organic sulfur reactor is installed on the alkali-washing separation tank through a flange. A de-alkali coalescer separator is also arranged in the alkali-washing separation tank, and the de-alkali coalescer separator is arranged at the rear side of the alkali-washing separation tank.

[0012] Further, the rear side of the alkali-washing separation tank is connected to a refined liquid hydrocarbon pipe, and the rear side of the alkali-washing separation tank is also connected to a rich alkali liquid pipe.

[0013] Furthermore, the near-zero emission fine desulfurization device for liquid hydrocarbon alkali residue further comprises an alkali liquid regeneration tower. The alkali liquid regeneration tower is connected to the rich alkali liquid pipe, and the alkali liquid flowing out of the alkali liquid regeneration tower flows into the alkali-washing organic sulfur reactor through the alkali liquid pipe.

[0014] Furthermore, an oxidation zone and a stripping zone are arranged in the alkali liquid regeneration tower. The oxidation zone and the stripping zone are distributed left and right and are connected above the oxidation zone and the stripping zone; the rich alkali liquid pipe is connected to the bottom of the oxidation zone, and the alkali liquid pipe is connected to the bottom of the stripping zone.

[0015] Furthermore, an air distributor and an oxidation packing zone are distributed from bottom to top in the oxidation zone, and the air distributor is connected to an air inlet pipe.

[0016] Furthermore, an alkali liquid heater and a catalyst injector are sequentially arranged on the rich alkali liquid pipe, and the catalyst injector is used for injecting a mercaptan desulfurization catalyst into the rich alkali liquid pipe.

[0017] Furthermore, a nitrogen distributor and a stripping packing zone are distributed from bottom to top in the stripping zone, and the nitrogen distributor is connected to a nitrogen inlet pipe.

[0018] Furthermore, an alkali solution cooler and an alkali solution pump are sequentially arranged on the alkali solution pipe, and an alkali solution supplement pipe is communicated between the alkali solution cooler and the alkali solution pump.

[0019] The present invention also provides a method for precise desulfurization of liquid hydrocarbon alkali residue with near-zero emissions, which adopts the above-mentioned device for precise desulfurization of liquid hydrocarbon alkali residue with near-zero emissions, and specifically includes:

[0020] S1. Pass the sulfur-containing liquid hydrocarbon into the amine-washing organic sulfur reactor through the liquid hydrocarbon raw material pipe, and at the same time pass the lean amine solution into the amine-washing organic sulfur reactor through the lean amine solution pipe. The liquid hydrocarbon undergoes amine-washing desulfurization treatment through the amine-washing organic sulfur reactor and the amine-washing separation tank.

[0021] S2. The liquid hydrocarbon after amine-washing desulfurization is passed into the alkali-washing organic sulfur reactor, and at the same time the alkali solution is passed into the alkali-washing organic sulfur reactor, and further desulfurization treatment is carried out through the alkali-washing organic sulfur reactor and the alkali-washing separation tank.

[0022] Furthermore, after the desulfurization treatment in step S2, the rich alkali solution flowing out of the alkali-washing separation tank is subjected to desulfurization treatment through the alkali solution regeneration tower, so that the contents of sodium mercaptide and disulfide in the alkali solution are controlled within a set range.

[0023] Furthermore, before entering the alkali solution regeneration tower, the rich alkali solution is heated to 50 - 65 °C.

[0024] Furthermore, before entering the alkali solution regeneration tower, a desulfurization catalyst is introduced into the rich alkali solution, so that the concentration of the desulfurization catalyst in the rich alkali solution is controlled within 100 - 200 ppm.

[0025] Furthermore, the lean amine solution is composed of a compound of UDS desulfurizer and MDEA (methyldiethanolamine), wherein the mass ratio of the UDS desulfurizer is 5%, the mass ratio of MDEA is 45%, and the remaining components are demineralized water or softened water.

[0026] Furthermore, the lean amine solution passed into the amine-washing organic sulfur reactor is 60 - 120% of the mass flow rate of the liquid hydrocarbon.

