A sulfur recovery process and system with low sulfur emission

Abstract

This invention belongs to the field of sulfur recovery technology, specifically relating to an ultra-low sulfur emission sulfur recovery process and system. The ultra-low sulfur emission sulfur recovery process of this invention includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit. The acidic gas to be treated recovers sulfur through the thermal reaction, catalytic reaction, and tail gas hydrogenation units, and then connects to the deep purification unit. The sulfur recovery process of this invention fully utilizes the existing conditions of the sulfur recovery unit and makes full use of the waste heat of the unit, achieving a stable SO2 emission concentration in the flue gas below 10 mg / m³. 3 All sulfides are recovered and reused in the form of sulfur, with no secondary pollution, meeting the strictest environmental regulations and achieving green and clean operation of the sulfur recovery unit.

Description

Technical Field

[0001] This invention belongs to the field of sulfur recovery technology, specifically relating to a sulfur recovery process and system with ultra-low sulfur emissions. Background Technology

[0002] Sulfur dioxide, also known as sulfurous anhydride, is the most common sulfur oxide and a major component of sulfuric acid feedstock. SO2 can damage the physiological functions of plants and slow down the growth of crops and trees; moreover, inhaling high concentrations of SO2 gas can have a strong irritant effect on the respiratory tract. Furthermore, SO2 is the primary cause of acid rain and has become a major air pollutant that has garnered widespread attention. Therefore, controlling SO2 pollution and reducing SO2 emissions is a crucial task for the sustainable economic and social development of my country.

[0003] In recent years, my country's environmental protection standards have become increasingly stringent. The "Emission Standard of Pollutants for Petroleum Refining Industry (GB31570-2015)" issued in 2015 stipulates that the SO2 emission concentration limit for flue gas from sulfur plants in general areas should reach 400 mg / Nm³. 3 The following are the requirements for key areas: 100 mg / Nm³ 3 The following are currently the strictest standards worldwide. Some provinces and cities in China have further raised the standards beyond the national standards and issued local regulations. Shandong Province has issued the "Regional Integrated Emission Standard for Air Pollutants" (DB37 / 2376—2019), which came into effect in November 2019. This regulation requires that the SO2 emission concentration from sulfur recovery devices in general control areas be lower than 100 mg / Nm³. 3 SO2 emission concentration in key areas is below 50 mg / Nm³ 3 SO2 emission concentration in the core area is below 35 mg / Nm³. 3 .

[0004] Currently, acidic gases produced by the coal chemical and natural gas purification industries are characterized by high CO2 concentrations. In my country, sulfur recovery processes are commonly used to treat these acidic gases. However, due to the anaerobic combustion conditions inside the sulfur-making furnace, the CO2 in the acidic gas reacts within the furnace to produce a large amount of CO gas. The presence of hydrocarbons and oils in the feed gas leads to incomplete combustion of hydrocarbons in the sulfur-making furnace, resulting in a large amount of CO gas as a byproduct. Furthermore, the use of online furnace processes in natural gas purification plants' sulfur recovery units for hydrogen production also contributes to high CO content in Claus tail gas. Many oil refineries introduce high-CO2-concentration acidic gases from coal-to-hydrogen production into their sulfur recovery units, thus resulting in a widespread problem of high CO content in process gases. Currently, sulfur recovery units typically employ a Claus + reduction absorption process. The main factor affecting the SO2 emission concentration in the flue gas is the sulfur-containing compounds in the Claus purification tail gas. Because CO molecules are highly polar, they easily adsorb onto the surface of the catalyst channels, reacting with sulfides such as H2S and SO2 to generate large amounts of COS, resulting in a large amount of unabsorbed COS in the purification tail gas, with concentrations ranging from 100 to 200 mg / Nm³. 3 Unabsorbed COS is converted into SO2 after being burned in an incinerator, increasing the SO2 emission concentration in the flue gas by 70-150 mg / Nm³. 3 Reducing SO2 emission concentration in flue gas requires reducing COS content in the purified exhaust gas. However, current sulfur recovery technologies cannot ensure that sulfur compounds in the emitted flue gas meet emission standards. To meet increasingly stringent environmental regulations, there is an urgent need to develop ultra-low sulfur emission sulfur recovery processes.

