Complex iron desulfurization device and process for hydrogenated dry gas

Abstract

The invention relates to the technical field of hydrogen sulfide removal, in particular to a complex iron desulfurization device and process for hydrogenated dry gas, the hydrogenated dry gas is communicated with a dry gas condenser, and the dry gas condenser is communicated with a dry gas buffer tank; the dry gas buffer tank is connected with the high-performance oil absorption resin tank; the high-performance oil absorption resin tank is communicated with the desulfurization tower; the desulfurization tower is communicated with the energy recovery equipment; the energy recovery equipment liquid is communicated with the flash tank; the flash tank is communicated with the regeneration tower; the regeneration tower is communicated with the plate-and-frame filter; and a solid sulfur outlet of the plate-and-frame filter is communicated with the sulfur melting kettle. According to the present invention, the C5 + component in the hydrogenation dry gas is pretreated by using the low-temperature condensation and high-performance oil absorption resin selective adsorption process, such that the interference of the C5 + component on the subsequent desulfurization device is eliminated, the operation of the dry gas complex iron desulfurization device is stabilized, the organic matter of the sulfur product is reduced, and the grade of the sulfur product is improved; and meanwhile, flash steam energy is recycled to serve as a heat source for desorption heat regeneration of the oil absorption resin, so that the power consumption is reduced, and the operation cost of the whole device is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen sulfide removal, and in particular to a complex iron desulfurization device and process for hydrogenated dry gas. Background Art

[0002] Refinery hydrogenation dry gas is mainly acidic gas containing high concentration of H2S produced by the front-end hydrogenation unit. The gas is generated by the hydrogenation reaction of organic sulfur components (such as sulfides, mercaptans and thiophenes) in the crude oil. The generated hydrogen sulfide gas is usually discharged in the form of low-fraction gas, high-fraction gas and two types of dry gas. Since the hydrocarbon and hydrogen components in the dry gas are relatively high, it needs to be desulfurized and recovered. Usually, refineries use MDEA adsorption and desulfurization + Claus sulfur recovery unit to achieve sulfur recovery. This process has a much higher investment area and energy consumption for enterprises with low sulfur load (<20 tons / day sulfur) than the complex iron wet oxidation desulfurization process.

[0003] The complex iron desulfurization process can directly oxidize the H2S in the hydrogenated dry gas to generate sulfur in one step. However, the direct desulfurization of hydrogenated dry gas with complex iron will also encounter unstable operation problems such as severe liquid entrainment in the flushing tower and purified gas during gas absorption similar to MDEA desulfurization. For this reason, we propose a complex iron desulfurization device and process for hydrogenated dry gas. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a complex iron desulfurization device and process for hydrogenated dry gas, which removes the C5+ component to the greatest extent by adopting a combination process of low-temperature condensation pre-separation + high-performance oil absorption resin, thereby ensuring the smooth operation of the subsequent complex iron desulfurization device, and solving the unstable operation problem of direct desulfurization of complex iron with hydrogenated dry gas in the existing complex iron desulfurization process, such as severe liquid contamination in the flushing tower and purified gas during gas absorption, which is similar to MDEA desulfurization.

[0005] The present invention provides the following technical solution: a complex iron desulfurization device for hydrogenated dry gas, comprising a dry gas condenser, a dry gas buffer tank, a C5+ heavy hydrocarbon buffer tank, a high-performance oil-absorbing resin tank, a desulfurization tower, a flash tank, and an alkali solution absorption tank;

[0006] The gas inlet of the dry gas condenser receives the hydrogenated dry gas from the hydrogenation device through the first pipeline, and the gas outlet of the dry gas condenser is connected to the dry gas buffer tank through the second pipeline; the gas outlet of the dry gas buffer tank is connected to the first high-performance oil-absorbing resin tank through the third pipeline, and the liquid outlet of the dry gas buffer tank is connected to the C5+ heavy hydrocarbon buffer tank through the fourth pipeline. The C5+ heavy hydrocarbon buffer tank is used to flash out a small amount of hydrogen sulfide dissolved in the C5+ liquid, and the flashed sulfur-containing non-condensable gas is sent to the alkali solution absorption tank through the twenty-fifth pipeline;

[0007] The gas outlet of the first high-performance oil-absorbing resin tank is connected to the second high-performance oil-absorbing resin tank through a fifth pipeline; the gas outlet of the second high-performance oil-absorbing resin tank is connected to the desulfurization tower through a sixth pipeline;

[0008] The gas outlet of the flash tank is connected to the fuel gas system outside the boundary area through an eleventh pipeline.

[0009] Preferably, it also includes energy recovery equipment and a regeneration tower, the liquid inlet of the desulfurization tower is connected with the regeneration tower through the seventh pipeline, and the liquid outlet of the desulfurization tower is connected with the energy recovery equipment through the eighth pipeline; the liquid outlet of the energy recovery equipment is connected with the flash tank through the ninth pipeline; the liquid outlet of the flash tank is connected with the regeneration tower through the tenth pipeline.

[0010] Preferably, the liquid outlet of the regeneration tower is connected to the plate-frame filter through a twelfth pipeline, and the gas outlet of the regeneration tower is connected to the VOCs purification equipment outside the boundary area through a thirteenth pipeline; the solid sulfur outlet of the plate-frame filter is connected to the sulfur melting kettle through a fourteenth pipeline;

[0011] The liquid sulfur outlet of the sulfur melting kettle is connected to the sulfur forming machine outside the boundary area through the twenty-ninth pipeline, and the gas outlet of the sulfur melting kettle is connected to the VOCs purification equipment outside the boundary area through the thirtieth pipeline;

[0012] The lean liquid outlet of the regeneration tower is connected to the desulfurization tower via the lean liquid pump inlet pipe, the lean liquid pump, the thirty-second pipe, the solution heat exchanger and the seventh pipe in sequence, and the slurry outlet of the regeneration tower is connected to the plate and frame filter via the sulfur slurry pump inlet pipe, the sulfur slurry pump and the twelfth pipe in sequence.

