CN112824500A - Method and system for removing hydrogen sulfide in liquid hydrocarbon by amine - Google Patents
Method and system for removing hydrogen sulfide in liquid hydrocarbon by amine Download PDFInfo
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- CN112824500A CN112824500A CN201911153172.1A CN201911153172A CN112824500A CN 112824500 A CN112824500 A CN 112824500A CN 201911153172 A CN201911153172 A CN 201911153172A CN 112824500 A CN112824500 A CN 112824500A
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G19/00—Refining hydrocarbon oils in the absence of hydrogen, by alkaline treatment
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G19/00—Refining hydrocarbon oils in the absence of hydrogen, by alkaline treatment
- C10G19/08—Recovery of used refining agents
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
- C10G2300/20—Characteristics of the feedstock or the products
- C10G2300/201—Impurities
- C10G2300/207—Acid gases, e.g. H2S, COS, SO2, HCN
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Abstract
The invention relates to the technical field of liquid hydrocarbon desulfurization of petrochemical enterprises, and discloses a method and a system for removing hydrogen sulfide in liquid hydrocarbon by amine, wherein the method comprises the following steps: the liquid hydrocarbon is subjected to hydrogen sulfide removal through a lean amine liquid in a hydrogen sulfide removal tower, the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is obtained at the tower top, and an amine-rich liquid is obtained at the tower bottom; the liquid hydrocarbon at the top of the hydrogen sulfide removal tower, the desalted water and the first amine-containing water enter a mixer, the mixed solution enters a water-washing separation tank, the top of the water-washing separation tank is washed to obtain purified liquid hydrocarbon, and the bottom of the tank is washed to obtain amine-containing water; feeding the amine-containing water to a mixer or to the upper part of a flash tank gas column; sending the amine-rich liquid to a flash tank, and obtaining flash steam at the top of a flash tank gas column; the liquid in the flash tank enters a solvent regeneration tower after heat exchange, and lean amine liquid is obtained at the bottom of the tower; cooling the lean amine liquid and then feeding the cooled lean amine liquid into the upper part of a hydrogen sulfide removal tower; and cooling the tower top gas, then feeding the cooled tower top gas into a reflux tank, and obtaining the acid gas at the top outlet of the reflux tank. The invention can obviously reduce the content of entrained amine in the purified liquid hydrocarbon and the content of hydrogen sulfide in the purified liquid hydrocarbon, and improve the quality of the purified liquid hydrocarbon product.
Description
Technical Field
The invention relates to the technical field of liquid hydrocarbon desulfurization of petrochemical enterprises, in particular to a method and a system for removing hydrogen sulfide in liquid hydrocarbon by using amine.
Background
The liquid hydrocarbon desulfurizing and refining system is used mainly in eliminating hydrogen sulfide, mercaptan, sulfur and other impurity components from saturated or unsaturated liquid hydrocarbon produced in oil processing unit in oil refinery, and consists of two systems, one for eliminating hydrogen sulfide and one for eliminating mercaptan. The liquid hydrocarbon hydrogen sulfide removal is the first link of a liquid hydrocarbon desulfurization system, generally, amine liquid is used as a desulfurization solvent to remove hydrogen sulfide in liquid hydrocarbon, the desulfurization solvent can be regenerated and recycled, and a purified liquid hydrocarbon product is obtained after treatment, wherein the quality index of the purified liquid hydrocarbon product is that the content of hydrogen sulfide is not more than 20mg/Nm3. The mercaptan removal of the liquid hydrocarbon is the second link of a liquid hydrocarbon desulfurization system and is a subsequent process for removing hydrogen sulfide from the liquid hydrocarbon. The sweetening agent used in the process of sweetening liquid hydrocarbon is 15-20 mass% NaOH alkali liquor, sodium hydroxide firstly reacts with hydrogen sulfide in purified liquid hydrocarbon to generate sodium sulfide and other sodium salts, and non-renewable waste alkali liquor is generated. At present, the content of hydrogen sulfide in purified liquid hydrocarbon treated by a liquid hydrocarbon hydrogen sulfide removal system of most refineries can reach 20mg/Nm3The indexes, but the amine loss of the system is large, fresh amine liquid needs to be supplemented periodically, and meanwhile, the subsequent liquid hydrocarbon sweetening system is high in alkali exchange frequency, large in alkali consumption and large in waste alkali discharge.