[0005] Chinese patent CN112648628A discloses an ultra-low sulfur emission process for a sulfur recovery device. The process involves feeding acidic gas and air into a sulfur-producing reactor to separate liquid sulfur from the reacted gas. The separated gas is then heated and fed back into a reactor for further separation of liquid sulfur. The separated gas is then fed into a hydrogenation reactor, where elemental sulfur and SO2 are hydrogenated to H2S, and the H2S is absorbed by amine solution. The heated gas is then fed into a hydrolysis reactor where an adsorbent is used to adsorb the H2S. Finally, the gas is incinerated in a furnace before being discharged. This process ensures that the SO2 emission concentration in the flue gas remains consistently below 10 mg / Nm³. 3 However, this process requires the addition of an H2S adsorption unit and its supporting catalysts and equipment, making the sulfur plant process more complicated. Furthermore, the adsorbent in the adsorption tower needs frequent regeneration, is easily depleted, is complex to operate, and has high replacement costs.

[0006] Chinese patent CN109019523A discloses an ultra-low sulfur emission acid gas sulfur recovery process. The main equipment, along the acid gas flow direction, includes a combustion furnace, a primary Claus reactor, a secondary Claus reactor and selective hydrogenation reduction reactor, a selective oxidation reactor, a circulating absorption unit, and a liquid sulfur tank, connected in series. The circulating absorption unit includes an absorption tower, and the circulating absorbent is an alkaline solution and / or a calcium-containing solution, with the main water source being the condensate from the steam contained in the process gas. However, this process still suffers from problems such as complex flow, high construction and operating costs, and severe equipment corrosion. Furthermore, the process generates a large amount of waste alkaline solution, creating new pollution.

[0007] Therefore, developing an ultra-low sulfur emission sulfur recovery process that is particularly suitable for treating acidic gases with high CO2 concentrations and has the advantages of low investment and high sulfur recovery rate to meet increasingly stringent environmental protection requirements is of positive significance. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to provide a sulfur recovery process with ultra-low sulfur emissions. The process is particularly suitable for the treatment of acidic gases with high CO2 concentrations, and can fully recover sulfur resources and reduce sulfur-containing waste gas emissions, so as to solve the problem of high sulfur emissions in the prior art that do not meet environmental protection requirements.

[0009] The second technical problem to be solved by the present invention is to provide a sulfur recovery system with ultra-low sulfur emissions. The system solves the practical problem of sulfur recovery devices failing to meet emission standards and has the advantages of simple operation and strong adaptability.

[0010] To solve the above-mentioned technical problems, the present invention provides a sulfur recovery process for ultra-low sulfur emissions, comprising the following steps:

[0011] (1) Thermal reaction stage

[0012] Acidic gases containing H2S and CO2 are mixed with air and burned. Some of the H2S is burned into SO2 and undergoes the Claus reaction at high temperature to produce elemental sulfur and process gas.

[0013] (2) Catalytic reaction stage

[0014] The process gas generated in the thermal reaction stage undergoes a Claus catalytic conversion reaction under the action of a catalyst to obtain elemental sulfur and Claus tail gas after the reaction.

[0015] (3) Exhaust gas hydrogenation stage

[0016] The Claus tail gas produced in the catalytic reaction stage undergoes a hydrogenation reaction under the action of a hydrogenation catalyst to obtain hydrogenation process gas and hydrogenation tail gas.