[0027] Furthermore, in step S2, the mass flow rate ratio of the alkali solution passed into the alkali-washing organic sulfur reactor to the liquid hydrocarbon is 10 - 50%.

[0028] Furthermore, the concentration of sodium hydroxide in the alkali solution is not less than 5%, and the temperature of the alkali solution is controlled at 30 - 45 °C.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The liquid hydrocarbon caustic residue near-zero emission fine desulfurization device and method provided by the present invention are directed at liquid hydrocarbons containing sulfur in the forms of hydrogen sulfide, carbonyl sulfide, mercaptan, etc. An organic sulfur reactor and a compounded amine solution of UDS desulfurizer and MDEA are used to extract and remove hydrogen sulfide and carbonyl sulfide from the liquid hydrocarbon, and at the same time, more than 80% of the mercaptan can be removed; then an organic sulfur reactor and caustic extraction are used to remove the mercaptan in the liquid hydrocarbon to less than 5 mg / m3; a coalescer separator composed of a distribution orifice plate and a knitted wire mesh is installed in the amine washing and caustic washing separation tank, which can remove the free water phase entrained in the liquid hydrocarbon after amine washing or caustic washing; the regeneration of the mercaptan caustic solution uses a packed tower air oxidation and nitrogen stripping to remove disulfides, and the contents of mercaptan sodium and disulfides in the regenerated caustic solution can be controlled below 100 ppm, which can ensure that the regenerated caustic solution maintains a high desulfurization capacity in a long cycle. The technology of the present invention can ensure that the total sulfur in the refined liquid hydrocarbon is below 10 mg / m3 and the caustic residue is near-zero emission. Description of the Drawings

[0031] Figure 1 It is a structural block diagram of the device of the present invention.

[0032] Figure 2 It is a schematic structural diagram of the liquid film inner core in the amine washing organic sulfur reactor of the present invention.

[0033] Figure 3 It is a schematic structural diagram of the orifice plate of the liquid film inner core in the amine washing organic sulfur reactor of the present invention.

[0034] Figure 4 It is a schematic structural diagram of the distribution orifice plate of the deamination coalescer separator of the present invention.

[0035] Figure 5 It is a schematic structural diagram of the knitted wire mesh and the hinge point of the deamination coalescer separator of the present invention.

[0036] Description of the Reference Numerals:

[0037] 1. Amine washing organic sulfur reactor, 2. Amine washing separation tank, 3. Deamination coalescer separator, 4. Caustic washing organic sulfur reactor, 5. Caustic washing separation tank, 6. Decausticization coalescer separator, 7. Caustic solution regeneration tower, 8. Oxidation packing area, 9. Air distributor, 10. Stripping packing area, 11. Nitrogen distributor, 12. Caustic solution pump, 13. Caustic solution heater, 14. Caustic solution cooler, 15. Catalyst injector, 16. Orifice plate, 17. Inner sleeve, 18. Fiber bundle, 19. Fiber bundle lifting hook, 20. Fiber bundle lifting hole;

[0038] 21. Liquid hydrocarbon feed pipe, 22. Liquid hydrocarbon pipe after amine washing, 23. Refined liquid hydrocarbon pipe, 24. Lean amine liquid pipe, 25. Rich amine liquid pipe, 26. Rich alkali liquid pipe, 27. Alkali liquid pipe, 28. Alkali liquid make-up pipe, 29. Spent alkali liquid pipe, 30. Air inlet pipe, 31. Nitrogen inlet pipe, 32. Tail gas pipeline, 33. Distribution orifice plate, 34. High molecular fiber, 35. Stainless steel wire. Detailed implementation manners

[0039] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps described in these embodiments and numerical expressions should not be construed as limiting the scope of the present invention.

[0041] The following description of the exemplary embodiments is merely illustrative and in no way restricts the present invention and its application or use. Technologies, methods, and devices known to those of ordinary skill in the relevant fields may not be discussed in detail here, but when applicable, these technologies, methods, and devices should be regarded as part of this specification.