Through analysis, hydrogen sulfide and amine are both reasons for large alkali liquor consumption of the liquid hydrocarbon mercaptan removal system. Therefore, the liquid hydrocarbon hydrogen sulfide removal system should further reduce the hydrogen sulfide content and the amount of entrained amine in the purified liquid hydrocarbon, reduce the amine loss per se, and simultaneously create conditions for reducing alkali consumption and waste alkali discharge of the liquid hydrocarbon mercaptan removal system.
In recent years, as the scale of processed oil products is enlarged, the yield of liquid hydrocarbons of many petrochemical enterprises is increased. Along with the increase of the processing capacity of the liquid hydrocarbon desulfurization system, the amount of entrained amine in the product purification liquid hydrocarbon of the hydrogen sulfide removal system is obviously increased, the amine loss amount is increased, and the fresh amine supplement amount and the supplement frequency of the hydrogen sulfide removal system are increased. In addition, the purification of hydrogen sulfide and entrained amine in liquid hydrocarbon can cause a series of problems of alkali liquor pollution and alkali consumption increase of a subsequent mercaptan removal system, and the like, so that the processing capacity of alkali residues matched with a refinery is bottleneck, and the pressure of enterprise production and environmental protection is high. With the continuous strict requirements of national environmental protection regulations, the whole liquid hydrocarbon desulfurization system (including a hydrogen sulfide removal system and a mercaptan removal system) must strictly control the amount of the discharged caustic sludge, and the larger the discharge amount of the caustic sludge is, the higher the subsequent treatment cost of the caustic sludge is, and the larger the environmental protection pressure is.
Disclosure of Invention
The invention aims to provide a method and a system for removing hydrogen sulfide from liquid hydrocarbon by amine, which can solve the problem of large amine loss of a liquid hydrocarbon hydrogen sulfide removal system of a refinery, obviously reduce the entrainment of the impurity amine in the purified liquid hydrocarbon, further reduce the content of the impurity hydrogen sulfide in the purified liquid hydrocarbon and create conditions for reducing the discharge of caustic sludge and saving the treatment cost of the caustic sludge for the subsequent hydrogen sulfide removal system of the refinery by combining various technologies under the condition of less equipment investment, and solve the problems of large alkali consumption and large discharge of the caustic sludge of the subsequent mercaptan removal system caused by purifying the impurity hydrogen sulfide and the amine in the liquid hydrocarbon.
The first aspect of the invention provides a method for removing hydrogen sulfide in liquid hydrocarbon by amine, which comprises the following steps:
a. liquid hydrocarbon enters from the lower part of the hydrogen sulfide removal tower, lean amine liquid enters from the upper part of the hydrogen sulfide removal tower, liquid hydrocarbon at the top of the hydrogen sulfide removal tower is obtained at the tower top, and amine-rich liquid is obtained at the tower bottom;
b. liquid hydrocarbon, desalted water and first amine-containing water at the top of the hydrogen sulfide removal tower enter a mixer from an inlet of the mixer, mixed liquid obtained at an outlet of the mixer enters a water-washing separation tank, a purified liquid hydrocarbon product is obtained at the top of the water-washing separation tank, and first amine-containing water and second amine-containing water are obtained at the bottom of the tank;
c. b, pumping the first amine-containing water obtained in the step b to an inlet of a mixer through a water washing pump, and delivering the second amine-containing water to the upper part of a gas column of a flash tank;
d. b, sending the rich amine liquid obtained in the step a to a flash tank, and obtaining flash steam at the top of a flash tank gas column;
e. liquid in the flash tank is sent to a heat exchanger for heat exchange through a rich liquid pump and then enters a solvent regeneration tower, lean amine liquid is obtained at the bottom of the tower, and gas at the top of the tower is obtained at the top of the tower;
f. e, sequentially sending the lean amine solution obtained in the step e to a heat exchanger and a lean solution cooler through a lean solution pump for cooling, and sending the cooled lean amine solution to the upper part of a hydrogen sulfide removal tower;
g. and e, sending the tower top gas obtained in the step e into a tower top condensing cooler for cooling, then sending the cooled tower top gas into a reflux tank, obtaining an acid gas product at an outlet of the top of the reflux tank, sending the liquid in the reflux tank into a reflux pump, obtaining a first liquid and a second liquid at an outlet of the reflux pump, returning the first liquid to the upper part of the solvent regeneration tower, and taking the second liquid as an acid aquatic product.