[0017] (4) Deep purification stage

[0018] The hydrogenated tail gas is partially purified after absorbing H2S. The organic sulfur in the partially purified tail gas is further hydrolyzed into H2S under the action of a hydrolysis catalyst. The hydrolyzed tail gas is further purified after absorbing H2S and then discharged as ultra-pure tail gas. After incineration, it meets emission standards.

[0019] Specifically, in the ultra-low sulfur emission sulfur recovery process, step (1) includes:

[0020] The combustion step is controlled at a temperature of 900-1400℃, preferably 1100-1350℃;

[0021] In the combustion step, the volume ratio of H2S and SO2 in the sulfur-producing tail gas is controlled to be 2:1;

[0022] Preferably, the process further includes the step of condensing the obtained elemental sulfur to obtain liquid sulfur and separating it from the process gas; preferably, the condensation step temperature is 160-170°C.

[0023] Specifically, in the ultra-low sulfur emission sulfur recovery process, step (2) includes:

[0024] The Claus catalytic conversion reaction includes a primary conversion reaction and a secondary conversion reaction;

[0025] The catalyst loaded in the primary conversion reaction step includes a mixture of a sulfur recovery catalyst with oxygen removal function and a titanium dioxide-based sulfur recovery catalyst with high organic sulfur hydrolysis activity.

[0026] The catalyst loaded in the secondary conversion reaction step includes an alumina-based sulfur production catalyst;

[0027] Preferably, the temperature of the first-stage conversion reaction is controlled at 230-250°C;

[0028] Preferably, the temperature of the secondary conversion reaction is controlled at 210-240°C.

[0029] Preferably, the space velocities of the first-order and / or second-order conversion reactions are controlled independently to be 400-800 h⁻¹. -1 .

[0030] Specifically, in the ultra-low sulfur emission sulfur recovery process, step (3) includes:

[0031] The temperature of the hydrogenation reaction is controlled at 250-300℃;

[0032] The catalyst loaded in the hydrogenation reaction step includes a multifunctional, highly active tail gas hydrogenation catalyst;

[0033] Preferably, the method further includes the step of cooling the hydrogenated tail gas to 25-40°C.

[0034] Specifically, in the ultra-low sulfur emission sulfur recovery process, step (4) includes:

[0035] The H2S absorption step includes a step of using amine liquid as an absorbent;

[0036] The hydrolysis catalyst includes an organic sulfur hydrolysis catalyst;

[0037] Preferably, the method further includes a step of regenerating the amine-rich liquid obtained after absorbing H2S, and a step of returning the acid gas generated during regeneration to step (1) for combustion.

[0038] This invention also discloses a sulfur recovery system with ultra-low sulfur emissions, comprising a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit; wherein,

[0039] The thermal reaction unit comprises sequentially connected components:

[0040] In the sulfur-making furnace, acidic gas containing H2S is partially combusted with air to convert it into SO2, yielding elemental sulfur and sulfur-making tail gas.

[0041] A primary condenser, through which the elemental sulfur is cooled;

[0042] Liquid sulfur is obtained by cooling elemental sulfur in the liquid sulfur pool after passing through the primary condenser.

[0043] The catalytic reaction unit comprises sequentially connected components:

[0044] The sulfur-producing tail gas reacts in the first-stage converter to generate first-stage converter tail gas.

[0045] The exhaust gas from the primary converter is condensed and separated in the secondary condenser, and the elemental sulfur in it enters the liquid sulfur pool to obtain liquid sulfur.

[0046] The tail gas from the first-stage converter, after the elemental sulfur is separated, undergoes a Claus catalytic conversion reaction in the second-stage converter to generate Claus tail gas.

[0047] The Claus exhaust gas enters the third-stage condenser for condensation, and the generated liquid sulfur enters the liquid sulfur pool.

[0048] The tail gas hydrogenation unit comprises sequentially connected components:

[0049] The Claus tail gas after elemental sulfur separation is hydrogenated in the hydrogenation reactor to convert sulfur-containing compounds into H2S, thus obtaining hydrogenated tail gas.

