A process for sulfur recovery from ultra-low concentration ammonia-containing acid gas without a reaction furnace
By combining a reactorless process with an ammonia absorption tower, stripping tower, and selective oxidation reactor, and using phosphoric acid absorbent and LS-03 catalyst, the problem of treating ultra-low concentration amino acid-containing gases was solved. This achieved efficient recovery of ammonia and sulfur and compliance with SO2 emission standards, simplified the process flow, and reduced equipment investment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-10-31
- Publication Date
- 2026-07-07
AI Technical Summary
Existing technologies are insufficient to effectively treat amino acid-containing gases with H2S concentrations below 1%, resulting in poor sulfur quality and severe environmental pollution.
A reactor-free process is adopted, which uses a combination of an ammonia absorption tower, a stripping tower, a regeneration tower and a selective oxidation reactor. Phosphoric acid, monoammonium phosphate or diammonium phosphate is used as the absorbent, and combined with LS-03 selective oxidation catalyst to recover ammonia and sulfur, thus avoiding the need for a reactor and incinerator, and achieving selective oxidation of ammonia and H2S.
It achieves efficient recovery of elemental sulfur while recovering ammonia, solves the problem of treating ultra-low concentration acidic gas, ensures that SO2 emissions from sulfur plants meet standards, has a simple process flow, is safe and environmentally friendly, and requires low equipment investment.
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Figure CN117985658B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of sulfur recovery technology and relates to a sulfur recovery process for ultra-low concentration amino acid-containing gas without a reactor. It is applicable to the treatment of amino acid-containing gas with H2S content of less than 1% in industries such as coal chemical industry. Background Technology
[0002] The acidic gases produced by wastewater stripping units in industries such as coal chemical engineering are characterized by low H2S concentration, high CO2 content, and NH3 content. Some acidic gases have an H2S concentration of less than 1%. It is difficult to effectively utilize these acidic gases using conventional sulfur recovery units; generally, only the Lo-cat process can remove H2S, but the sulfur obtained by the Lo-cat process is of poor quality. Alternatively, these acidic gases can be directly passed into an acidic gas flare for incineration into SO2 for emission, but this method severely pollutes the environment.
[0003] Therefore, there is an urgent need for a new sulfur recovery process that does not require a reactor to treat ultra-low concentration amino acid-containing gases to solve the above-mentioned technical problems. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies, the present invention aims to provide a sulfur recovery process for treating ultra-low concentration ammonia-containing gases without a reactor. This process can recover elemental sulfur while recovering ammonia, and is suitable for treating ultra-low concentration ammonia-containing gases with H2S concentrations below 1%. The process has a short flow, is simple to operate, and is widely used in the treatment of ultra-low concentration ammonia-containing acidic gases in industries such as coal chemical industry.
[0005] This invention provides a sulfur recovery process for treating ultra-low concentration amino acid-containing gases without a reactor, comprising:
[0006] (1) Introduce ultra-low concentration acid-containing gas into the bottom of the ammonia absorption tower, fill the ammonia absorption tower with absorbent, absorb the ammonia in the acid gas in the ammonia absorption tower, discharge the rich liquid after absorption from the bottom of the ammonia absorption tower, and discharge the purified gas from the top of the ammonia absorption tower.
[0007] (2) The rich liquid discharged from the bottom of the ammonia absorption tower is sent to the stripping tower to further strip the hydrogen sulfide in the rich liquid. The stripped ammonia-containing rich liquid is discharged from the bottom of the stripping tower and enters the regeneration tower.
[0008] (3) Ammonia and water vapor regenerated in the regeneration tower are discharged through the top of the regeneration tower and then cooled to obtain ammonia water; the regenerated lean liquid is discharged from the bottom of the regeneration tower and the regenerated lean liquid is returned to the ammonia absorption tower.
[0009] (4) The purified gas discharged from the top of the ammonia absorption tower is heated by the primary heater and then enters the selective oxidation reactor. The gas discharged from the selective oxidation reactor is discharged after recovering sulfur and being alkali washed to meet the standards.