[0013] Preferably, the liquid inlet of the dry gas condenser is connected to the low-temperature cold water supply outside the boundary area through a thirty-fourth pipeline, and the liquid outlet of the dry gas condenser is connected to the low-temperature cold water return outside the boundary area through a thirty-fifth pipeline.

[0014] Preferably, the energy recovery equipment is used to recycle the residual pressure of the rich liquid flash evaporation and convert it into electric heating energy for the nitrogen heater. The nitrogen inlet of the nitrogen heater is connected with the nitrogen preheater through the fifteenth pipeline, and the outlet of the nitrogen heater is connected with the high-performance oil-absorbing resin tank through the sixteenth pipeline, the seventeenth pipeline and the eighteenth pipeline; the nitrogen inlet of the nitrogen preheater is connected with the nitrogen pipeline outside the boundary area through the nineteenth pipeline.

[0015] Preferably, the liquid level control valve of the desulfurization tower is arranged on the ninth pipeline; the pressure control valve 1 of the flash tank is arranged on the eleventh pipeline; and the pressure control valve 2 of the C5+ heavy hydrocarbon buffer tank is arranged on the twenty-fifth pipeline.

[0016] Preferably, the filtrate outlet of the plate and frame filter is connected to the regeneration tower through the filtrate pump inlet pipe, the filtrate pump and the thirty-first pipe.

[0017] Preferably, the desulfurization tower contains a dry gas distributor, and the dry gas distributor inside the desulfurization tower is connected through a sixth pipeline;

[0018] The regeneration tower contains an air distributor inside, and the air distributor inside the regeneration tower is connected to the air fan through an air inlet pipeline.

[0019] A complex iron desulfurization process for hydrogenated dry gas comprises the following steps: pretreatment of hydrogenated dry gas:

[0020] The hydrogenated dry gas from the hydrogenation unit is transported to the inlet of the dry gas condenser through the first pipeline, and most of the C5+ components in the dry gas are cooled down by low-temperature cold water, and then transported to the dry gas buffer tank through the second pipeline for gas-liquid separation. The dry gas separated at the top enters two high-performance oil-absorbing resin tanks running in series through the third pipeline to achieve deep removal of the C5+ components to less than 0.01V%. The pretreated hydrogenated dry gas enters the desulfurization tower of the complex iron desulfurization absorption part; the C5+ liquid separated at the bottom of the dry gas buffer tank flows into the C5+ heavy hydrocarbon buffer tank at normal pressure through the fourth pipeline to flash out a small amount of hydrogen sulfide dissolved in the C5+ liquid, and the flashed sulfur-containing non-condensable gas is sent to an alkali absorption tank at a certain alkali height through the twenty-fifth pipeline, and the C5+ product separated at the bottom of the C5+ heavy hydrocarbon buffer tank is sent out of the boundary area for recovery through the twenty-sixth pipeline.

[0021] Preferably, after the hydrogenation dry gas is pretreated, hydrogen sulfide absorption, rich liquid flash evaporation, solution oxidation regeneration, sulfur slurry filtration and sulfur refining are required, and the specific steps are as follows:

[0022] Hydrogen sulfide absorption:

[0023] The gas absorbed by hydrogen sulfide includes: dry gas containing hydrogen sulfide after pretreatment of hydrogenated dry gas; non-condensable gas containing hydrogen sulfide flashed out from C5+ heavy hydrocarbon buffer tank; regenerated gas containing hydrogen sulfide produced by desorption of high-performance oil absorption resin tank;

[0024] The hydrogenated dry gas enters the desulfurization tower with a certain liquid level for bubbling absorption. The regenerated lean liquid from the regeneration tower is transported to the desulfurization tower through the 32nd pipeline by the lean liquid pump. The H2S in the hydrogenated dry gas enters the liquid phase and is oxidized by the trivalent complex iron ions in the desulfurizer lean liquid to generate sulfur. The desulfurization liquid containing sulfur, also called rich liquid, is sent to the rich liquid flash evaporation part. The purified dry gas after desulfurization is sent to the purified gas recovery device outside the boundary area through the 33rd pipeline.

[0025] When the resin in the high-performance oil-absorbing resin tank is adsorbed to a certain degree and reaches a saturated state, it needs to be regenerated by thermal nitrogen; the nitrogen outside the boundary area first passes through the nitrogen preheater and the 350-400°C regeneration gas generated by the desorption of the resin tank to undergo heat exchange to 150-200°C, and then passes through the fifteenth pipeline to the nitrogen heater to be heated to 400°C to become hot nitrogen, and the hot nitrogen enters one of the high-performance oil-absorbing resin tanks to be regenerated for heating, regeneration and desorption, and the thermally desorbed C5+ component is condensed with the regeneration gas through the nitrogen preheater and the regeneration gas condenser and then enters the C5+ heavy hydrocarbon buffer tank to achieve gas-liquid separation; the sulfur-containing regeneration gas generated by separation is combined with the non-condensable gas from the C5+ heavy hydrocarbon buffer tank for absorption and desulfurization;

[0026] The separated sulfur-containing regeneration gas and the hydrogen sulfide in the non-condensable gas from the C5+ heavy hydrocarbon buffer tank are first neutralized and absorbed by alkali solution to generate divalent sulfur, and then sent to the regeneration tower through the 27th pipeline using the height difference of the alkali solution absorption tank, wherein the divalent sulfur ions react with the trivalent complex iron ions in the regeneration tower to generate sulfur through oxidation, and also play the purpose of replenishing alkali consumption; the qualified non-condensable gas purified by the alkali solution absorption tank is sent to the fuel gas system outside the boundary area through the 28th pipeline;