[0050] The hydrogenation tail gas is cooled and de-temperatured in the quench tower.

[0051] The deep purification unit comprises sequentially connected components:

[0052] The hydrogenation tail gas enters the absorption tower to absorb the H2S therein;

[0053] The semi-purified tail gas after absorbing H2S is hydrolyzed in the hydrolysis reactor to hydrolyze the organic sulfur in it into H2S. The resulting hydrolyzed tail gas is returned to the absorption tower for absorption to obtain ultra-purified tail gas.

[0054] The ultra-purified exhaust gas is incinerated and then discharged through the incinerator.

[0055] Specifically, in the ultra-low sulfur emission sulfur recovery system, the catalytic reaction unit further includes:

[0056] A primary heater, connected to the primary converter, wherein the sulfur-producing tail gas is preheated by the primary heater before entering the primary converter for reaction; and,

[0057] A secondary heater is connected to the secondary converter, and the exhaust gas from the primary converter is preheated by the secondary heater before entering the secondary converter for reaction.

[0058] Specifically, in the ultra-low sulfur emission sulfur recovery system, the tail gas hydrogenation unit further includes:

[0059] The exhaust gas heater is connected to the hydrogenation reactor, and the Claus exhaust gas is heated by the exhaust gas heater before entering the hydrogenation reactor for reaction;

[0060] A steam generator, connected to the hydrogenation reactor and the quench tower, is used to cool the hydrogenation tail gas.

[0061] Specifically, in the ultra-low sulfur emission sulfur recovery system, the deep purification unit further includes:

[0062] The separator is connected to the absorption tower, and the semi-purified tail gas is separated in the separator to remove the entrained amine liquid.

[0063] A gas heat exchanger, which is connected to the liquid separator;

[0064] A flue gas heat exchanger, which is connected to the gas heat exchanger, the hydrolysis reactor and the incinerator respectively;

[0065] An air cooler is connected to both the gas heat exchanger and the absorption tower.

[0066] Specifically, the ultra-low sulfur emission sulfur recovery system further includes a regeneration tower in the deep purification unit;

[0067] The regeneration tower is connected to both the absorption tower and the sulfur production furnace.

[0068] The bottom outlet of the regeneration tower is connected to the top inlet of the absorption tower;

[0069] The bottom outlet of the absorption tower is connected to the top inlet of the regeneration tower;

[0070] The middle outlet of the regeneration tower is connected to the middle inlet of the absorption tower.

[0071] As an feasible solution, the present invention provides an ultra-low sulfur emission sulfur recovery process, comprising the following steps:

[0072] (1) Thermal reaction unit

[0073] Acidic gases containing H2S and CO2 are mixed with air and burned in a sulfur-producing furnace. One-third of the H2S is burned into SO2, which undergoes the Claus reaction at high temperature.

[0074] 2H₂S + 3O₂ → 2SO₂ + 2H₂O;

[0075] SO2 + 2H2S → 2H2O + 3S.

[0076] The resulting sulfur-producing furnace exhaust gas contains elemental sulfur which is condensed in a primary condenser and enters the liquid sulfur pool. The process gas then enters the catalytic reaction unit.

[0077] As an feasible option, the combustion temperature of the sulfur-making furnace is controlled at 900-1400℃, preferably 1100-1350℃.

[0078] As an feasible option, the volume ratio of H2S to SO2 in the sulfur production furnace tail gas is 2:1.

[0079] As an feasible option, the tail gas from the sulfur-producing furnace contains elemental sulfur, H2S, SO2, COS, and CS2.

[0080] As an feasible option, the tail gas from the sulfur production furnace is cooled to 160-170°C by a primary condenser, and then the liquid sulfur is separated from the process gas.