[0010] In step (1), the absorbent includes one or more of phosphoric acid, monoammonium phosphate, or diamine phosphate. If the absorbent is a mixture of two or more of phosphoric acid, monoammonium phosphate, or diamine phosphate, they can be compounded in any proportion. In step (1), the ultra-low concentration amino acid-containing gas is introduced into the bottom of the ammonia absorption tower in two separate routes: one route is directly introduced into the bottom of the ammonia absorption tower, and the other route is introduced into the bottom of the absorption tower after stripping in a stripping tower.
[0011] In step (1), the ultra-low concentration amino acid-containing gas is directly introduced into the bottom of the ammonia absorption tower. At this time, the stripping tower uses inert gas stripping and then introduces it into the bottom of the absorption tower. The inert gas includes one or more of helium, neon, argon, and nitrogen.
[0012] The temperature at the top of the ammonia absorption tower is controlled between 20-45℃, preferably between 25-35℃.
[0013] In step (2), the rich liquid discharged from the bottom of the stripping tower enters the regeneration tower after passing through the rich liquid pump and the lean and rich liquid heat exchanger.
[0014] The top temperature of the stripping tower is controlled between 20-45℃, and the top temperature of the stripping tower is preferably 2-5℃ lower than that of the ammonia absorption tower, so as to avoid water vapor condensing during cooling in the ammonia absorption tower.
[0015] In step (3), the rich regenerated liquid discharged from the bottom of the regeneration tower is returned to the ammonia absorption tower after passing through the lean liquid pump and the rich and lean liquid heat exchanger.
[0016] The bottom of the regeneration tower is preferably heated with steam at 0.1-0.5 MPa (preferably 0.3 MPa), and the steam is preferably water vapor.
[0017] The temperature at the top of the regeneration tower is controlled at 110-125℃, preferably at 115-120℃.
[0018] In step (4), sulfur is recovered from the outlet gas of the oxidation reactor via a sulfur cooler.
[0019] In step (4), the bed temperature of the selective oxidation reactor is controlled at 180-240℃, preferably 190-210℃.
[0020] In step (4), the selective oxidation reactor is filled with a selective oxidation catalyst and α-alumina.
[0021] In this process, the selective oxidation catalyst selectively oxidizes H2S in the previous step to elemental sulfur. The selective oxidation catalyst uses SiO2 as a support and iron as the active component. Preferably, the selective oxidation catalyst is the LS-03 selective oxidation catalyst developed by the Qilu Branch Research Institute of China Petroleum & Chemical Corporation, which is available from Shandong Qilu Keli Chemical Research Institute Co., Ltd. This selective oxidation catalyst is insensitive to water.
[0022] In step (4), the primary heater is one or more of the following methods: medium-pressure steam heating, gas-to-gas heat exchange, high-temperature blending heating, electric heating, or heating furnace (e.g., gas combustion heating furnace, methane combustion heating furnace).
[0023] In step (4), alkaline washing refers to absorbing unreacted hydrogen sulfide, sulfur dioxide and other sulfides with alkaline solution. Alkaline washing can be achieved by setting up an alkaline washing tower or by setting up alkaline washing facilities such as flue gas desulfurization and denitrification.
[0024] The present invention has the following beneficial technical effects:
[0025] (1) The present invention provides a sulfur recovery process for treating ammonia-containing gas without a reactor, which can recover elemental sulfur while recovering ammonia, solve the problem of treating ultra-low concentration acid gas, and can treat ammonia-containing gas with H2S concentration of less than 1%, so that the SO2 emission of the flue gas of the entire sulfur plant meets the standard. The process is short and simple to operate, and can be widely used in the treatment of ultra-low concentration ammonia-containing acid gas in industries such as coal chemical industry.
[0026] (2) The process of the present invention does not use a reactor or incinerator, and is safe and environmentally friendly, with a simple process flow and low equipment investment.
[0027] (3) The process of the present invention can simultaneously treat ammonia, H2S and carbonyl sulfide in acidic gas, and solve the problem of ultra-low concentration acidic gas treatment while recovering ammonia, so that the SO2 emission of the flue gas of the entire sulfur plant meets the emission standards. The content of each component in the emission gas is: ammonia 0-50 vol%, H2S 0-1 vol%, CO2 0-90 vol%, carbonyl sulfide 0-1 vol%. Brief description of the attached figures
[0028] Figure 1 This is a schematic flow diagram of the sulfur recovery process for treating ultra-low concentration amino acid-containing gas without a reactor according to the present invention.