[0027] Rich liquid flash evaporation:

[0028] The rich liquid with a certain pressure is discharged from the liquid outlet at the bottom of the desulfurization tower and enters the energy recovery device through the eighth pipeline. The residual pressure of the rich liquid flash evaporation is recovered and reused, converted into electric heating energy of the nitrogen heater, and hot nitrogen is provided for the high-performance oil-absorbing resin tank to achieve regeneration; the liquid after energy recovery of the rich liquid enters the subsequent regeneration tower through the ninth pipeline to achieve oxidation regeneration of the desulfurizer;

[0029] Solution oxidation regeneration:

[0030] The sulfur-containing rich liquid is in multi-stage contact with the regeneration air bubbled from the air blower in the regeneration tower. The complex ferrous iron is oxidized to complex iron by oxygen, and the sulfur particles grow at the same time. The regeneration waste air enters the VOCs purification facility outside the boundary area from the gas outlet at the upper end of the regeneration tower through the thirteenth pipeline;

[0031] Sulfur slurry filtration:

[0032] Under the action of natural gravity, the sulfur in the solid-liquid mixture after regeneration settles to the bottom of the regeneration tower cone and concentrates to become sulfur slurry. The sulfur slurry pump is pumped out from the outlet of the regeneration tower cone bottom and sent to the plate and frame filter through the twelfth pipeline to realize solid sulfur and separate it from the desulfurizer. The separated filtrate is sent back to the regeneration tower through the filtrate pump, and the filtered and separated solid sulfur paste is sent to the sulfur refining part;

[0033] Sulfur refining:

[0034] The filtered sulfur paste enters the sulfur melting kettle through the fourteenth pipeline. The sulfur melting kettle adopts low-pressure steam jacket heating to separate the sulfur and liquid in the sulfur paste. The liquid sulfur produced by melting at the bottom of the sulfur melting kettle is sent out of the boundary to be formed. The exhaust gas generated by the pressure relief of the sulfur melting kettle is sent to the VOCs purification equipment outside the boundary area through the thirtieth pipeline.

[0035] The present invention provides a complex iron desulfurization device and process for hydrogenated dry gas. On the basis of traditional complex iron desulfurization, low-temperature condensation pre-separation and high-performance oil absorption resin pretreatment of C5+ in dry gas are added, which can reduce the selectivity of C5+ components in dry gas entering the desulfurization device to less than 0.01V%, greatly reduce the absorption gas tower flushing phenomenon and purified gas liquid carrying phenomenon caused by easy foaming of C5+ to desulfurization liquid, and stabilize the operation of the device. It solves the unstable operation problem of tower flushing and severe liquid carrying of purified gas during gas absorption similar to MDEA desulfurization in the existing complex iron desulfurization process of hydrogenated dry gas complex iron direct desulfurization. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the structure of the present invention.

[0037] In the figure: 1, dry gas condenser; 101, first pipeline; 102, second pipeline; 103, third pipeline; 104, fourth pipeline; 105, fifth pipeline; 106, sixth pipeline; 107, seventh pipeline; 108, eighth pipeline; 109, ninth pipeline; 110, tenth pipeline; 111, eleventh pipeline; 112, twelfth pipeline; 113, thirteenth pipeline; 114, fourteenth pipeline; 115, fifteenth pipeline; 116, sixteenth pipeline; 117, seventeenth pipeline; 118, eighteenth pipeline; 119, nineteenth pipeline; 120, twentieth pipeline; 121, twenty-first pipeline; 122, twenty-second pipeline; 123, twenty-third pipeline; 124, twenty-fourth pipeline; 125, twenty-fifth pipeline; 126, twenty-sixth pipeline; 127, twenty-seventh pipeline; 128, twenty-eighth pipeline; 129, twenty-ninth pipeline; 130, thirtieth pipeline; 1 31. The 31st pipeline; 132. The 32nd pipeline; 133. The 33rd pipeline; 134. The 34th pipeline; 135. The 35th pipeline; 2. Dry gas buffer tank; 3. C5+ heavy hydrocarbon buffer tank; 4. High-performance oil absorption resin tank; 401. The first high-performance oil absorption resin tank; 402. The second high-performance oil absorption resin tank; 403. The third high-performance oil absorption resin tank; 5. Desulfurization tower; 6. Flash tank; 7. Energy recovery equipment; 8. Regeneration tower; 9. Plate and frame filter; 10. Molten sulfur kettle; 11. Alkali solution absorption tank; 12. Reagent tank; 13. Liquid level control valve; 14. Pressure control valve one; 15. Pressure control valve two; 16. High-performance oil-absorbing resin; 17. Dry gas distributor; 18. Air distributor; 19. Nitrogen heater; 20. Nitrogen preheater; 21. Regeneration gas condenser; 22. Lean liquid pump; 23. Solution heat exchanger; 24. Sulfur slurry pump; 25. Filtrate pump; 26. Air fan. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, the present invention provides a technical solution: a complex iron desulfurization device for hydrogenated dry gas, including a dry gas condenser 1, a dry gas buffer tank 2, a C5+ heavy hydrocarbon buffer tank 3, a high-performance oil absorption resin tank 4, a desulfurization tower 5, a flash tank 6, an energy recovery device 7, a regeneration tower 8, a plate and frame filter 9, a molten sulfur kettle 10, an alkali solution absorption tank 11 and a reagent tank 12.