[0042] The present invention provides a liquid hydrocarbon alkali residue near-zero emission fine desulfurization device, as Figure 1 shown, including an amine washing organic sulfur reactor 1 and an alkali washing organic sulfur reactor 4. One side of the amine washing organic sulfur reactor 1 is connected to a liquid hydrocarbon feed pipe 21 and a lean amine liquid pipe 24; the amine washing organic sulfur reactor 1 is connected to an amine washing separation tank 2, the amine washing separation tank 2 is connected to the alkali washing organic sulfur reactor 4, and one side of the alkali washing organic sulfur reactor 4 is also connected to an alkali liquid pipe 27. The alkali washing organic sulfur reactor 4 is connected to an alkali washing separation tank 5; the alkali washing separation tank 5 is connected to a refined liquid hydrocarbon pipe 23. The liquid hydrocarbon alkali residue near-zero emission fine desulfurization device further includes an alkali liquid regeneration tower 7. The alkali liquid regeneration tower 7 is connected to a rich alkali liquid pipe 26, and the alkali liquid flowing out of the alkali liquid regeneration tower 7 flows into the alkali washing organic sulfur reactor 4 through the alkali liquid pipe 27.

[0043] The amine washing organic sulfur reactor 1 is installed on the amine washing separation tank 2 through a flange. A deammoniation coalescer 3 is further arranged in the amine washing separation tank 2, and the deammoniation coalescer 3 is arranged at the rear side of the amine washing separation tank 2. One side of the rear side of the amine washing separation tank 2 is connected to the alkali washing organic sulfur reactor 4 through a liquid hydrocarbon pipe 22 after amine washing, and the bottom of the rear side of the amine washing separation tank 2 is connected to a rich amine liquid pipe 25.

[0044] The caustic scrubbing organic sulfur reactor 4 is installed on the caustic scrubbing separation tank 5 through a flange. A caustic removal coalescer 6 is further arranged in the caustic scrubbing separation tank 5, and the caustic removal coalescer 6 is arranged at the rear side of the caustic scrubbing separation tank 5. A refined liquid hydrocarbon pipe 23 is connected to the rear side of the caustic scrubbing separation tank 5, and a rich caustic liquid pipe 26 is also communicated with the rear side of the caustic scrubbing separation tank 5.

[0045] Among them, the amine scrubbing organic sulfur reactor 1 and the caustic scrubbing organic sulfur reactor 4 are mass transfer devices of the same type. A liquid film inner core is arranged inside the amine scrubbing organic sulfur reactor 1. The liquid film inner core is as Figure 2 and Figure 3 shown. The liquid film inner core includes an orifice plate 16. An inner sleeve 17 is connected below the orifice plate 16. The inner sleeve 17 is hollow, and a fiber bundle 18 composed of a large number of slender fiber filaments is arranged inside the inner sleeve 17. The fiber filaments are made of stainless steel, and the surface of the fiber filaments is treated hydrophilically, and the hydrophilic angle is about 3. A number of fiber bundle hanger cross pins are arranged on the orifice plate 16. Fiber bundle hangers 19 are arranged on the fiber bundle hanger cross pins. A number of fiber bundle hanging holes 20 are arranged on the orifice plate 16 corresponding to the fiber bundle hangers 19. The fiber bundle 18 is hung in the fiber bundle hanging holes 20 through the fiber bundle hangers 19. The internal structure of the caustic scrubbing organic sulfur reactor 4 is the same as that of the amine scrubbing organic sulfur reactor 1.

[0046] The ammonia removal coalescer 3 and the caustic removal coalescer 6 are coalescing separation structures of the same type. The structure of the ammonia removal coalescer 3 is as Figure 4 and Figure 5 shown. The ammonia removal coalescer 3 includes two layers of structures, namely a distribution orifice plate 33 and a mixed woven wire mesh. Among them, the distribution orifice plate 33 is as Figure 4 shown, and the material is stainless steel. A number of distribution holes are arranged on the distribution orifice plate 33. The distribution holes are arranged as full and evenly as possible on the distribution orifice plate 33. The flow rate of the material passing through the distribution holes is controlled in the range of 0.01 - 0.1 m / s. The structure of the mixed woven wire mesh is as Figure 5 shown, and it is woven by stainless steel wires 35 and polymer fibers 34. The diameter of the stainless steel wires is 0.1 - 0.2 mm, and the surface of the stainless steel wires is treated hydrophilically, and its hydrophilic angle is about 3; the polymer fibers are polyphenylene sulfide fibers or high molecular polyethylene materials, and the diameter of the polymer fibers is 0.2 - 0.4 mm. The specific weaving structure is carried out in the manner of the existing technology.