The invention provides a hydrogen sulfide system in amine liquid hydrocarbon removal, which comprises a hydrogen sulfide removal tower, a mixer, a water washing separation tank, a water washing pump, a flash tank, a rich liquid pump, a heat exchanger, a solvent regeneration tower, a tower top condensing cooler, a lean liquid pump, a lean liquid cooler, a reflux tank and a reflux pump;
the device comprises a hydrogen sulfide removal tower, a mixer, a flash tank gas column, a flash tank, a gas-phase outlet, a material inlet, a material outlet, a first amine-containing water pipeline, a second amine-containing water pipeline, a water washing pump, a flash tank gas column upper liquid inlet, a desalted water pipeline, a flash tank gas column upper liquid inlet, a flash tank gas phase outlet, a gas-phase outlet, a reflux tank, a first liquid pipeline and a second liquid pipeline, the first liquid pipeline is connected with a reflux port of the solvent regeneration tower through a reflux pump, a tower bottom liquid outlet of the solvent regeneration tower is connected with a shell pass inlet of a heat exchanger through a barren solution pump, and the shell pass outlet of the heat exchanger is connected with a barren amine liquid inlet at the upper part of the hydrogen sulfide removal tower through a barren solution cooler.
The system and the method for removing hydrogen sulfide in liquid hydrocarbon by amine can obviously reduce the content of the amine entrained in the purified liquid hydrocarbon to 0.003 to 0.01kg (amine)/t (liquid hydrocarbon), and reduce the content of the hydrogen sulfide in the purified liquid hydrocarbon to 2 to 5mg/Nm3The method improves the quality of purified liquid hydrocarbon products, and simultaneously can reduce the discharge amount of the alkali residue of the mercaptan removal system by 30-60 percent, correspondingly reduce the treatment cost of the alkali residue and be more environment-friendly.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention.
FIG. 1 is a schematic diagram of a process flow for removing hydrogen sulfide from liquid hydrocarbons with amines according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a conventional process for removing hydrogen sulfide from liquid hydrocarbons.
Description of the reference numerals
Equipment: 11 a hydrogen sulfide removal tower; 12 a mixer; 13 washing the separating tank with water; 14 water washing pump; 15 flash tank; 16 a rich liquor pump; 17 a heat exchanger; 18 solvent regeneration column; 19 overhead condensing cooler; 20 a reflux tank; 21 a reflux pump; 22 a barren liquor pump; 23 lean liquid cooler; 24 coalescing internal pieces; 25 separating the internal part; 26 min of an amine tank;
logistics: 1 a liquid hydrocarbon; 2 purifying liquid hydrocarbon; 3, flash evaporation gas; 4, acid gas; 5, acid water; 6 desalting water.
Detailed Description
In order that the present invention may be more readily understood, the following detailed description of the invention is given with reference to the accompanying drawings and embodiments, which are given by way of illustration only and are not intended to limit the invention.