[0040] The gas inlet of the dry gas condenser 1 receives the hydrogenated dry gas from the hydrogenation device through the first pipeline 101, and the gas outlet of the dry gas condenser 1 is connected to the dry gas buffer tank 2 through the second pipeline 102; the gas outlet of the dry gas buffer tank 2 is connected to the first high-performance oil-absorbing resin tank 401 through the third pipeline 103, and the liquid outlet of the dry gas buffer tank 2 is connected to the C5+ heavy hydrocarbon buffer tank 3 through the fourth pipeline 104; the gas outlet of the first high-performance oil-absorbing resin tank 401 is connected to the second high-performance oil-absorbing resin tank 402 through the fifth pipeline 105; the gas outlet of the second high-performance oil-absorbing resin tank 402 is connected to the desulfurization tower 5 through the sixth pipeline 106; the liquid inlet of the desulfurization tower 5 is connected to the first high-performance oil-absorbing resin tank 401 through the sixth pipeline 106. The seventh pipeline 107 is connected to the regeneration tower 8, and the liquid outlet of the desulfurization tower 5 is connected to the energy recovery device 7 through the eighth pipeline 108; the liquid outlet of the energy recovery device 7 is connected to the flash tank 6 through the ninth pipeline 109; the liquid outlet of the flash tank 6 is connected to the regeneration tower 8 through the tenth pipeline 110, and the gas outlet of the flash tank 6 is connected to the fuel gas system outside the boundary area through the eleventh pipeline 111; the liquid outlet of the regeneration tower 8 is connected to the plate and frame filter 9 through the twelfth pipeline 112, and the gas outlet of the regeneration tower 8 is connected to the VOCs purification equipment outside the boundary area through the thirteenth pipeline 113; the solid sulfur outlet of the plate and frame filter 9 is connected to the molten sulfur kettle 10 through the fourteenth pipeline 114.

[0041] The dry gas condenser 1 condenses most of the C5+ in the hydrogenated dry gas through low-temperature cold water, ensuring the low load of the subsequent oil-absorbing resin deep adsorption process of the C5+ component, and can adsorb the remaining C5+ components with sufficient capacity. The liquid inlet of the dry gas condenser 1 is connected to the low-temperature cold water supply outside the boundary area through the thirty-fourth pipeline 134, and the liquid outlet of the dry gas condenser 1 is connected to the low-temperature cold water return outside the boundary area through the thirty-fifth pipeline 135.

[0042] The high-performance oil-absorbing resin tank 4 utilizes the hydrophobicity of the high-performance oil-absorbing resin to absorb oil products. The oil molecules penetrate into the resin and are absorbed into the resin grid cavity. The resin is specifically designed for the selective adsorption of C5+ macromolecular hydrocarbons. The high-performance oil-absorbing resin 16 is generally provided with three units: the first high-performance oil-absorbing resin tank 401, the first high-performance oil-absorbing resin tank 402, and the first high-performance oil-absorbing resin tank 403. Two of the tanks are operated in series, and the other tank is regenerated for standby. The three high-performance oil-absorbing resin tanks 4 are regenerated by hot nitrogen regeneration to desorb the saturated C5+ components by heating.

[0043] In the existing complex iron desulfurization process, the direct desulfurization of hydrogenated dry gas complex iron will also encounter unstable operation problems such as gas absorption tower flushing and severe liquid carrying in purified gas, similar to MDEA desulfurization. The main reason for the unstable operation is that the upstream devices of the hydrogenated dry gas, such as the desulfurization hydrogen stripping tower, have fluctuations and unstable operation, which may cause the hydrogenated dry gas to carry a large amount of oil (mainly C5+ including C5). Once the C5+ component in the dry gas enters the desulfurization system and accumulates to a certain extent, it will cause the desulfurizer to foam and the generated sulfur particles to be difficult to grow together. The present invention adds low-temperature condensation pre-separation + high-performance oil absorption resin 16 pretreatment facilities in the dry gas C5+ on the basis of traditional complex iron desulfurization, which can reduce the selectivity of the dry gas C5+ component entering the desulfurization device to <0.01V%, greatly reducing the absorption gas tower flushing phenomenon and purified gas liquid carrying phenomenon caused by the easy foaming of C5+ to the desulfurization liquid, and stabilizing the operation of the device.

[0044] The energy recovery device 7 is a highly efficient hydraulic turbine device, which can recycle the residual pressure of the rich liquid flash evaporation and convert it into electric heating energy for the nitrogen heater 19. The nitrogen inlet of the nitrogen heater 19 is connected to the nitrogen preheater 20 through the fifteenth pipeline 115, and the outlet of the nitrogen heater 19 is connected to the first high-performance oil-absorbing resin tank 401, the second high-performance oil-absorbing resin tank 402, and the third high-performance oil-absorbing resin tank 403 through the sixteenth, seventeenth and eighteenth pipelines; the nitrogen inlet of the nitrogen preheater 20 is connected to the nitrogen pipeline outside the boundary area through the nineteenth pipeline 119.

[0045] Based on the complex iron desulfurization device and method, the present invention recovers the energy of the residual pressure of the rich liquid flash evaporation as the heating source of the hot nitrogen regeneration gas, which has the advantages of high energy utilization, low energy consumption and low operating cost. For example, a hydrogenation dry gas desulfurization device with a daily output of 2 tons of sulfur (pure) and an operating pressure of 0.5-0.8 MPa can recover 80%-85% of the power consumption of the lean liquid pump 22 by using the energy recovery device 7 of the present invention. The flow rate of the lean liquid pump 22 before recovery is 250m 3 / h, head 60-70m, motor shaft power is about 82-95kwh, 66-81kwh can be recovered by using energy recovery device 7, and 8000h of operation per year, 0.6 yuan / kWh, the energy recovery scheme of the present invention can save more than 310,000 to 390,000 yuan.

