Dry gas desulfurization system

Abstract

The utility model discloses a dry gas removes organic sulfur system. The dry gas removes organic sulfur system includes: low temperature absorption tower, with the dry gas and low temperature absorption oil of hydrogen sulfide removal as feed, in which dry gas and low temperature absorption oil counter current contact, and get rich absorption oil and absorption tail gas after absorption, hydrolytic reactor, with absorption tail gas as feed, in which the carbonyl sulfur in absorption tail gas is hydrolyzed, amine liquid absorption tower, with hydrolytic tail gas and lean amine liquid as feed, and hydrogen sulfide in hydrolytic tail gas is removed by absorption, and gets rich amine liquid and purifying dry gas. The utility model can purify and remove the organic sulfide in dry gas, reduce the organic sulfur content in gas, and then reduce the SO2 content in the flue gas of the heating furnace of each device.

Description

Technical Field

[0001] This utility model belongs to the field of energy-saving technology, specifically, it relates to a dry gas desulfurization system. Background Technology

[0002] In the petroleum refining process, refining units produce a large amount of light hydrocarbon dry gas, mainly composed of hydrocarbons such as methane, ethane, ethylene, propane, and propylene, as well as non-hydrocarbon components such as H2, N2, and sulfides. Sulfides in the dry gas can be divided into two main categories: inorganic sulfur and organic sulfur, with the inorganic sulfur content typically being higher. According to the existing refinery process, the dry gas is usually first pressurized by a compressor before being sent to a desulfurization tower, after which it is fed into the gas pipeline network. Existing desulfurization towers mostly use amine liquid desulfurization, primarily targeting the removal of hydrogen sulfide gas (inorganic sulfur). However, amine liquid desulfurization has very little effect on the removal of organic sulfur, resulting in a high total sulfur content in the gas collected and fed into the gas pipeline network after desulfurization. Gas with a high total sulfur content is sent to the combustion furnace for combustion, leading to a series of problems such as excessive sulfur content in the flue gas, high acid dew point temperature in the flue gas, increased heat loss in the exhaust gas, and reduced furnace thermal efficiency.

[0003] Patent CN116286089A discloses a dry gas desulfurization device and method. This method involves setting up a mercaptan conversion tower and a diesel absorption desulfurization tower. A mercaptan conversion agent is placed in the mercaptan conversion tower, and packing, a coalescing separator, and a liquid distributor are installed in the diesel absorption tower. This two-step desulfurization process efficiently removes organic sulfur from dry gas. First, the dry gas passes through the mercaptan conversion tower where, under the action of oxygen and the mercaptan conversion agent, the methanethiol in the dry gas is converted to dimethyl disulfide. Simultaneously, hydrogen sulfide is converted to elemental sulfur and adsorbed into the micropores of the mercaptan conversion agent. Then, an alkali is used to wash away the elemental sulfur from the mercaptan conversion agent. Further, the dimethyl disulfide in the dry gas is removed by diesel absorption and washing. However, this process not only generates waste alkali and solid waste pollutants but also contains other organic sulfur compounds besides mercaptans, such as carbonyl sulfur, which are difficult to convert and treat. Utility Model Content

[0004] To address the problem of high organic sulfur content in dry gas leading to high total sulfur levels in the gas pipeline network in existing technologies, this invention provides a dry gas organic sulfur removal system. This system purifies and removes organic sulfur compounds from dry gas, reducing the organic sulfur content in the gas and consequently lowering the SO2 content in the flue gas emitted from the heating furnaces of subsequent units, ensuring the safe, environmentally friendly, efficient, and stable operation of all heating furnaces in the plant.

[0005] According to the purpose of this invention, this utility model provides a dry gas desulfurization system.

[0006] Specifically, the dry gas desulfurization system includes:

[0007] The low-temperature absorption tower uses dry gas that has been pre-treated with hydrogen sulfide in an amine absorption tower and low-temperature absorption oil as feed. The dry gas and low-temperature absorption oil (lean absorption oil) are in countercurrent contact to efficiently absorb organic sulfides such as mercaptans, sulfides, dimethyl disulfide, and thiophene in the dry gas. After absorption, rich absorption oil and absorption tail gas are obtained.

[0008] A hydrolysis reactor is provided, which takes absorption tail gas as feed and hydrolyzes carbonyl sulfide in the absorption tail gas to obtain hydrolyzed tail gas containing hydrogen sulfide; a fixed bed of hydrolysis catalyst is provided in the hydrolysis reactor.