According to a first aspect of the present invention, there is provided a process for removing hydrogen sulfide from a liquid hydrocarbon by an amine, the process comprising the steps of:
a. liquid hydrocarbon enters from the lower part of the hydrogen sulfide removal tower, lean amine liquid enters from the upper part of the hydrogen sulfide removal tower, liquid hydrocarbon at the top of the hydrogen sulfide removal tower is obtained at the tower top, and amine-rich liquid is obtained at the tower bottom;
b. liquid hydrocarbon, desalted water and first amine-containing water at the top of the hydrogen sulfide removal tower enter a mixer from an inlet of the mixer, mixed liquid obtained at an outlet of the mixer enters a water-washing separation tank, a purified liquid hydrocarbon product is obtained at the top of the water-washing separation tank, and first amine-containing water and second amine-containing water are obtained at the bottom of the tank;
c. b, pumping the first amine-containing water obtained in the step b to an inlet of a mixer through a water washing pump, and delivering the second amine-containing water to the upper part of a gas column of a flash tank;
d. b, sending the rich amine liquid obtained in the step a to a flash tank, and obtaining flash steam at the top of a flash tank gas column;
e. liquid in the flash tank is sent to a heat exchanger for heat exchange through a rich liquid pump and then enters a solvent regeneration tower, lean amine liquid is obtained at the bottom of the tower, and gas at the top of the tower is obtained at the top of the tower;
f. e, sequentially sending the lean amine solution obtained in the step e to a heat exchanger and a lean solution cooler through a lean solution pump for cooling, and sending the cooled lean amine solution to the upper part of a hydrogen sulfide removal tower;
g. and e, sending the tower top gas obtained in the step e into a tower top condensing cooler for cooling, then sending the cooled tower top gas into a reflux tank, obtaining an acid gas product at an outlet of the top of the reflux tank, sending the liquid in the reflux tank into a reflux pump, obtaining a first liquid and a second liquid at an outlet of the reflux pump, returning the first liquid to the upper part of the solvent regeneration tower, and taking the second liquid as an acid aquatic product.
In the invention, the hydrogen sulfide removal tower uses amine liquid (lean amine liquid) as a desulfurization solvent to remove hydrogen sulfide in liquid hydrocarbon. Preferably, the amine-poor liquid contains 20 to 50 wt%, more preferably 25 to 35 wt%, and even more preferably 30 wt% of amine. The hydrogen sulfide removing tower adopts the conventional arrangement in the field, the lower part of the hydrogen sulfide removing tower is provided with a liquid hydrocarbon inlet, the upper part of the hydrogen sulfide removing tower is provided with a lean amine liquid inlet, the top of the hydrogen sulfide removing tower is provided with a liquid hydrocarbon outlet at the top of the hydrogen sulfide removing tower, and the bottom of the hydrogen sulfide removing tower is provided with an rich amine liquid outlet.
According to the invention, the mass flow ratio of the desalted water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower can be 0.01-0.05, and the mass flow ratio of the first amine-containing water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower can be 0.1-0.5. Preferably, the mass flow ratio of the desalted water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is 0.01-0.03, and the mass flow ratio of the first amine-containing water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is 0.25-0.35. More preferably, the mass flow ratio of the desalted water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is 0.02, and the mass flow ratio of the first amine-containing water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is 0.28.
In the present invention, the amine content of the second amine-containing water can be 0.5 to 5 wt%, preferably 1 to 3 wt%, and more preferably 2 wt%.
According to the invention, the operating pressure of the flash tank may be between 0.1 and 0.3MpaG, preferably 0.15 MpaG.
Preferably, the content of amine in the flash gas is not more than 0.001 wt%. More preferably, the amine content of the flash gas is 0.0005 wt%.
According to the invention, the temperature of the cooled lean amine liquid is 0-5 ℃ lower than the temperature of the liquid hydrocarbon entering the hydrogen sulfide removal tower, and is preferably 1 ℃.
The technological parameters of each system component which are not limited in the invention can be selected conventionally according to the prior art, and belong to the conventional technical means.
According to a second aspect of the invention, the invention provides a hydrogen sulfide system in amine-removed liquid hydrocarbon, which comprises a hydrogen sulfide removal tower, a mixer, a water washing separation tank, a water washing pump, a flash tank, a rich liquid pump, a heat exchanger, a solvent regeneration tower, a tower top condensing cooler, a lean liquid pump, a lean liquid cooler, a reflux tank and a reflux pump;
the device comprises a hydrogen sulfide removal tower, a mixer, a flash tank gas column, a flash tank, a gas-phase outlet, a material inlet, a material outlet, a first amine-containing water pipeline, a second amine-containing water pipeline, a water washing pump, a flash tank gas column upper liquid inlet, a desalted water pipeline, a flash tank gas column upper liquid inlet, a flash tank gas phase outlet, a gas-phase outlet, a reflux tank, a first liquid pipeline and a second liquid pipeline, the first liquid pipeline is connected with a reflux port of the solvent regeneration tower through a reflux pump, a tower bottom liquid outlet of the solvent regeneration tower is connected with a shell pass inlet of a heat exchanger through a barren solution pump, and the shell pass outlet of the heat exchanger is connected with a barren amine liquid inlet at the upper part of the hydrogen sulfide removal tower through a barren solution cooler.