[0046] The regeneration gas outlets of the first high-performance oil-absorbing resin tank 401, the second high-performance oil-absorbing resin tank 402, and the third high-performance oil-absorbing resin tank 403 are connected to the nitrogen preheater 20 through the twentieth pipeline 120, the twenty-first pipeline 121, and the twenty-second pipeline 122; the regeneration gas outlet of the nitrogen preheater 20 is connected to the regeneration gas condenser 21 through the twenty-third pipeline 123; the regeneration gas condenser 21 is connected to the C5+ heavy hydrocarbon buffer tank 3 through the twenty-fourth pipeline 124; the gas outlet of the C5+ heavy hydrocarbon buffer tank 3 is connected to the alkali liquid absorption tank 11 through the twenty-fifth pipeline 125, and the liquid outlet of the C5+ heavy hydrocarbon buffer tank 3 is connected to the C5+ recovery facility outside the boundary area through the twenty-sixth pipeline 126; the liquid outlet of the alkali liquid absorption tank 11 is connected to the regeneration tower 8 through the twenty-seventh pipeline 127, and the gas outlet of the alkali liquid absorption tank 11 is connected to the fuel gas system outside the boundary area through the twenty-eighth pipeline 128.

[0047] The sulfur melting kettle 10 uses low-pressure steam to purify sulfur. The liquid sulfur outlet of the sulfur melting kettle 10 is connected to the sulfur forming machine outside the boundary area through the 29th pipeline 129, and the gas outlet of the sulfur melting kettle 10 is connected to the VOCs purification equipment outside the boundary area through the 30th pipeline 130. The present invention greatly reduces the VOCs in the regenerated waste air. S Medium and heavy hydrocarbon components C5+, reducing VOC S Processing costs of processing devices.

[0048] It also includes a plate and frame filter 9, and the filtrate outlet of the plate and frame filter 9 is connected to the regeneration tower 8 through the filtrate pump inlet pipeline, the filtrate pump 25 and the thirty-first pipeline 131.

[0049] The lean liquid outlet of the regeneration tower 8 is connected to the desulfurization tower 5 via the lean liquid pump inlet pipe, the lean liquid pump 22, the thirty-second pipe 132, the solution heat exchanger 23 and the seventh pipe 107 in sequence, and the slurry outlet of the regeneration tower 8 is connected to the plate and frame filter 9 via the sulfur slurry pump inlet pipe, the sulfur slurry pump 24 and the twelfth pipe 112 in sequence.

[0050] The purified gas outlet of the desulfurization tower 5 is connected to the purified gas recovery device outside the boundary area through the 33rd pipeline 133. The liquid level control valve 13 of the desulfurization tower 5 is arranged on the 9th pipeline 109. The pressure control valve 14 of the flash tank 6 is arranged on the 11th pipeline 111. The pressure control valve 2 15 of the C5+ heavy hydrocarbon buffer tank 3 is arranged on the 25th pipeline 125.

[0051] The desulfurization tower 5 contains a dry gas distributor 17, which is connected via a sixth pipeline 106. The regeneration tower 8 contains an air distributor 18, which is connected to an air blower 26 via an air inlet pipeline.

[0052] The present invention combines the two processes of alkali neutralization chemical absorption of H2S and complex iron sulfur recovery, and solves the atmospheric pressure flash gas desulfurization in a simple and low-cost way through delayed desulfurization. After the alkali solution neutralizes and absorbs the H2S in the flash gas, the S is temporarily locked in the solution into a negative divalent ion state, and then enters the complex iron desulfurization system to react with divalent sulfur ions to generate sulfur element. At the same time, the complex ferrous iron generates OH- through oxygen regeneration reaction. The alkali solution is not consumed, and it plays a dual role of absorption and alkali replenishment.

[0053] Reaction in the alkali solution absorption tank:

[0054]

[0055] Reaction in regeneration tower: HS - (L)+2Fe 3+ (R)→2Fe 2+ (R)+H + (L)+S↓

[0056] 1 / 2O2(L)+H2O(L)+2Fe 2+ (R)→2OH - (L)+2Fe 3+ (R)

[0057] Note: (g)——gas phase, (L)——liquid phase, (R)——complexing agent

[0058] Compared with the conventional complex iron sulfur melting device, the present invention can reduce the organic matter content in the molten sulfur from ≤0.8wt% to ≤0.3wt%, and increase the sulfur content from ≥99.0wt% to ≥99.5wt%, reaching the Class B standard in the national industrial solid sulfur standard GB / T 2449.1-2021.

[0059] A complex iron desulfurization process for hydrogenated dry gas comprises the following steps:

[0060] S1. Hydrogenation dry gas pretreatment

[0061] The hydrogenated dry gas from the hydrogenation unit is transported to the inlet of the dry gas condenser 1 through the first pipeline 101, and most of the C5+ components in the dry gas are cooled down by low-temperature cold water, and then sent to the dry gas buffer tank 2 through the second pipeline 102 for gas-liquid separation. The dry gas separated at the top enters two high-performance oil-absorbing resin tanks 4 running in series through the third pipeline 103 to achieve deep removal of the C5+ components to less than 0.01V%. The pretreated hydrogenated dry gas enters the complex iron desulfurization absorption partial desulfurization tower.

[0062] The C5+ liquid separated at the bottom of the dry gas buffer tank 2 flows into the C5+ heavy hydrocarbon buffer tank 3 at normal pressure through the fourth pipeline 104 to flash out a small amount of hydrogen sulfide dissolved in the C5+ liquid, and the flashed sulfur-containing non-condensable gas is sent to the alkali solution absorption tank 11 with a certain alkali solution height through the twenty-fifth pipeline 125. The C5+ product separated at the bottom of the C5+ heavy hydrocarbon buffer tank 3 is sent out of the boundary area for recovery through the twenty-sixth pipeline 126.

[0063] S2, Hydrogen sulfide absorption

[0064] The gas absorbed by hydrogen sulfide includes: 1. dry gas containing hydrogen sulfide after pretreatment of hydrogenated dry gas; 2. non-condensable gas containing hydrogen sulfide flashed out from C5+ heavy hydrocarbon buffer tank 3; 3. regenerated gas containing hydrogen sulfide produced by desorption of high-performance oil absorption resin tank 4.