[0009] The amine absorption tower uses hydrolysis tail gas and lean amine liquid as feed. The lean amine liquid is used to absorb and remove hydrogen sulfide from the hydrolysis tail gas. After the hydrolysis tail gas is absorbed in the amine absorption tower, rich amine liquid and purified dry gas are obtained.

[0010] Furthermore, the hydrogen sulfide content in the dry gas pre-treated by the amine absorption tower is generally 20-400 mg / m³. 3 .

[0011] Furthermore, the low-temperature absorption tower is a packed tower. The low-temperature absorption tower includes a dry gas inlet and a rich absorbent oil outlet at the bottom, and a lean absorbent oil inlet and an absorption tail gas outlet at the top. The operating temperature of the low-temperature absorption tower is 10–20℃, the absorption pressure is 0.7–1.5 MPaG, and the absorption liquid-to-gas ratio is 40–200 L / m³. 3 The preferred liquid-to-gas ratio is 60–100 L / m³. 3 .

[0012] Furthermore, the hydrolysis reactor includes a bottom absorption tail gas inlet and a top hydrolysis tail gas outlet. A fixed bed of hydrolysis catalyst is installed inside the reactor to catalyze the carbonyl sulfide hydrolysis reaction. The water content in the dry gas entering the hydrolysis reactor is generally controlled at 0.1–0.5 v%. The water content in the dry gas is adjusted by regulating the amount of steam added to the reactor. The reaction temperature of the hydrolysis reactor is 120–130℃, the operating pressure is generally 0.7–1.5 MPaG, and the gas hourly space velocity is 500–1200 h⁻¹. -1 After treatment in a hydrolysis reactor, the conversion efficiency of carbonyl sulfur in the dry gas can reach over 98%.

[0013] Furthermore, the amine absorption tower can be a packed tower or a plate tower. The amine absorption tower includes a hydrolysis tail gas inlet at the bottom, a rich amine liquid outlet at the bottom, a lean amine liquid inlet at the top, and a purified dry gas outlet at the top.

[0014] Furthermore, the desulfurization system also includes a dry gas heat exchanger for heat exchange between the absorption tail gas and the feed dry gas from the low-temperature absorption tower. Specifically, a dry gas pipeline connects to the hot material inlet of the dry gas heat exchanger, and the hot material outlet of the dry gas heat exchanger connects to the dry gas inlet at the bottom of the low-temperature absorption tower; the absorption tail gas outlet at the top of the low-temperature absorption tower connects to the cold material inlet of the dry gas heat exchanger, and the cold material outlet of the dry gas heat exchanger connects to the cold material inlet of the absorption tail gas heat exchanger. Heat exchange occurs between the feed dry gas and the absorption tail gas within the dry gas heat exchanger, raising the temperature of the absorption tail gas to 20–30°C.

[0015] Furthermore, the desulfurization system also includes an absorbent oil heat exchanger and a cooler. The absorbent oil heat exchanger is used for heat exchange between the rich and lean absorbent oil; the cooler is used to further cool the lean absorbent oil after it has been cooled down. The lean absorbent oil pipeline is connected to the hot material inlet of the absorbent oil heat exchanger, the hot material outlet of the absorbent oil heat exchanger is connected to the inlet of the cooler, and the outlet of the cooler is connected to the lean absorbent oil inlet at the upper end of the low-temperature absorption tower. Heat exchange occurs between the lean and rich absorbent oils within the absorbent oil heat exchanger. After the temperature of the lean absorbent oil drops to 30°C, it is further cooled to 10–20°C within the cooler.

[0016] Furthermore, the rich absorbent oil outlet at the bottom of the low-temperature absorption tower is connected to the cold material inlet of the absorption oil heat exchanger via a pipeline, and the cold material outlet of the absorption oil heat exchanger is connected to the rich absorbent oil pipeline.

[0017] Furthermore, the desulfurization system also includes an absorption tail gas heat exchanger and a heater, which are used for heat exchange and heating of the absorption tail gas from the dry gas heat exchanger. The cold material outlet of the absorption tail gas heat exchanger is connected to the cold material inlet of the heater, and the cold material outlet of the heater is connected to the absorption tail gas inlet at the bottom of the hydrolysis reactor.