In the invention, the water washing separation tank is in a horizontal or vertical container type, and a coalescence internal part and a liquid separation internal part are arranged in the water washing separation tank and close to a purified liquid hydrocarbon outlet. The arrangement of coalescing internals promotes coalescence of droplets from small droplets to large droplets, and the separating internals achieve good separation of the hydrocarbon and aqueous phases.
According to the invention, a liquid separation bag can be arranged on the tank shell of the water washing separation tank.
In the invention, a light phase liquid column can be arranged on the tank shell of the water washing separation tank.
The liquid separation bag and the light phase liquid column are arranged to enable materials to be separated more fully and thoroughly, and the specific structures of the liquid separation bag and the light phase liquid column can be selected conventionally according to the prior art.
According to the invention, the hydrogen sulfide removal tower adopts a plate tower or a packed tower or adopts a fiber membrane vertical reactor type.
According to the invention, the method for removing hydrogen sulfide in liquid hydrocarbon by amine can be realized by the hydrogen sulfide system in liquid hydrocarbon by amine.
The system components not limited in the present invention may be conventionally arranged according to the prior art.
The present invention will be described in detail by way of examples.
Examples
This example illustrates the present invention of a process and system for removing hydrogen sulfide from liquid hydrocarbons.
As shown in fig. 1, the present invention provides a system for removing hydrogen sulfide from liquid hydrocarbon by amine, which comprises a hydrogen sulfide removing tower 11, a mixer 12, a water washing separation tank 13, a water washing pump 14, a flash tank 15, a rich liquid pump 16, a heat exchanger 17, a solvent regeneration tower 18, an overhead condensing cooler 19, a lean liquid pump 22, a lean liquid cooler 23, a reflux tank 20 and a reflux pump 21; the tower top liquid hydrocarbon outlet of the hydrogen sulfide removal tower 11 is connected with the feed inlet of the mixer 12, the material outlet of the mixer 12 is connected with the inlet of the water washing separation tank 13, the tower bottom amine-containing water outlet of the water washing separation tank 13 is connected with a first amine-containing water pipeline and a second amine-containing water pipeline, the first amine-containing water pipeline is connected with the feed pipeline of the mixer 12 through the water washing pump 14, the second amine-containing water pipeline is connected with the upper liquid inlet of the gas column of the flash tank 15, the feed pipeline of the mixer 12 is connected with a desalination water pipeline, the tower bottom amine-rich liquid outlet of the hydrogen sulfide removal tower 11 is connected with the material inlet of the flash tank 15, the liquid outlet of the flash tank 15 is connected with the tube side material inlet of the heat exchanger 17 through the rich liquid pump 16, the tube side material outlet of the heat exchanger 17 is connected with the material inlet of the solvent regeneration tower 18, the tower top gas phase outlet of the solvent regeneration tower 18 is connected with the reflux, the liquid outlet of the reflux tank 20 is divided into a first liquid pipeline and a second liquid pipeline, the first liquid pipeline is connected with the reflux port of the solvent regeneration tower 18 through a reflux pump 21, the tower bottom liquid outlet of the solvent regeneration tower 18 is connected with the shell side inlet of the heat exchanger 17 through a lean liquid pump 22, and the shell side outlet of the heat exchanger 17 is connected with the lean amine liquid inlet at the upper part of the hydrogen sulfide removal tower 11 through a lean liquid cooler 23.
The water wash knockout drum 13 is provided internally with coalescing internals 24 and liquid separating internals 25 near the purified liquid hydrocarbon outlet. The water washing separation tank 13 is in the form of a horizontal vessel. The hydrogen sulfide removal tower 11 adopts a packed tower.