[0029] Figure 2 This is a schematic diagram of the traditional Claus+SCOT sulfur recovery process. Detailed Implementation
[0030] The present invention will now be described in further detail with reference to specific embodiments. However, it should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the claims of this application.
[0031] As an optional furnace-free sulfur recovery process for treating ultra-low concentration amino acid-containing gases according to the present invention, the process is as follows: Figure 1 As shown in the figure, the labels for each item are as follows: 1. Ammonia absorption tower; 2. Stripping tower; 3. Rich liquor pump; 4. Lean and rich liquor heat exchanger; 5. Primary heater; 6. Heat exchanger; 7. Liquid ammonia storage tank; 8. Regeneration tower; 9. Lean liquor pump; 10. Selective oxidation reactor; 11. Sulfur cooler; 12. Alkali washing tower.
[0032] The optional sulfur recovery process for treating ultra-low concentration amino acid-containing gases without a reactor according to the present invention includes:
[0033] (1) The ultra-low concentration amino acid-containing gas is introduced into the bottom of the ammonia absorption tower 1 in two ways. One way is directly introduced into the bottom of the ammonia absorption tower 1, and the other way is introduced into the bottom of the ammonia absorption tower 1 after being stripped by the stripping tower 2. The ammonia absorption tower 1 is filled with absorbent. In the ammonia absorption tower 1, ammonia is absorbed and monoammonium phosphate and / or diammonium phosphate are generated. The rich liquid after absorption is discharged from the bottom of the ammonia absorption tower 1, and the purified gas is discharged from the top of the ammonia absorption tower 1.
[0034] (2) The rich liquid discharged from the bottom of the ammonia absorption tower 1 is sent to the stripping tower 2. After stripping the hydrogen sulfide, it is discharged from the bottom of the stripping tower 2 and enters the regeneration tower 8 after passing through the rich liquid pump 3, the lean and rich liquid heat exchanger 4 and the heat exchanger 6.
[0035] (3) In the regeneration tower 8, diammonium phosphate is heated to decompose monoammonium phosphate and ammonia. Ammonia and water vapor are discharged from the top of the regeneration tower 8 and then cooled to obtain ammonia water. The ammonia water can be sent to the liquid ammonia storage tank 7 for later use. The bottom of the regeneration tower 8 discharges the rich regeneration liquid, which is returned to the ammonia absorption tower 1 after passing through the lean liquid pump 9 and the lean and rich liquid heat exchanger 4.
[0036] (4) The purified gas discharged from the top of the ammonia absorption tower 1 is heated by the primary heater 5 and then enters the selective oxidation reactor 10. The gas from the outlet of the selective oxidation reactor 10 is treated by the sulfur cooler 11 to recover sulfur, and then treated by the alkaline washing tower 12 to meet the standards before being discharged.
[0037] Example 1
[0038] A certain device employs a reactor-free process for sulfur recovery from ultra-low concentration amino acid-containing gas (H2S concentration 0.8%). The ultra-low concentration amino acid-containing gas has a flow rate of 1000m³. 3 The solution is introduced into the bottom of the absorption tower via two routes, one of which is directly introduced into the 600m... 3 400m along the way3 After stripping in the stripping tower, the gas is introduced to the bottom of the ammonia absorption tower, which is filled with phosphoric acid. Ammonia is absorbed, and the top temperature of the ammonia absorption tower is controlled at 36℃. The rich liquid from the bottom of the stripping tower, after absorption, enters the regeneration tower via a rich liquid pump and a lean-rich liquid heat exchanger. The top temperature of the regeneration tower is controlled at 112℃. The ammonia gas and water vapor regenerated at the top of the regeneration tower are cooled to obtain ammonia water. The regenerated rich liquid from the bottom of the regeneration tower is returned to the ammonia absorption tower via a lean liquid pump and a lean-rich liquid heat exchanger. The purified gas from the top of the ammonia absorption tower is heated by a primary medium-pressure steam and then enters the selective oxidation reactor. The selective oxidation reactor is controlled at a bed temperature of 190℃ and is filled with LS-03 selective oxidation catalyst. The outlet gas from the selective oxidation reactor is treated by a sulfur cooler to recover sulfur before entering an alkaline washing tower for alkaline washing to meet emission standards. The SO2 emission from the flue gas is 4 mg / m³. 3 CO emissions 137 mg / m³ 3 .