[0047] For the number of the amine-washing organic sulfur reactors 1 and the amine-washing separation tanks 2, it can be designed as one stage or multiple stages according to the liquid hydrocarbon sulfur content and the product desulfurization precision requirement. For example, multiple amine-washing organic sulfur reactors 1 and amine-washing separation tanks 2 are provided, each amine-washing organic sulfur reactor 1 is connected to an amine-washing separation tank 2, and each group of amine-washing organic sulfur reactors 1 and amine-washing separation tanks 2 are arranged in series. For the number of the caustic-washing organic sulfur reactors 4, it can be designed as one stage or multiple stages of caustic-washing organic sulfur reactors 4 according to the mercaptan content remaining in the liquid hydrocarbon after amine-washing and the product desulfurization precision requirement. For example, multiple caustic-washing organic sulfur reactors 4 are provided, and the multiple caustic-washing organic sulfur reactors 4 are arranged in series. The last caustic-washing organic sulfur reactor 4 is connected to the caustic-washing separation tank 5.

[0048] An oxidation zone and a stripping zone are arranged in the caustic liquor regeneration tower 7, and the oxidation zone and the stripping zone are separated by a full-welded partition plate; the oxidation zone and the stripping zone are distributed left and right and the upper parts of the oxidation zone and the stripping zone are connected, but the lower parts of the oxidation zone and the stripping zone are not connected; the rich caustic liquor pipe 26 is connected to the bottom of the oxidation zone, and the caustic liquor pipe 27 is connected to the bottom of the stripping zone.

[0049] An air distributor 9 and an oxidation packing zone 8 are distributed from bottom to top in the oxidation zone. The air distributor 9 is connected to an air inlet pipe 30. Oxidation packing is filled in the oxidation packing zone 8. The oxidation packing can be ceramic balls, Pall rings, Raschig rings, corrugated packing, wire mesh packing, etc., and corrugated packing is preferably used. An alkali liquor heater 13 and a catalyst injector 15 are sequentially arranged on the rich caustic liquor pipe 26. The catalyst injector 15 is used for injecting a mercaptan desulfurization catalyst into the rich caustic liquor pipe 26. The mercaptan desulfurization catalyst is cobalt phthalocyanine sulfonate or ammonium cobalt phthalocyanine sulfonate.

[0050] A nitrogen distributor 11 and a stripping packing zone 10 are distributed from bottom to top in the stripping zone. The nitrogen distributor 11 is connected to a nitrogen inlet pipe 31. Stripping packing is filled in the stripping packing zone 10. The stripping packing can be ceramic balls, Pall rings, Raschig rings, corrugated packing, wire mesh packing, etc., and corrugated packing is preferably used. An alkali liquor cooler 14 and an alkali liquor pump 12 are sequentially arranged on the caustic liquor pipe 27. An alkali liquor supplement pipe 28 is connected between the alkali liquor cooler 14 and the alkali liquor pump 12. The alkali liquor is also connected to a waste caustic liquor pipe 29 after passing through the alkali liquor pump 12. When the alkali liquor components in the pipe do not meet the use requirements, the alkali liquor can be discharged out of the system through the waste caustic liquor pipe.