The method for removing hydrogen sulfide in liquid hydrocarbon by using amine is realized by adopting the system, and specifically comprises the following steps:
a. liquid hydrocarbon 1 enters from the lower part of a hydrogen sulfide removal tower 11, lean amine liquid enters from the upper part of the hydrogen sulfide removal tower 11, liquid hydrocarbon at the top of the hydrogen sulfide removal tower is obtained at the tower top, and amine-rich liquid is obtained at the tower bottom;
b. liquid hydrocarbon at the top of the hydrogen sulfide removal tower, desalted water 6 and first amine-containing water enter a mixer 12 from an inlet of the mixer 12, mixed liquid obtained from an outlet of the mixer 12 enters a water-washing separation tank 13, the top of the water-washing separation tank is washed to obtain a purified liquid hydrocarbon 2 product, and first amine-containing water and second amine-containing water are obtained at the bottom of the tank;
c. b, feeding the first amine-containing water obtained in the step b to the inlet of the mixer 12 through a water washing pump 14, and feeding the second amine-containing water to the upper part of the gas column of the flash tank 15;
d. b, feeding the rich amine liquid obtained in the step a into a flash tank 15, and obtaining flash steam 3 at the top of a gas column of the flash tank 15;
e. liquid in the flash tank 15 is sent into a heat exchanger 17 through a rich liquid pump 16 for heat exchange, and then enters a solvent regeneration tower 18 from an outlet of the heat exchanger 17, lean amine liquid is obtained at the bottom of the tower, and gas at the top of the tower is obtained at the top of the tower;
f. e, the lean amine liquid obtained in the step e is sequentially sent to a heat exchanger 17 and a lean liquid cooler 23 through a lean liquid pump 22 for cooling, and the lean amine liquid obtained at the outlet of the lean liquid cooler 23 is sent to the upper part of a hydrogen sulfide removal tower 11;
g. and e, sending the tower top gas obtained in the step e into a tower top condensing cooler 19 for cooling, then sending the cooled tower top gas into a reflux tank 20, obtaining an acid gas 4 product at an outlet of the top of the reflux tank, sending the liquid in the reflux tank 20 into a reflux pump 21, obtaining a first liquid and a second liquid at an outlet of the reflux pump 21, returning the first liquid to the upper part of the solvent regeneration tower 18, and taking the second liquid as an acid water 5 product.
In this example, the content of hydrogen sulfide in the purified liquid hydrocarbon 2 obtained was 4mg/Nm3The amount of entrained amine in the purified liquid hydrocarbon 2 was 0.005kg (amine)/t (liquid hydrocarbon) without increasing the energy consumption of the system.
Comparative example 1
This comparative example is illustrative of an existing liquid hydrocarbon hydrogen sulfide removal system and process.
As shown in fig. 2, the liquid hydrocarbon hydrogen sulfide removal system in the prior art includes a hydrogen sulfide removal tower 11, an amine separation tank 26, a flash tank 15, a rich liquid pump 16, a heat exchanger 17, a solvent regeneration tower 18, an overhead condenser-cooler 19, a lean liquid pump 22, a lean liquid cooler 23, a reflux tank 20, and a reflux pump 21.
The liquid hydrocarbon 1 enters the lower part of a hydrogen sulfide removal tower 11, the lean amine liquid enters the upper part of the hydrogen sulfide removal tower, the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is obtained at the tower top, and the rich amine liquid is obtained at the tower bottom; the liquid hydrocarbon at the top of the hydrogen sulfide removal tower enters an amine separation tank 26, the purified liquid hydrocarbon 2 product is obtained at the top of the amine separation tank, and the liquid at the bottom of the amine separation tank obtained at the bottom of the tank is sent to a material inlet of a flash tank 15; feeding the rich amine liquid obtained from the bottom of the hydrogen sulfide removal tower 11 into a material inlet of a flash tank 15, obtaining flash steam 3 from the top of a gas column of the flash tank 15, and feeding the liquid of the flash tank 15 into a rich liquid pump 16; the rich liquid pump outlet sends rich amine liquid into a heat exchanger 17 for heat exchange, the rich amine liquid enters a solvent regeneration tower 18 from the outlet of the heat exchanger 17, lean amine liquid is obtained at the bottom of the tower, and gas at the top of the tower is obtained at the top of the tower; the lean amine liquid is sent to a lean liquid pump 22, and then enters a heat exchanger 17 and a lean liquid cooler 23 from the outlet of the lean liquid pump 22 for cooling, the lean amine liquid obtained from the outlet of the lean liquid cooler 23 is divided into two parts, one part is sent to the upper part of a hydrogen sulfide removal tower 11, and the other part is sent to the upper part of a gas column of a flash tank 15; the overhead gas of the solvent regeneration tower 18 is sent to an overhead condensing cooler 19 to be cooled and then enters a reflux tank 20, the acidic gas 4 product is obtained at the outlet of the top of the reflux tank, the liquid of the reflux tank 20 enters a reflux pump 21, the first liquid and the second liquid are obtained at the outlet of the reflux pump 21, the first liquid returns to the upper part of the solvent regeneration tower 18, and the second liquid is used as the acidic water 5 product.