[0018] Furthermore, the hydrolysis tail gas inlet at the bottom of the amine liquid tower is connected to the hot material outlet of the absorption tail gas heat exchanger via a pipeline, the rich amine liquid outlet at the bottom of the tower is connected to the rich amine liquid pipeline, the lean amine liquid inlet at the top of the tower is connected to the lean amine liquid pipeline, and the purified dry gas outlet at the top of the tower is connected to the purified dry gas pipeline.

[0019] Furthermore, a hydrolysis agent bed is provided inside the hydrolysis reactor. The hydrolysis tail gas outlet at the top of the hydrolysis reactor is connected to the hot material inlet of the absorption tail gas heat exchanger via a pipeline, and the absorption tail gas inlet at the bottom of the hydrolysis reactor is connected to the heater outlet via a pipeline. At the same time, the absorption tail gas inlet is also connected to a steam pipeline to supplement the water vapor required for the hydrolysis reaction.

[0020] Furthermore, the hydrolysate bed in the hydrolysis reactor is a fixed bed. A gas distributor is installed at the bottom of the hydrolysis reactor to uniformly distribute the dry gas and steam mixture entering the reactor.

[0021] In this invention, carbonyl sulfide is converted into hydrogen sulfide in a hydrolysis reactor under the action of a hydrolyzing agent, yielding hydrolysis tail gas. The absorption tail gas inlet at the bottom of the hydrolysis reactor is connected to the heater outlet and a steam pipe, while the hydrolysis tail gas outlet at the top of the reactor is connected to the hot material inlet of the absorption tail gas heat exchanger. The hot material outlet of the absorption tail gas heat exchanger is connected to the hydrolysis tail gas inlet at the bottom of the amine absorption tower. The hydrogen sulfide-rich hydrolysis tail gas is countercurrently absorbed with lean amine liquid in the amine absorption tower to remove hydrogen sulfide from the hydrolysis tail gas, yielding purified dry gas and rich amine liquid. The rich amine liquid outlet at the bottom of the amine absorption tower is connected to a rich amine liquid pipeline, the lean amine liquid inlet at the top of the amine absorption tower is connected to a lean amine liquid pipeline, and the purified dry gas outlet at the top of the amine absorption tower is connected to a purified dry gas pipeline.

[0022] In this utility model, the cooler, heat exchanger and heater can be in the form of shell and tube heat exchanger, plate heat exchanger, etc., and all of these are well known to those skilled in the art.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. This utility model's dry gas organic sulfur removal system employs a combined technology of low-temperature absorption, hydrolysis, and deep hydrogen sulfide absorption. The dry gas, pre-absorbed with amine solution, first passes through a low-temperature absorption tower to remove organic sulfur (excluding carbonyl sulfide). Then, it passes through a hydrolysis reactor to convert the carbonyl sulfide in the dry gas into hydrogen sulfide. Finally, the hydrogen sulfide is further removed in the amine absorption tower, reducing the sulfide content in the dry gas to 20 mg / m³. 3 The dry gas desulfurization system of this invention significantly reduces the total sulfur content of the gas. It boasts high desulfurization efficiency, improves the properties of the gas, and consequently reduces the SO2 content in the flue gas emitted from the heating furnaces of subsequent units, ensuring the safe, environmentally friendly, efficient, and stable operation of all the plant's heating furnaces.

[0025] 2. In the dry gas desulfurization system of this invention, the combined technology of low-temperature absorption-hydrolysis-hydrogen sulfide deep absorption is a highly efficient recovery technology. Low-temperature absorption can efficiently recover organic sulfides, with an organic sulfur recovery rate of over 98%; organic sulfur hydrolysis can achieve a carbonyl sulfur conversion rate of over 98 mol%; and organic amine absorption can achieve efficient hydrogen sulfide absorption. Therefore, this desulfurization system can efficiently recover sulfur resources.

[0026] 3. In the dry gas desulfurization and organic sulfur removal system of this utility model, the low-temperature absorption-hydrolysis-hydrogen sulfide deep absorption combination technology is a low-energy-consumption, high-efficiency, safe and environmentally friendly recycling technology that does not generate waste. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the dry gas desulfurization process of this utility model.

[0028] Among them, 101-dry gas pipeline, 102-dry gas heat exchanger, 103-low temperature absorption tower, 104-lean absorption oil pipeline, 105-absorption oil heat exchanger, 106-cooler, 107-rich absorption oil pipeline, 108-absorption tail gas heat exchanger, 109-heater, 110-hydrolysis reactor, 111-steam pipeline, 112-amine liquid absorption tower, 113-purified dry gas pipeline, 114-rich amine liquid pipeline, and 115-lean amine liquid pipeline. Detailed Implementation

[0029] The technical solution of this utility model will be further described below with reference to the accompanying drawings, but is not limited to the following embodiments.