[0051] The present invention also provides a method for precise desulfurization of liquid hydrocarbon caustic sludge with near-zero emission, which adopts the above-mentioned precise desulfurization device for liquid hydrocarbon caustic sludge with near-zero emission, and specifically includes:

[0052] S1. Feed the sulfur-containing liquid hydrocarbon into the amine-washing organic sulfur reactor 1 through the liquid hydrocarbon feed pipe 21, and at the same time feed the lean amine solution into the amine-washing organic sulfur reactor 1 through the lean amine solution pipe 24. The liquid hydrocarbon is subjected to amine-washing desulfurization treatment through the amine-washing organic sulfur reactor 1 and the amine-washing separation tank 2. The lean amine solution is composed of a compound of UDS desulfurizer and MDEA (methyldiethanolamine), in which the mass ratio of the UDS desulfurizer is 5%, the mass ratio of MDEA is 45%, and the remaining components are demineralized water or softened water. The UDS desulfurizer is an alkanolamine compound and a nitrogen-containing heterocyclic compound. The lean amine solution fed into the amine-washing organic sulfur reactor is 60 - 120% of the mass flow rate of the liquid hydrocarbon.

[0053] The sulfur-containing liquid hydrocarbon and the lean amine solution are in full contact in the amine-washing organic sulfur reactor 1. Hydrogen sulfide, carbonyl sulfide and most of the mercaptans in the liquid hydrocarbon are absorbed by the compound lean amine solution. The rich amine solution after absorbing sulfides and the liquid hydrocarbon are sedimentationally separated in the amine-washing separation tank 2, and then further thoroughly separated through the deamination coalescence separator 3. The rich amine solution is sent to the amine solution regeneration system by its own pressure to become the lean amine solution. After amine-washing, the hydrogen sulfide removal rate of the liquid hydrocarbon can reach more than 99.99%, the carbonyl sulfide removal rate can reach more than 99%, the mercaptan removal rate can reach more than 80%, and the amine solution entrainment amount in the liquid hydrocarbon does not exceed 200 ppm.

[0054] S2. Feed the liquid hydrocarbon after amine-washing desulfurization into the caustic-washing organic sulfur reactor 4, and at the same time feed the caustic solution into the caustic-washing organic sulfur reactor 4 for further desulfurization treatment through the caustic-washing organic sulfur reactor 4 and the caustic-washing separation tank 5. The liquid hydrocarbon after washing and desulfurization and the caustic solution are in full contact in the caustic-washing organic sulfur reactor 4. The remaining small amount of mercaptans in the liquid hydrocarbon react with sodium hydroxide in the caustic solution to form sodium mercaptide. The rich caustic solution dissolved with sodium mercaptide and the liquid hydrocarbon are sedimentationally separated in the caustic-washing separation tank 5, and then further thoroughly separated through the de-alkali coalescence separator 6. The rich caustic solution is sent to the caustic solution regeneration tower 7 by its own pressure, and the refined liquid hydrocarbon is collected through the refined liquid hydrocarbon pipe 23.

[0055] The mass flow ratio of the caustic solution fed into the caustic-washing organic sulfur reactor 4 to the liquid hydrocarbon is 10 - 50%. The concentration of sodium hydroxide in the caustic solution is not less than 5%, and the temperature of the caustic solution is controlled at 30 - 45°C.

[0056] After two-step desulfurization treatment of the liquid hydrocarbon, the total sulfur can be removed to 10 mg / m 3 Hereinafter, the alkaline water entrainment amount in the liquid hydrocarbon does not exceed 200 ppm.

[0057] S3. The rich caustic solution flowing out of the caustic-washing separation tank 5 is subjected to desulfurization treatment through the caustic solution regeneration tower 7 to control the contents of sodium mercaptide and disulfide in the caustic solution within the set range.

[0058] Before entering the caustic liquor regeneration tower 7, the rich caustic liquor is heated to 50 - 65 °C. Before entering the caustic liquor regeneration tower 7, a mercaptan removal catalyst is introduced into the rich caustic liquor so that the concentration of the mercaptan removal catalyst in the rich caustic liquor is controlled at 100 - 200 ppm. The operating pressure at the top of the caustic liquor regeneration tower is controlled between 0.1 - 0.3 MPa.