[0039] Compared to the traditional Claus+SCOT sulfur recovery process, the process in Example 1 solves the problems of ammonia recovery and ensuring that flue gas SO2 emissions meet standards, achieving SO2 emissions of <10mg / m³. 3 It meets the latest environmental protection requirements.
[0040] Example 2
[0041] A certain device employs a reactorless process for sulfur recovery from ultra-low concentration amino acid-containing gas (H2S concentration 0.6%). The ultra-low concentration amino acid-containing gas has a flow rate of 2000m³. 3 All gas is introduced into the bottom of the ammonia absorption tower. Nitrogen stripping is used in the stripping tower before the gas is introduced into the bottom of the ammonia absorption tower. The ammonia absorption tower is filled with a mixture of phosphoric acid and monoammonium phosphate. Ammonia is absorbed, and the top temperature of the ammonia absorption tower is controlled at 32℃. After absorption, the rich liquid at the bottom of the stripping tower enters the regeneration tower via a rich liquid pump and a lean-rich liquid heat exchanger. The top temperature of the regeneration tower is controlled at 116℃. The regenerated ammonia gas and water vapor at the top of the regeneration tower are cooled to obtain ammonia water. The regenerated rich liquid at the bottom of the regeneration tower returns to the ammonia absorption tower via a lean liquid pump and a lean-rich liquid heat exchanger. The purified gas exiting the ammonia absorption tower is heated by primary medium-pressure steam and then enters the selective oxidation reactor. The selective oxidation reactor is controlled at a bed temperature of 195℃ and is filled with LS-03 selective oxidation catalyst. The gas exiting the selective oxidation reactor is treated by a sulfur cooler to recover sulfur before entering the alkaline washing tower for alkaline washing to meet emission standards. The SO2 emission is 8 mg / m³. 3 CO emissions 156 mg / m³ 3 .
[0042] Compared to the traditional Claus+SCOT sulfur recovery process, the process in Example 2 solves the problems of ammonia recovery and ensuring that flue gas SO2 emissions meet standards, achieving SO2 emissions of <10mg / m³. 3 It meets the latest environmental protection requirements.
[0043] Example 3
[0044] A certain device employs a reactorless process for sulfur recovery from ultra-low concentration amino acid-containing gas (H2S concentration 0.4%). The ultra-low concentration amino acid-containing gas has a flow rate of 800m³. 3 The ammonia is introduced into the bottom of the ammonia absorption tower via two routes, one of which is directly introduced into the 500m³ ammonia absorption tower. 3 300m along the way 3 After stripping in the stripping tower, the gas is introduced to the bottom of the ammonia absorption tower, which is filled with phosphoric acid. Ammonia is absorbed, and the top temperature of the ammonia absorption tower is controlled at 27°C. The rich liquid from the bottom of the stripping tower, after absorption, enters the regeneration tower via a rich liquid pump and a lean-rich liquid heat exchanger. The top temperature of the regeneration tower is controlled at 125°C. The ammonia gas and water vapor regenerated at the top of the regeneration tower are cooled to obtain ammonia water. The regenerated rich liquid from the bottom of the regeneration tower is returned to the ammonia absorption tower via a lean liquid pump and a lean-rich liquid heat exchanger. The purified gas from the top of the ammonia absorption tower is heated by a primary electric heater and then enters the selective oxidation reactor. The selective oxidation reactor is controlled at a bed temperature of 205°C and is filled with LS-03 selective oxidation catalyst. The outlet gas from the selective oxidation reactor is treated by a sulfur cooler to recover sulfur before entering an alkaline washing tower for alkaline washing to meet emission standards. The SO2 emission from the flue gas is 6 mg / m³. 3 CO emissions 134 mg / m³ 3 .