[0065] S2.1. The hydrogenated dry gas enters the desulfurization tower 5 at a certain liquid level for bubbling absorption. The regenerated lean liquid from the regeneration tower 8 is transported to the desulfurization tower 5 via the lean liquid pump 22 through the thirty-second pipeline 132. The H2S in the hydrogenated dry gas enters the liquid phase and is oxidized by the trivalent complex iron ions in the desulfurizer lean liquid to generate sulfur element. The desulfurization liquid containing sulfur element (hereinafter referred to as rich liquid) is sent to the rich liquid flash evaporation part. The purified dry gas after desulfurization is sent to the purified gas recovery device outside the boundary area via the thirty-third pipeline 133.

[0066] The hydrogen sulfide in the non-condensable gas from the S2.2 and C5+ heavy hydrocarbon buffer tanks 3 is first neutralized and absorbed by alkali solution to generate divalent sulfur, and then sent to the regeneration tower 8 through the twenty-seventh pipeline 127 by utilizing the high head difference of the alkali solution absorption tank 11, and the divalent sulfur ions are oxidized with the trivalent complex iron ions in the regeneration tower 8 to generate sulfur, which also serves the purpose of replenishing alkali consumption. The qualified non-condensable gas purified by the alkali solution absorption tank 11 is sent to the fuel gas system outside the boundary area through the twenty-eighth pipeline 128 for connection.

[0067] S2.3, when the resin in the high-performance oil-absorbing resin tank 4 is adsorbed to a certain degree and reaches a saturated state, it needs to be regenerated by thermal nitrogen. The nitrogen from the boundary area is first preheated by nitrogen and heat-exchanged with the regeneration gas of about 350-400°C produced by desorption of the resin tank to 150-200°C, and then heated to about 400°C to become hot nitrogen through the fifteenth pipeline 115 to the nitrogen heater 19. The hot nitrogen enters one of the high-performance oil-absorbing resin tanks 4 to be regenerated for heating, regeneration and desorption. The thermally desorbed C5+ component is condensed with the regeneration gas through the nitrogen preheater 20 and the regeneration gas condenser 21 and then enters the C5+ heavy hydrocarbon buffer tank 3 to achieve gas-liquid separation. The sulfur-containing regeneration gas generated by separation is combined with the gas in ② for absorption and desulfurization, and the subsequent sequence is the same as the process in S2.2.

[0068] S3, rich liquid flash evaporation

[0069] The rich liquid with a certain pressure is discharged from the liquid outlet at the bottom of the desulfurization tower 5 and enters the energy recovery device 7 through the eighth pipeline 108, and the residual pressure of the rich liquid flash evaporation is recovered and reused to convert it into electric heating energy of the nitrogen heater 19 to provide hot nitrogen for the high-performance oil-absorbing resin tank 4 to achieve regeneration. The liquid after energy recovery of the rich liquid enters the subsequent regeneration tower 8 through the ninth pipeline 109 to achieve oxidation regeneration of the desulfurizer.

[0070] S4, solution oxidation regeneration

[0071] The sulfur-rich liquid is contacted with the regeneration air bubbled from the air blower 26 in multiple stages in the regeneration tower 8. The ferrous complex is oxidized to ferrous complex by oxygen, and the sulfur particles grow at the same time. The regeneration waste air enters the VOCs purification facility outside the boundary area from the gas outlet at the upper end of the regeneration tower 8 through the thirteenth pipeline 113.

[0072] S5. Sulfur slurry filtration

[0073] Under the action of natural gravity, the sulfur in the regenerated solid-liquid mixture settles to the cone bottom of the regeneration tower 8 for concentration (hereinafter referred to as sulfur slurry), is pumped out from the cone bottom outlet of the regeneration tower 8 by the sulfur slurry pump 24 and sent to the plate and frame filter 9 through the twelfth pipeline 112 to separate the solid sulfur (also called sulfur paste) from the desulfurizer, and the separated filtrate is sent back to the regeneration tower 8 through the filtrate pump 25, and the filtered and separated solid sulfur paste is sent to the sulfur refining part.

[0074] S6, Sulfur Refining

[0075] The filtered sulfur paste enters the sulfur melting kettle 10 through the fourteenth pipeline 114. The sulfur melting kettle 10 adopts a low-pressure steam jacket heating to separate the sulfur and liquid in the sulfur paste. The liquid sulfur produced by melting at the bottom of the sulfur melting kettle 10 is sent out of the boundary to be formed. The exhaust gas generated by the pressure relief of the sulfur melting kettle 10 is sent to the VOCs purification equipment outside the boundary area through the thirtieth pipeline 130.

[0076] In the present invention, the combined process of low-temperature condensation pre-separation + high-performance oil-absorbing resin 16 is used to remove the C5+ component to the greatest extent, ensuring the smooth operation of the subsequent complex iron desulfurization device; the hydraulic turbine energy recovery device 7 is used to recover the desulfurization rich liquid flash evaporation energy as high-performance activated carbon desorption regeneration heat energy, saving public utility power consumption. In addition, the gas-liquid separated dry gas and the liquid C5+ component are both desulfurized by hydrogen through the complex iron device, realizing the resource utilization of refinery hydrogenation dry gas.