[0059] Air is introduced into the air distributor 9 through the air inlet pipe 30 and dispersed into fine bubbles in the air distributor 9, so that it can be evenly distributed in the caustic liquor when the caustic liquor passes through. The volume ratio of the introduced air to the caustic liquor is 10 - 30:1. The bubbles and the caustic liquor flow upward through the oxidation packing zone 8 and come into full contact. Under the action of the mercaptan removal catalyst, sodium mercaptide in the caustic liquor reacts with oxygen in the air to generate sodium hydroxide and disulfide. Sodium hydroxide dissolves in the caustic liquor, part of the disulfide is emulsified in the caustic liquor, and part of the disulfide is carried away with the oxidation tail gas through the tail gas pipe 32.

[0060] After oxidation, the caustic liquor overflows through the full-welded baffle into the stripping zone. Nitrogen for stripping is introduced into the nitrogen distributor 11 through the nitrogen inlet pipe 31 and dispersed into fine bubbles in the nitrogen distributor 11, so that it can be evenly distributed in the caustic liquor when the caustic liquor passes through. The volume ratio of the introduced nitrogen to the caustic liquor is 30 - 90:1. The bubbles pass upward through the stripping packing zone 10 and come into full contact with the caustic liquor. The disulfide in the caustic liquor dissolves in the nitrogen bubbles and is carried away with the tail gas through the tail gas pipe 32.

[0061] The caustic liquor after stripping is cooled to about 40 °C by the caustic liquor cooler 14 and pressurized by the caustic liquor pump 12 for the circulating mercaptan removal of the liquid hydrocarbon. The contents of sodium mercaptide and disulfide in the regenerated caustic liquor can be controlled below 100 ppm to ensure that the regenerated caustic liquor maintains a high mercaptan removal capacity in the long term.

[0062] In the first step of amine washing of the present invention, hydrogen sulfide, carbonyl sulfide, and most of the mercaptans have been removed. In the second step of caustic washing, only a small part of the mercaptans need to be removed. The amount of air required for the oxidation of the rich caustic liquor is very small, and the consumption of carbon dioxide in the air for the caustic liquor is correspondingly very small. Nitrogen stripping to remove disulfide does not consume the caustic liquor and increase the discharge of caustic sludge. Therefore, the present invention can achieve nearly zero discharge of liquid hydrocarbon desulfurization caustic sludge.

[0063] Example 1

[0064] This example adopts the liquid hydrocarbon caustic sludge nearly zero discharge fine desulfurization device and method provided by the present invention, aiming at the by-product light hydrocarbon recovered liquid hydrocarbon of an oil and gas field company. The hydrogen sulfide content in the liquid hydrocarbon is 10,000 - 15,000 mg / m 3 , the carbonyl sulfide content is 50 - 100 mg / m 3 , and the mercaptan content is 400 - 500 mg / m 3, desulfurization is carried out by using the near-zero-emission fine desulfurization device and method for liquid hydrocarbon alkali residue provided by the present invention. Among them, both the amine-washing organic sulfur reactor 1 and the alkali-washing organic sulfur reactor are set at the first level. After amine washing, the hydrogen sulfide content in the liquid hydrocarbon is less than 1 mg / m 3 , the carbonyl sulfide content is less than 1 mg / m 3 , and the total sulfur in the refined liquid hydrocarbon after alkali washing does not exceed 5 mg / m 3 .

[0065] Example 2

[0066] In this example, the near-zero-emission fine desulfurization device and method for liquid hydrocarbon alkali residue provided by the present invention are adopted. For the liquefied gas produced by the catalytic unit of a petrochemical company, the hydrogen sulfide content in the liquefied gas is 10,000 - 20,000 mg / m 3 , the carbonyl sulfide content is less than 5 mg / m 3 , the mercaptan content is 200 - 300 mg / m 3 , desulfurization is carried out by using the near-zero-emission fine desulfurization device and method for liquid hydrocarbon alkali residue provided by the present invention. Among them, both the amine-washing organic sulfur reactor and the alkali-washing organic sulfur reactor are set at the first level. After amine washing, the hydrogen sulfide content in the liquid hydrocarbon is less than 1 mg / m 3 , the carbonyl sulfide content is less than 1 mg / m 3 , and the total sulfur in the refined liquid hydrocarbon after alkali washing does not exceed 3 mg / m 3 .