[0081] (2) Catalytic reaction unit

[0082] The process gas generated in the thermal reaction unit enters the first-stage and second-stage converters, where it undergoes the following reaction under the action of a catalyst:

[0083] SO2 + 2H2S → 2H2O + 3S;

[0084] COS + H2O → H2S + CO2;

[0085] CS2 + 2H2O → 2H2S + CO2.

[0086] After two stages of Claus catalytic conversion, elemental sulfur is condensed by a condenser and enters the liquid sulfur pool, while the Claus tail gas after the reaction enters the tail gas hydrogenation unit.

[0087] As an feasible option, a primary heater is installed before the primary converter to control the inlet temperature of the primary converter at 230-250℃.

[0088] As an feasible option, a secondary heater is installed before the secondary converter to control the inlet temperature of the secondary converter at 210-240℃.

[0089] As a feasible option, the space velocity of the primary and secondary converters is 400-800 h⁻¹. -1 .

[0090] As an feasible option, the recommended gradation scheme for the first-stage converter is as follows: the upper part is filled with 1 / 3 sulfur recovery catalyst with oxygen removal function, and the lower part is filled with 2 / 3 titanium oxide-based sulfur recovery catalyst with high organic sulfur hydrolysis activity.

[0091] As an feasible option, the secondary converter is entirely filled with alumina-based sulfur production catalyst.

[0092] As an feasible option, the oxygen-leakage-protected sulfur recovery catalyst is preferably the LS-971 catalyst developed by the Research Institute of Sinopec Qilu Branch. This catalyst is used to protect or mitigate sulfation damage to the catalyst caused by oxygen leakage in the process gas, thereby extending the catalyst's service life. Furthermore, the process of removing oxygen leakage generates a large amount of heat of reaction, thus increasing the reaction temperature and facilitating the hydrolysis of organic sulfur.

[0093] As a feasible option, the preferred titanium dioxide-based sulfur recovery catalyst is the LS-981G catalyst developed by the Research Institute of Sinopec Qilu Branch. The LS-981G catalyst exhibits higher catalytic activity for the hydrolysis of organic sulfides and the Claus reaction of H2S with SO2, reaching near thermodynamic equilibrium. It is insensitive to O2 poisoning, and its hydrolysis deactivation rate is slow, maintaining relatively stable organic sulfur hydrolysis activity throughout its service life.

[0094] As a feasible option, the preferred alumina-based sulfur production catalyst is the LS-02 catalyst developed by the Research Institute of Sinopec Qilu Branch. This catalyst exhibits high Claus activity, strong resistance to thermal and hydrothermal aging, uniform particle size, low wear, and high crushing strength, thus ensuring long-term operation. Furthermore, the catalyst has numerous macropores with a bimodal pore structure, allowing the generated sulfur to rapidly exit the catalyst channels, further enhancing its Claus activity and organic sulfur hydrolysis activity.

[0095] As an feasible option, the Claus exhaust gas contains trace elements such as sulfur, H2S, SO2, and sulfides such as COS and CS2.

[0096] (3) Exhaust gas hydrogenation unit

[0097] The Claus tail gas produced by the catalytic reaction unit enters the hydrogenation reactor. Under the action of the hydrogenation catalyst, the elemental sulfur and SO2 carried in the tail gas are completely converted into H2S, and COS and CS2 are hydrolyzed into H2S.

[0098] S x +xH2→xH2S;

[0099] SO2 + 3H2 → H2S + 2H2O.

[0100] As a feasible solution, the hydrogenation process gas is generated, cooled by a steam generator, and then enters a quench tower, while the hydrogenation tail gas enters a deep purification unit.

[0101] As an feasible option, a tail gas heater is installed before the hydrogenation reactor to control the inlet temperature of the hydrogenation reactor at 250-300℃.

[0102] As an feasible option, the hydrogenation reactor is filled with a multifunctional, highly active tail gas hydrogenation catalyst.