[0077] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A complex iron desulfurization device for hydrogenated dry gas, characterized in that: It includes a dry gas condenser (1), a dry gas buffer tank (2), a C5+ heavy hydrocarbon buffer tank (3), a high-performance oil absorption resin tank (4), a desulfurization tower (5), a flash tank (6), and an alkali solution absorption tank (11); The gas inlet of the dry gas condenser (1) receives the hydrogenated dry gas from the hydrogenation device through the first pipeline (101), and the gas outlet of the dry gas condenser (1) is connected to the dry gas buffer tank (2) through the second pipeline (102); the gas outlet of the dry gas buffer tank (2) is connected to the first high-performance oil-absorbing resin tank (401) through the third pipeline (103), and the liquid outlet of the dry gas buffer tank (2) is connected to the C5+ heavy hydrocarbon buffer tank (3) through the fourth pipeline (104). The C5+ heavy hydrocarbon buffer tank (3) is used to flash out a small amount of hydrogen sulfide dissolved in the C5+ liquid, and the flashed sulfur-containing non-condensable gas is sent to the alkali solution absorption tank (11) through the twenty-fifth pipeline (125); The gas outlet of the first high-performance oil-absorbing resin tank (401) is connected to the second high-performance oil-absorbing resin tank (402) through a fifth pipeline (105); the gas outlet of the second high-performance oil-absorbing resin tank (402) is connected to the desulfurization tower (5) through a sixth pipeline (106); The gas outlet of the flash tank (6) is connected to the fuel gas system outside the boundary area through an eleventh pipeline (111).

2. The complex iron desulfurization device for hydrogenated dry gas according to claim 1, characterized in that: It also includes an energy recovery device (7) and a regeneration tower (8), wherein the liquid inlet of the desulfurization tower (5) is connected to the regeneration tower (8) via a seventh pipeline (107), and the liquid outlet of the desulfurization tower (5) is connected to the energy recovery device (7) via an eighth pipeline (108); the liquid outlet of the energy recovery device (7) is connected to the flash tank (6) via a ninth pipeline (109); and the liquid outlet of the flash tank (6) is connected to the regeneration tower (8) via a tenth pipeline (110).

3. The complex iron desulfurization device for hydrogenated dry gas according to claim 2, characterized in that: The liquid outlet of the regeneration tower (8) is connected to the plate-and-frame filter (9) via a twelfth pipeline (112), and the gas outlet of the regeneration tower (8) is connected to the VOCs purification equipment outside the boundary area via a thirteenth pipeline (113); the solid sulfur outlet of the plate-and-frame filter (9) is connected to the sulfur melting kettle (10) via a fourteenth pipeline (114); The liquid sulfur outlet of the sulfur melting kettle (10) is connected to the sulfur forming machine outside the boundary area through the twenty-ninth pipeline (129), and the gas outlet of the sulfur melting kettle (10) is connected to the VOCs purification equipment outside the boundary area through the thirtieth pipeline (130); The lean liquid outlet of the regeneration tower (8) is connected to the desulfurization tower (5) via the lean liquid pump inlet pipeline, the lean liquid pump (22), the thirty-second pipeline (132), the solution heat exchanger (23) and the seventh pipeline (107) in sequence, and the slurry outlet of the regeneration tower (8) is connected to the plate and frame filter (9) via the sulfur slurry pump inlet pipeline, the sulfur slurry pump (24) and the twelfth pipeline (112) in sequence.

4. The complex iron desulfurization device for hydrogenated dry gas according to claim 1, characterized in that: The liquid inlet of the dry gas condenser (1) is connected to the low-temperature cold water supply outside the boundary area through the thirty-fourth pipeline (134), and the liquid outlet of the dry gas condenser (1) is connected to the low-temperature cold water return outside the boundary area through the thirty-fifth pipeline (135).

5. The complex iron desulfurization device for hydrogenated dry gas according to claim 2, characterized in that: The energy recovery device (7) is used to recover and reuse the residual pressure of the rich liquid flash evaporation, and convert it into electric heating energy for the nitrogen heater (19). The nitrogen inlet of the nitrogen heater (19) is connected to the nitrogen preheater (20) through a fifteenth pipeline (115), and the outlet of the nitrogen heater (19) is connected to the high-performance oil-absorbing resin tank (4) through a sixteenth pipeline (116), a seventeenth pipeline (117) and an eighteenth pipeline (118); the nitrogen inlet of the nitrogen preheater (20) is connected to the nitrogen pipeline outside the boundary area through a nineteenth pipeline (119).

6. The complex iron desulfurization device for hydrogenated dry gas according to claim 1, characterized in that: The liquid level control valve (13) of the desulfurization tower (5) is arranged on the ninth pipeline (109); the pressure control valve 1 (14) of the flash tank (6) is arranged on the eleventh pipeline (111); and the pressure control valve 2 (15) of the C5+ heavy hydrocarbon buffer tank (3) is arranged on the twenty-fifth pipeline (125).

7. The complex iron desulfurization device for hydrogenated dry gas according to claim 1, characterized in that: The filtrate outlet of the plate and frame filter (9) is connected to the regeneration tower (8) via the filtrate pump inlet pipeline, the filtrate pump (25) and the thirty-first pipeline (131).

8. The complex iron desulfurization device for hydrogenated dry gas according to claim 1, characterized in that: The desulfurization tower (5) contains a dry gas distributor (17) inside, and the dry gas distributor (17) inside the desulfurization tower (5) is connected via a sixth pipeline (106); The regeneration tower (8) contains an air distributor (18) inside, and the air distributor (18) inside the regeneration tower (8) is connected to an air fan (26) through an air inlet pipe.