[0045] Compared to the traditional Claus+SCOT sulfur recovery process, the process in Example 3 solves the problems of ammonia recovery and ensuring that flue gas SO2 emissions meet standards, achieving SO2 emissions of <10mg / m³. 3 It meets the latest environmental protection requirements.
[0046] Example 4
[0047] A certain device employs a reactorless process for sulfur recovery from ultra-low concentration amino acid-containing gas (H2S concentration of 0.2%). The ultra-low concentration amino acid-containing gas has a flow rate of 3000m³. 3 The ammonia is introduced into the bottom of the ammonia absorption tower via two routes, one of which is directly introduced into the 2000m³ ammonia absorption tower. 3 1000m along the way 3 After stripping in the stripping tower, the ammonia solution is introduced to the bottom of the ammonia absorption tower, which is filled with phosphoric acid. The ammonia is absorbed, and the top temperature of the ammonia absorption tower is controlled at 33℃. The rich liquid from the bottom of the stripping tower, after absorption, enters the regeneration tower via a rich liquid pump and a lean-rich liquid heat exchanger. The top temperature of the regeneration tower is controlled at 115℃. The regenerated ammonia gas and water vapor from the top of the regeneration tower are cooled to obtain ammonia water. The regenerated rich liquid from the bottom of the regeneration tower is returned to the ammonia absorption tower via a lean liquid pump and a lean-rich liquid heat exchanger. The purified gas from the top of the ammonia absorption tower is heated by primary medium-pressure steam and then enters the selective oxidation reactor. The selective oxidation reactor is controlled at a bed temperature of 205℃ and is filled with LS-03 selective oxidation catalyst. The outlet gas from the selective oxidation reactor is treated by a sulfur cooler to recover sulfur before entering the alkaline washing tower for alkaline washing to meet emission standards. The SO2 emission from the flue gas is 5 mg / m³. 3 CO emissions 165 mg / m³3 .
[0048] Compared to the traditional Claus+SCOT sulfur recovery process, Example 4 solves the problems of ammonia recovery and ensuring SO2 emissions meet standards, achieving SO2 emissions of <10 mg / m³. 3 Meets the latest environmental protection requirements.
[0049] Example 5
[0050] A certain device employs a reactorless process for sulfur recovery from ultra-low concentration amino acid-containing gas (H2S concentration of 0.4%). The ultra-low concentration amino acid-containing gas has a flow rate of 2000m³. 3 The ammonia is introduced into the bottom of the ammonia absorption tower via two routes, one of which is directly introduced into the 13000m³ ammonia absorption tower. 3 700m along the way 3 After stripping in the stripping tower, the gas is introduced to the bottom of the ammonia absorption tower, which is filled with phosphoric acid. Ammonia is absorbed, and the top temperature of the ammonia absorption tower is controlled at 38℃. The rich liquid from the bottom of the stripping tower, after absorption, enters the regeneration tower via a rich liquid pump and a lean-rich liquid heat exchanger. The top temperature of the regeneration tower is controlled at 118℃. The ammonia gas and water vapor regenerated at the top of the regeneration tower are cooled to obtain ammonia water. The regenerated rich liquid from the bottom of the regeneration tower is returned to the ammonia absorption tower via a lean liquid pump and a lean-rich liquid heat exchanger. The purified gas from the top of the ammonia absorption tower is heated by a primary medium-pressure steam and then enters the selective oxidation reactor. The selective oxidation reactor is controlled at a bed temperature of 198℃ and is filled with LS-03 selective oxidation catalyst. The outlet gas from the selective oxidation reactor is treated by a sulfur cooler to recover sulfur before entering an alkaline washing tower for alkaline washing to meet emission standards. The SO2 emission from the flue gas is 7 mg / m³. 3 CO emissions 140 mg / m³ 3 .
[0051] Compared to the traditional Claus+SCOT sulfur recovery process, Example 5 solves the problems of ammonia recovery and ensuring SO2 emissions meet standards, achieving SO2 emissions of <10 mg / m³. 3 CO emissions less than 200 mg / m³ 3 It meets the latest environmental protection requirements.