[0030] Example 1

[0031] Combination Figure 1 The dry gas desulfurization system of this utility model includes:

[0032] Low-temperature absorption tower 103: The upper part of the low-temperature absorption tower is equipped with a lean absorption oil inlet, the lower part is equipped with a dry gas inlet, and the top and bottom of the low-temperature absorption tower are respectively equipped with an absorption tail gas outlet and a rich absorption oil outlet.

[0033] The lean absorption oil inlet of the low-temperature absorption tower is connected to the lean absorption oil pipeline 104 through a pipeline, cooler 106 and absorption oil heat exchanger 105; the dry gas inlet is connected to the dry gas pipeline 101 through a pipeline and dry gas heat exchanger 102.

[0034] The outlet of the low-temperature absorption tower is connected to the dry gas heat exchanger 102 through a pipeline, where the dry gas is pre-cooled; the outlet of the rich absorbent liquid is connected to the absorbent oil heat exchanger 105 through a pipeline, and then connected to the rich absorbent oil pipeline 107.

[0035] Hydrolysis reactor 110; it uses the absorption tail gas and steam of the low temperature absorption tower as feed, and hydrolyzes organic sulfur such as carbonyl sulfide in it to generate hydrogen sulfide and carbon dioxide.

[0036] The inlet of the hydrolysis reactor 110 is connected to the steam pipe 111 and the absorption tail gas pipe respectively; the absorption tail gas pipe of the low temperature absorption tower is connected to the inlet of the hydrolysis reactor 110 after passing through the dry gas heat exchanger 102, the absorption tail gas heat exchanger 108 and the heater 109 in sequence; wherein, the absorption tail gas heat exchanger 108 is used to exchange heat between the absorption tail gas and the hydrolysis tail gas, and the heater 109 is used to heat the absorption tail gas after heat exchange.

[0037] Amine absorption tower 112: It includes a hydrolysis tail gas inlet at the bottom, a lean amine liquid inlet at the top, a purified gas outlet at the top, and a rich amine liquid outlet at the bottom;

[0038] The hydrolysis tail gas inlet is connected to the hydrolysis tail gas outlet of the hydrolysis reactor via a pipeline and an absorption tail gas heat exchanger; the lean amine liquid inlet is connected to the lean amine liquid pipeline 115; the purified gas outlet is connected to the purified gas pipeline 113; and the rich amine liquid outlet is connected to the rich amine liquid pipeline 114.

[0039] The hydrolysis reactor is equipped with a fixed bed of hydrolysis catalyst to catalyze the hydrolysis reaction of carbonyl sulfur. The hydrolysis reactor 110 can be fed from the top or the bottom.

[0040] Example 2

[0041] Combination Figure 1 The working process of the dry gas desulfurization system of this utility model is as follows:

[0042] The dry gas, which has been pre-treated by the amine absorption tower to remove hydrogen sulfide, enters the lower part of the low-temperature absorption tower after passing through the dry gas pipeline 101 and exchanging heat with the absorption tail gas in the dry gas heat exchanger 102. The lean absorption oil enters the upper part of the low-temperature absorption tower after passing through the lean absorption oil pipeline 104 and exchanging heat with the rich absorption oil in the absorption oil heat exchanger 105, and then being further cooled by the cooler 106. It then enters the upper part of the low-temperature absorption tower and comes into countercurrent contact with the upward-flowing dry gas to remove organic sulfur compounds such as mercaptans, sulfides, dimethyl disulfide, and thiophene from the dry gas. Finally, it is discharged from the absorption tail gas outlet at the top.

[0043] The absorption tail gas from the low-temperature absorption tower first undergoes heat exchange in the dry gas heat exchanger 102, then exchanges heat with the hydrolysis tail gas in the absorption tail gas heat exchanger 108, and finally, after being further heated by the heater 109, it mixes with steam from the steam pipe 111 and enters the hydrolysis reactor 110; under the action of the hydrolysis catalyst, the hydrolysis reaction is carried out; and the hydrolysis tail gas is discharged from the hydrolysis reactor 110.