9. A complex iron desulfurization process for hydrogenated dry gas, characterized in that: The process includes the following steps: Pretreatment of hydrogenated dry gas: The hydrogenated dry gas from the hydrogenation unit is transported to the inlet of the dry gas condenser (1) through the first pipeline (101), and most of the C5+ components in the dry gas are cooled down by low-temperature cold water. The dry gas is transported to the dry gas buffer tank (2) through the second pipeline (102) for gas-liquid separation. The dry gas separated at the top enters two high-performance oil-absorbing resin tanks (4) running in series through the third pipeline (103) to achieve deep removal of the C5+ components to less than 0.01V%. The pretreated hydrogenated dry gas enters the network The desulfurization tower (5) of the combined iron desulfurization absorption part; the C5+ liquid separated at the bottom of the dry gas buffer tank (2) flows into the C5+ heavy hydrocarbon buffer tank (3) at normal pressure through the fourth pipeline (104) to flash out a small amount of hydrogen sulfide dissolved in the C5+ liquid; the flashed sulfur-containing non-condensable gas is sent to the alkali liquid absorption tank (11) at a certain alkali liquid height through the twenty-fifth pipeline (125); the C5+ product separated at the bottom of the C5+ heavy hydrocarbon buffer tank (3) is sent out of the boundary area for recovery through the twenty-sixth pipeline (126).

10. The complex iron desulfurization device for hydrogenated dry gas according to claim 9, characterized in that: After the hydrogenation dry gas is pretreated, it is necessary to carry out hydrogen sulfide absorption, rich liquid flash evaporation, solution oxidation regeneration, sulfur slurry filtration and sulfur refining. The specific steps are as follows: Hydrogen sulfide absorption: The gas absorbed by hydrogen sulfide includes: dry gas containing hydrogen sulfide after pretreatment of hydrogenated dry gas; non-condensable gas containing hydrogen sulfide flashed out from the C5+ heavy hydrocarbon buffer tank (3); and regenerated gas containing hydrogen sulfide produced by desorption of the high-performance oil absorption resin tank (4); The hydrogenated dry gas enters the desulfurization tower (5) at a certain liquid level for bubbling absorption. The regenerated lean liquid from the regeneration tower (8) is transported to the desulfurization tower (5) via the lean liquid pump (22) through the thirty-second pipeline (132). The H2S in the hydrogenated dry gas enters the liquid phase and is oxidized by the trivalent complex iron ions in the desulfurizer lean liquid to generate sulfur. The desulfurization liquid containing sulfur, also called rich liquid, is sent to the rich liquid flash evaporation part. The purified dry gas after desulfurization is sent to the purified gas recovery device outside the boundary area via the thirty-third pipeline (133). When the resin in the high-performance oil-absorbing resin tank (4) is adsorbed to a certain degree and reaches a saturated state, it needs to be regenerated by thermal nitrogen. The nitrogen from the boundary area is first heat-exchanged to 150-200°C by a nitrogen preheater and the 350-400°C regeneration gas generated by desorption from the resin tank, and then heated to 400°C to form hot nitrogen through the fifteenth pipeline (115) to the nitrogen heater (19). The hot nitrogen enters one of the high-performance oil-absorbing resin tanks (4) to be regenerated for heating, regeneration and desorption. The thermally desorbed C5+ components are condensed with the regeneration gas through a nitrogen preheater (20) and a regeneration gas condenser (21) and then enter the C5+ heavy hydrocarbon buffer tank (3) to achieve gas-liquid separation. The sulfur-containing regeneration gas generated by separation is combined with the non-condensable gas from the C5+ heavy hydrocarbon buffer tank (3) for absorption and desulfurization. The separated sulfur-containing regeneration gas and the hydrogen sulfide in the non-condensable gas from the C5+ heavy hydrocarbon buffer tank (3) are first neutralized and absorbed by alkali solution to generate divalent sulfur, and then sent to the regeneration tower (8) through the twenty-seventh pipeline (127) by utilizing the high position difference of the alkali solution absorption tank (11), wherein the divalent sulfur ions react with the trivalent complex iron ions in the regeneration tower (8) to generate sulfur, and at the same time, the purpose of replenishing the alkali consumption is also achieved; the qualified non-condensable gas purified by the alkali solution absorption tank (11) is sent to the fuel gas system outside the boundary area through the twenty-eighth pipeline (128) for connection; Rich liquid flash evaporation: The rich liquid with a certain pressure is discharged from the liquid outlet at the bottom of the desulfurization tower (5) and enters the energy recovery device (7) through the eighth pipeline (108). The residual pressure of the rich liquid flash evaporation is recovered and reused, and converted into electric heating energy of the nitrogen heater (19) to provide hot nitrogen for the high-performance oil-absorbing resin tank (4) to achieve regeneration. The liquid after energy recovery of the rich liquid enters the subsequent regeneration tower (8) through the ninth pipeline (109) to achieve oxidation regeneration of the desulfurizer. Solution oxidation regeneration: The sulfur-containing rich liquid is bubbled with regeneration air from the air blower (26) in the regeneration tower (8) for multi-stage contact, the ferrous iron is oxidized by oxygen to ferrous iron, and the sulfur particles grow at the same time. The regeneration waste air is discharged from the gas outlet at the upper end of the regeneration tower (8) through the thirteenth pipeline (113) into the VOCs purification facility outside the boundary area; Sulfur slurry filtration: Under the action of natural gravity, the sulfur in the solid-liquid mixture after regeneration settles to the cone bottom of the regeneration tower (8) and is concentrated to become sulfur slurry. The sulfur slurry pump (24) is pumped out from the cone bottom outlet of the regeneration tower (8) and sent to the plate-frame filter (9) through the twelfth pipeline (112) to realize solid sulfur and separate it from the desulfurizer. The separated filtrate is sent back to the regeneration tower (8) through the filtrate pump (25), and the filtered and separated solid sulfur paste is sent to the sulfur refining part; Sulfur refining: The filtered sulfur paste enters the sulfur melting kettle (10) through the fourteenth pipeline (114). The sulfur melting kettle (10) is heated by a low-pressure steam jacket to separate the sulfur and liquid in the sulfur paste. The liquid sulfur produced by melting at the bottom of the sulfur melting kettle (10) is sent out of the boundary to be formed. The waste gas generated by the pressure relief of the sulfur melting kettle (10) is sent to the VOCs purification equipment outside the boundary area through the thirtieth pipeline (130).

Images