[0052] Comparative Example - Traditional Claus+SCOT Sulfur Recovery Process
[0053] The traditional Claus+SCOT process involves a single-stage thermal reaction and a two-stage catalytic reaction, with exhaust gas treatment using a reduction absorption process, resulting in a simplified flow. Figure 2As shown in the attached figures. The meanings of the labels are as follows: 21, sulfur production furnace; 22, waste heat boiler; 23, No. 1 sulfur cooler; 24, liquid sulfur pool; 25, No. 1 heat exchanger; 26, primary reactor; 27, No. 2 sulfur cooler; 28, No. 2 heat exchanger; 29, secondary reactor; 30, No. 3 sulfur cooler; 31, No. 3 heat exchanger; 32, hydrogenation reactor; 33, tail gas purification unit; 34, incinerator; 35, chimney.
[0054] like Figure 2 As shown, introducing ultra-low concentration and high concentration acid gases into the sulfur-making furnace will result in a lower furnace temperature, incomplete ammonia combustion, and potential blockage of subsequent pipelines. Furthermore, CO2 will be converted into CO within the furnace, leading to high CO levels in the system. Using the traditional Claus+SCOT process, CO emissions are 1000-5000 mg / m³. 3 The CO emissions are significantly higher than those of the present invention.
[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A sulfur recovery process for treating ultra-low concentration amino acid-containing gases without a reactor, comprising: (1) Introduce ultra-low concentration acid-containing gas into the bottom of the ammonia absorption tower, fill the ammonia absorption tower with absorbent, absorb the ammonia in the acid gas in the ammonia absorption tower, discharge the rich liquid after absorption from the bottom of the ammonia absorption tower, and discharge the purified gas from the top of the ammonia absorption tower. (2) The rich liquid discharged from the bottom of the ammonia absorption tower is sent to the stripping tower to further strip the hydrogen sulfide in the rich liquid. The stripped ammonia-containing rich liquid is discharged from the bottom of the stripping tower and enters the regeneration tower. (3) Ammonia and water vapor regenerated in the regeneration tower are discharged from the top of the regeneration tower and then cooled to obtain ammonia water; The regenerated lean liquor is discharged from the bottom of the regeneration tower and returned to the ammonia absorption tower. (4) The purified gas discharged from the top of the ammonia absorption tower is heated by the primary heater and then enters the selective oxidation reactor. The gas discharged from the selective oxidation reactor is discharged after recovering sulfur and being alkali washed to meet the standards. In step (1), the absorbent includes one or more of phosphoric acid, monoammonium phosphate, or diammonium phosphate; in step (1), the ultra-low concentration amino acid-containing gas is introduced into the bottom of the ammonia absorption tower in two separate ways, one of which is directly introduced into the bottom of the ammonia absorption tower, and the other is introduced into the bottom of the absorption tower after further stripping hydrogen sulfide in a stripping tower. The temperature at the top of the ammonia absorption tower is controlled at 20-45℃, and the temperature at the top of the regeneration tower is controlled at 110-125℃. In step (4), the bed temperature of the selective oxidation reactor is controlled at 180-240℃; in step (4), the selective oxidation reactor is filled with selective oxidation catalyst and α-alumina.
2. The sulfur recovery process for low-concentration amino acid-containing gas as described in claim 1, wherein, In step (2), the rich liquid discharged from the bottom of the stripping tower enters the regeneration tower after passing through the rich liquid pump and the lean and rich liquid heat exchanger.
3. The sulfur recovery process for low-concentration amino acid-containing gas as described in claim 1, wherein, In step (3), the rich regenerated liquid discharged from the bottom of the regeneration tower is returned to the ammonia absorption tower after passing through the lean liquid pump and the rich and lean liquid heat exchanger.
4. The sulfur recovery process for low-concentration amino acid-containing gas as described in claim 1, wherein, The bottom of the regeneration tower is heated with 0.1-0.5 MPa steam.
5. The sulfur recovery process for low-concentration amino acid-containing gas as described in claim 1, wherein, In step (4), sulfur is recovered from the outlet gas of the oxidation reactor via a sulfur cooler.