In this comparative example, the content of hydrogen sulfide in the resulting purified liquid hydrocarbon 2 was 20mg/Nm3The amount of entrained amine in the purified liquid hydrocarbon 2 was 0.134kg (amine)/t (liquid hydrocarbon).
Compared with the comparative example, the invention is additionally provided with the mixer 12, the water washing separation tank 13 and the water washing pump 14, the injected desalted water 6 and the first amine-containing water are fully mixed with the liquid hydrocarbon at the top of the hydrogen sulfide removal tower through the mixer 12, the amine in the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is promoted to be dissolved into the water phase from the hydrocarbon phase, the coalescence of the liquid drops is promoted to be changed from small liquid drops into large liquid drops through the coalescence internal part 24 in the water washing separation tank 13, the good separation of the hydrocarbon phase and the water phase is realized through the liquid internal part 25, and a certain amount of amine-containing water is discharged to adjust and control the content of impurity amine and hydrogen sulfide in the purified liquid; the second amine-containing water is fed into the upper part of the gas column of the flash tank 15 to replace lean amine liquid to contact with the flash gas 3 in the tank, so that the content of hydrogen sulfide in the flash gas 3 is reduced better, the condition that amine liquid is carried by the flash gas 3 to cause amine loss in a comparative example is avoided, and meanwhile, the energy consumption of the system is not increased.
The system and the method for removing hydrogen sulfide in liquid hydrocarbon by amine can combine a plurality of technologies, and can purify the liquid hydrocarbon 2 from the original hydrogen sulfide content of 20mg/Nm by less equipment investment under the condition of not changing the diameters and supporting facilities of the hydrogen sulfide removing tower 11 and the solvent regeneration tower 183Down to 4mg/Nm3Meanwhile, the content of the amine carried by the purified liquid hydrocarbon 2 is reduced from 0.134kg (amine)/t (liquid hydrocarbon) to 0.005kg (amine)/t (liquid hydrocarbon), the energy consumption of the system is not increased, the hydrogen sulfide removal rate of the liquid hydrocarbon 1 is improved, the amine running loss is reduced, the amine loss can be reduced to 54.18t per year by calculating the treatment capacity of the liquid hydrocarbon 1 by 50t/h, the alkali residue discharge amount of a subsequent liquid hydrocarbon sweetening system can be reduced by 50%, the alkali residue treatment cost is correspondingly reduced, the environment is more friendly, and good environmental protection benefit and economic benefit are obtained.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the illustrated embodiments.
Claims (10)
1. A method for removing hydrogen sulfide in liquid hydrocarbon by amine is characterized by comprising the following steps:
a. liquid hydrocarbon enters from the lower part of the hydrogen sulfide removal tower, lean amine liquid enters from the upper part of the hydrogen sulfide removal tower, liquid hydrocarbon at the top of the hydrogen sulfide removal tower is obtained at the tower top, and amine-rich liquid is obtained at the tower bottom;
b. liquid hydrocarbon, desalted water and first amine-containing water at the top of the hydrogen sulfide removal tower enter a mixer from an inlet of the mixer, mixed liquid obtained at an outlet of the mixer enters a water-washing separation tank, a purified liquid hydrocarbon product is obtained at the top of the water-washing separation tank, and first amine-containing water and second amine-containing water are obtained at the bottom of the tank;
c. b, pumping the first amine-containing water obtained in the step b to an inlet of a mixer through a water washing pump, and delivering the second amine-containing water to the upper part of a gas column of a flash tank;
d. b, sending the rich amine liquid obtained in the step a to a flash tank, and obtaining flash steam at the top of a flash tank gas column;
e. liquid in the flash tank is sent to a heat exchanger for heat exchange through a rich liquid pump and then enters a solvent regeneration tower, lean amine liquid is obtained at the bottom of the tower, and gas at the top of the tower is obtained at the top of the tower;
f. e, sequentially sending the lean amine solution obtained in the step e to a heat exchanger and a lean solution cooler through a lean solution pump for cooling, and sending the cooled lean amine solution to the upper part of a hydrogen sulfide removal tower;
g. and e, sending the tower top gas obtained in the step e into a tower top condensing cooler for cooling, then sending the cooled tower top gas into a reflux tank, obtaining an acid gas product at an outlet of the top of the reflux tank, sending the liquid in the reflux tank into a reflux pump, obtaining a first liquid and a second liquid at an outlet of the reflux pump, returning the first liquid to the upper part of the solvent regeneration tower, and taking the second liquid as an acid aquatic product.