[0067] Example 3

[0068] In this example, the near-zero-emission fine desulfurization device and method for liquid hydrocarbon alkali residue provided by the present invention are adopted. For the liquid hydrocarbon recovered from the by-product light hydrocarbon of an oil and gas field company, the scale of the liquefied gas is 130,000 tons / year, and the hydrogen sulfide content in the liquid hydrocarbon is 15,000 - 20,000 mg / m 3 , the carbonyl sulfide content is 20 - 50 mg / m 3 , the mercaptan content is 500 - 800 mg / m 3 , desulfurization is carried out by using the near-zero-emission fine desulfurization device and method for liquid hydrocarbon alkali residue provided by the present invention. Among them, both the amine-washing organic sulfur reactor and the alkali-washing organic sulfur reactor are set at the first level. After amine washing, the hydrogen sulfide content in the liquid hydrocarbon is less than 1 mg / m 3 , the carbonyl sulfide content is less than 1 mg / m 3 , and the total sulfur in the refined liquid hydrocarbon after alkali washing does not exceed 10 mg / m 3 , the entrainment amount of alkaline water does not exceed 200 ppm, and 10 tons of alkali residue are discharged during the one-year operation of the device.

[0069] The above specific embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the scope of the technical solutions of the present invention, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. A fine desulfurization device for near-zero emission of liquid hydrocarbon caustic sludge, characterized in that, It includes an amine-washing organic sulfur reactor and an alkali-washing organic sulfur reactor. One side of the amine-washing organic sulfur reactor is connected to a liquid hydrocarbon raw material pipe and a lean amine liquid pipe; the amine-washing organic sulfur reactor is connected to an amine-washing separation tank, the amine-washing separation tank is connected to the alkali-washing organic sulfur reactor, and one side of the alkali-washing organic sulfur reactor is also connected to an alkali liquid pipe, and the alkali-washing organic sulfur reactor is connected to an alkali-washing separation tank; the alkali-washing separation tank is connected to a refined liquid hydrocarbon pipe.

2. The refined desulfurization device for near-zero emission of liquid hydrocarbon alkali residue according to claim 1, characterized in that, A deammoniation coalescer separator is also arranged in the amine-washing separation tank, and the deammoniation coalescer separator is arranged at the rear side of the amine-washing separation tank; One side of the rear side of the amine-washing separation tank is connected to the alkali-washing organic sulfur reactor through a liquid hydrocarbon pipe after amine washing, and the bottom of the rear side of the amine-washing separation tank is connected to a rich amine liquid pipe.

3. The fine desulfurization device for near-zero emission of liquid hydrocarbon caustic sludge according to claim 1, characterized in that, The alkali-washing organic sulfur reactor is installed on the alkali-washing separation tank through a flange. A de-alkali coalescer separator is also arranged in the alkali-washing separation tank, and the de-alkali coalescer separator is arranged at the rear side of the alkali-washing separation tank; The rear side of the alkali-washing separation tank is connected to a refined liquid hydrocarbon pipe, and the rear side of the alkali-washing separation tank is also connected to a rich alkali liquid pipe.

4. The fine desulfurization device for near-zero emission of liquid hydrocarbon caustic sludge according to claim 3, characterized in that, The liquid hydrocarbon alkali residue near-zero emission fine desulfurization device also includes an alkali liquid regeneration tower. The alkali liquid regeneration tower is connected to the rich alkali liquid pipe, and the alkali liquid flowing out of the alkali liquid regeneration tower flows into the alkali-washing organic sulfur reactor through the alkali liquid pipe.

5. The liquid hydrocarbon caustic sludge near-zero emission fine desulfurization device according to claim 4, wherein An oxidation zone and a stripping zone are arranged in the alkali liquid regeneration tower. The oxidation zone and the stripping zone are distributed left and right and the upper parts of the oxidation zone and the stripping zone are connected; the rich alkali liquid pipe is connected to the bottom of the oxidation zone, and the alkali liquid pipe is connected to the bottom of the stripping zone.