[0044] After being cooled by the tail gas heat exchanger, the hydrolysis tail gas enters the amine absorption tower 112 from the bottom and comes into countercurrent contact with the lean amine liquid entering from the top of the amine absorption tower to remove the hydrogen sulfide contained in the hydrolysis tail gas. The purified gas is then discharged from the top of the amine absorption tower.

Claims

1. A dry gas desulfurization system, characterized in that, include: The low-temperature absorption tower uses dry gas that has been pre-treated with hydrogen sulfide in an amine absorption tower and low-temperature absorption oil as feed. The dry gas and low-temperature absorption oil are in countercurrent contact to efficiently absorb mercaptans, sulfides, dimethyl disulfide and thiophene in the dry gas. After absorption, rich absorption oil and absorption tail gas are obtained. A hydrolysis reactor is provided, which uses absorption tail gas as feed and hydrolyzes carbonyl sulfide and low molecular weight mercaptan sulfides in the absorption tail gas to obtain hydrolyzed tail gas containing hydrogen sulfide; a fixed bed of hydrolysis catalyst is provided in the hydrolysis reactor. The amine absorption tower uses hydrolysis tail gas and lean amine liquid as feed. The lean amine liquid is used to absorb and remove hydrogen sulfide from the hydrolysis tail gas. After the hydrolysis tail gas is absorbed in the amine absorption tower, rich amine liquid and purified dry gas are obtained.

2. The dry gas desulfurization system according to claim 1, characterized in that, The low-temperature absorption tower includes a dry gas inlet at the bottom, a rich absorbent oil outlet at the bottom, a lean absorbent oil inlet at the top, and an absorbent tail gas outlet at the top.

3. The dry gas desulfurization system according to claim 1, characterized in that, The hydrolysis reactor includes an absorption tail gas inlet at the bottom and a hydrolysis tail gas outlet at the top.

4. The dry gas desulfurization system according to claim 1, characterized in that, The low-temperature absorption tower is a packed tower; and / or, the amine liquid absorption tower is a packed tower or a plate tower.

5. The dry gas desulfurization system according to claim 1, characterized in that, The amine absorption tower includes a hydrolysis tail gas inlet at the bottom, a rich amine liquid outlet at the bottom, a lean amine liquid inlet at the top, and a purified dry gas outlet at the top.

6. The dry gas desulfurization system according to claim 1, characterized in that, The dry gas desulfurization system also includes a dry gas heat exchanger, in which the absorption tail gas and raw material dry gas of the low-temperature absorption tower exchange heat.

7. The dry gas desulfurization system according to claim 6, characterized in that, in, The dry gas pipeline connects to the hot material inlet of the dry gas heat exchanger, and the hot material outlet of the dry gas heat exchanger connects to the dry gas inlet at the bottom of the low-temperature absorption tower; the exhaust gas outlet at the top of the low-temperature absorption tower connects to the cold material inlet of the dry gas heat exchanger, and the cold material outlet of the dry gas heat exchanger connects to the cold material inlet of the exhaust gas heat exchanger.

8. The dry gas desulfurization system according to claim 1, characterized in that, The dry gas desulfurization system also includes an absorbent oil heat exchanger and a cooler; the absorbent oil heat exchanger is used for heat exchange between rich absorbent oil and lean absorbent oil; the cooler is used to further cool the lean absorbent oil after it has been cooled.

9. The dry gas desulfurization system according to claim 8, characterized in that, The rich absorbent oil outlet at the bottom of the low-temperature absorption tower is connected to the cold material inlet of the absorbent oil heat exchanger via a pipeline, and the cold material outlet of the absorbent oil heat exchanger is connected to the rich absorbent oil pipeline.

10. The dry gas desulfurization system according to claim 1, characterized in that, The dry gas desulfurization system also includes an absorption tail gas heat exchanger and a heater, which are used for heat exchange and heating of the absorption tail gas from the dry gas heat exchanger.

11. The dry gas desulfurization system according to claim 10, characterized in that, The hydrolysis tail gas outlet at the top of the hydrolysis reactor is connected to the hot material inlet of the absorption tail gas heat exchanger via a pipeline, and the absorption tail gas inlet at the bottom of the hydrolysis reactor is connected to the heater outlet via a pipeline.

12. The dry gas desulfurization system according to claim 3, characterized in that, The absorption tail gas inlet of the hydrolysis reactor is connected to a steam pipeline to supplement the water vapor required for the hydrolysis reaction.

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