2. The method for removing hydrogen sulfide from liquid hydrocarbon according to claim 1, wherein the amine-lean solution contains 20-50 wt% of amine.
3. The method for removing hydrogen sulfide from amine-containing liquefied hydrocarbon according to claim 1, wherein the mass flow ratio of the desalted water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is 0.01-0.05, and the mass flow ratio of the first amine-containing water to the liquid hydrocarbon at the top of the hydrogen sulfide removal tower is 0.1-0.5.
4. The method of claim 1, wherein the amine-containing water comprises 0.5-5 wt% of amine.
5. The process for removing hydrogen sulfide from liquid hydrocarbons according to claim 1, wherein the flash tank is operated at a pressure of 0.1-0.3 MPaG; the content of amine in the flash evaporation gas is not more than 0.001 wt%.
6. The method of claim 1, wherein the temperature of the lean amine liquid after cooling is 0-5 ℃ lower than the temperature of the liquid hydrocarbon when entering the hydrogen sulfide removal tower.
7. A system for removing hydrogen sulfide in liquid hydrocarbon by amine is characterized by comprising a hydrogen sulfide removing tower, a mixer, a water washing separation tank, a water washing pump, a flash tank, a rich liquid pump, a heat exchanger, a solvent regeneration tower, a tower top condensing cooler, a lean liquid pump, a lean liquid cooler, a reflux tank and a reflux pump;
the device comprises a hydrogen sulfide removal tower, a mixer, a flash tank gas column, a flash tank, a gas-phase outlet, a material inlet, a material outlet, a first amine-containing water pipeline, a second amine-containing water pipeline, a water washing pump, a flash tank gas column upper liquid inlet, a desalted water pipeline, a flash tank gas column upper liquid inlet, a flash tank gas phase outlet, a gas-phase outlet, a reflux tank, a first liquid pipeline and a second liquid pipeline, the first liquid pipeline is connected with a reflux port of the solvent regeneration tower through a reflux pump, a tower bottom liquid outlet of the solvent regeneration tower is connected with a shell pass inlet of a heat exchanger through a barren solution pump, and the shell pass outlet of the heat exchanger is connected with a barren amine liquid inlet at the upper part of the hydrogen sulfide removal tower through a barren solution cooler.
8. The amine removal hydrogen sulfide system of claim 7, wherein the water wash knockout drum is in the form of a horizontal or vertical vessel having internals for coalescing and separating liquid disposed therein proximate the purified liquid hydrocarbon outlet.
9. The system for removing hydrogen sulfide in liquid hydrocarbon by amine according to claim 7 or 8, wherein a liquid separation bag is arranged on a tank shell of the water washing separation tank; the tank shell of the water washing separation tank is provided with a light phase liquid column.
10. The amine liquid hydrocarbon hydrogen sulfide removal system of claim 7, wherein the hydrogen sulfide removal column is a tray column or a packed column, or is in the form of a fiber membrane vertical reactor.
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| GB1428622A (en) * | 1974-03-06 | 1976-03-17 | Stone Webster Eng Corp | Process for removing acid gases from a gas stream |
| GB2102019A (en) * | 1981-06-03 | 1983-01-26 | Cosden Technology | Method for desulphurisation of liquid hydrocarbon streams |
| CN1632072A (en) * | 2004-12-01 | 2005-06-29 | 中国石油天然气股份有限公司 | Combined device for light oil product alkaline extraction-fixed bed catalytic oxidation sweetening |
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