6. The refined desulfurization device for near-zero emission of liquid hydrocarbon caustic sludge according to claim 5, wherein An air distributor and an oxidation packing zone are distributed from bottom to top in the oxidation zone, and the air distributor is connected to an air inlet pipe.

7. The refined desulfurization device for near-zero emission of liquid hydrocarbon alkali residue according to claim 6, characterized in that, An alkali liquid heater and a catalyst injector are sequentially arranged on the rich alkali liquid pipe, and the catalyst injector is used for injecting a mercaptan desulfurization catalyst into the rich alkali liquid pipe.

8. The refined desulfurization device for near-zero emission of liquid hydrocarbon alkali residue according to claim 5, wherein A nitrogen distributor and a stripping packing zone are distributed from bottom to top in the stripping zone, and the nitrogen distributor is connected to a nitrogen inlet pipe.

9. The fine desulfurization device for near-zero emission of liquid hydrocarbon alkali residue according to claim 8, characterized in that, An alkali liquid cooler and an alkali liquid pump are sequentially arranged on the alkali liquid pipe, and an alkali liquid supplement pipe is connected between the alkali liquid cooler and the alkali liquid pump.

10. A method for near-zero emission fine desulfurization of liquid hydrocarbon alkali residue, using the liquid hydrocarbon alkali residue near-zero emission fine desulfurization device described in any one of claims 1-9, characterized in that, Specifically, it includes: S1. Pass the sulfur-containing liquid hydrocarbon into the amine-washing organic sulfur reactor through the liquid hydrocarbon raw material pipe, and at the same time pass the lean amine liquid into the amine-washing organic sulfur reactor through the lean amine liquid pipe. The liquid hydrocarbon undergoes amine-washing desulfurization treatment through the amine-washing organic sulfur reactor and the amine-washing separation tank; S2. The liquid hydrocarbon after amine-washing desulfurization is passed into the alkali-washing organic sulfur reactor, and at the same time the alkali liquid is passed into the alkali-washing organic sulfur reactor, and further desulfurization treatment is carried out through the alkali-washing organic sulfur reactor and the alkali-washing separation tank.

11. The method for near-zero emission fine desulfurization of liquid hydrocarbon caustic sludge according to claim 10, characterized in that, After the desulfurization treatment in step S2, the rich alkali liquid flowing out of the alkali-washing separation tank undergoes desulfurization treatment through the alkali liquid regeneration tower to control the contents of sodium mercaptide and disulfide in the alkali liquid within a set range.

12. The method for near-zero emission fine desulfurization of liquid hydrocarbon alkali residue according to claim 11, characterized in that, Before entering the alkali liquid regeneration tower, the rich alkali liquid is heated to 50 - 65 °C; Before entering the alkali liquid regeneration tower, a mercaptan desulfurization catalyst is introduced into the rich alkali liquid so that the concentration of the mercaptan desulfurization catalyst in the rich alkali liquid is controlled at 100 - 200 ppm.

13. The method for near-zero emission fine desulfurization of liquid hydrocarbon caustic sludge according to claim 10, characterized in that, The lean amine solution is composed of a UDS desulfurizer and MDEA in a compound form, where the mass ratio of the UDS desulfurizer is 5%, the mass ratio of MDEA is 45%, and the remaining components are demineralized water or softened water.

14. The method for near-zero emission fine desulfurization of liquid hydrocarbon caustic sludge according to claim 13, characterized in that, The lean amine solution fed into the amine-washing organic sulfur reactor is 60 - 120% of the mass flow rate of the liquid hydrocarbon.

15. The method for near-zero emission fine desulfurization of liquid hydrocarbon alkali residue according to claim 10, wherein, In step S2, the mass flow rate ratio of the caustic solution fed into the caustic-washing organic sulfur reactor to the liquid hydrocarbon is 10 - 50%.

16. The near-zero emission fine desulfurization method for liquid hydrocarbon alkali residue according to claim 10, characterized in that, In step S2, the concentration of sodium hydroxide in the caustic solution is not less than 5%, and the temperature of the caustic solution is controlled at 30 - 45°C.

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