[0103] As a feasible option, the preferred multifunctional high-activity tail gas hydrogenation catalyst is the LSH-03G catalyst developed by the Research Institute of Sinopec Qilu Branch. This catalyst exhibits excellent low-temperature hydrogenation and hydrolysis activity, and its unique pore structure distribution facilitates CO desorption, thus giving the catalyst good CO conversion activity. CO undergoes the following reaction on the catalyst:

[0104] CO + H₂O → CO₂ + H₂.

[0105] As an feasible option, the outlet hydrogenation tail gas temperature of the quench tower is 25-40℃, preferably 25-38℃.

[0106] As an feasible option, the hydrogenation tail gas contains H2S and COS.

[0107] As an feasible option, the COS content in the hydrogenation tail gas is 100-200 mg / m³. 3 .

[0108] (4) Deep purification unit

[0109] Hydrogenation tail gas containing H2S and COS enters an amine absorption tower containing a formulated high-efficiency desulfurization solvent. After H2S is absorbed by the semi-lean amine solution, the semi-purified tail gas is extracted from the middle of the absorption tower. After being separated in a separatory tank, it sequentially exchanges heat with the hydrolysis tail gas in a gas heat exchanger and with the flue gas in a flue gas heat exchanger until it reaches the temperature required for the hydrolysis reaction. Then it enters the hydrolysis reactor, where organic sulfur compounds such as COS in the semi-purified tail gas are hydrolyzed into H2S under the action of a hydrolysis catalyst.

[0110] COS + H2O → H2S + CO2.

[0111] As a feasible approach, the hydrolysis tail gas is cooled sequentially by a gas heat exchanger and an air cooler, then returned to the middle of the absorption tower. After H2S is absorbed by the lean amine solution, the rich amine solution is discharged from the bottom of the absorption tower, and the ultra-pure tail gas is discharged from the top. The ultra-pure tail gas enters the incinerator for combustion. The incinerator tail gas exchanges heat with the semi-pure tail gas and is cooled to 250-300℃ before being discharged through the chimney to meet emission standards.

[0112] As an feasible option, the semi-lean amine solution comes from the middle of the regeneration tower.

[0113] As an feasible option, the lean amine solution is derived from the bottom of the regeneration tower.

[0114] As an feasible solution, the regenerated acid gas at the top of the regeneration tower is returned to the sulfur production furnace for recycling and reuse as the acid gas source for the sulfur production unit, thereby realizing a closed-loop cycle of sulfur resources.

[0115] As an feasible option, the temperature at the top of the regeneration tower is controlled at 100-115℃, the temperature at the bottom of the tower is controlled at 115-120℃, and the pressure at the top of the tower is 0.06-0.10 MPa.

[0116] As an feasible option, the amine-rich liquid at the bottom of the absorption tower enters the regeneration tower from the top of the regeneration tower.

[0117] As an feasible solution, the separator is used to separate the amine liquid carried in the semi-purified tail gas.

[0118] As an feasible solution, the semi-purified tail gas after separation carrying amine liquid is heated to 90℃-110℃ by a gas heat exchanger with the hydrolysis tail gas, which can reduce the heat load of the air cooler.

[0119] As an feasible option, the temperature required for the hydrolysis reaction after heat exchange with the flue gas via the flue gas heat exchanger is 110℃~140℃, preferably 120℃~140℃, to prevent the formation of condensate in the hydrolysis reactor.

[0120] As an feasible option, the hydrolysis reactor is filled with LS-05 organic sulfur hydrolysis catalyst, which can ensure that the hydrolysis conversion rate of organic sulfur in the hydrogenation reactor reaches more than 99.5%.

[0121] As a feasible option, the COS content in the ultra-purified exhaust gas is less than 1 mg / m³. 3 .

[0122] The ultra-low sulfur emission sulfur recovery process of this invention includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit. The acidic gas to be treated recovers sulfur through the thermal reaction, catalytic reaction, and tail gas hydrogenation units, and then connects to the deep purification unit. The deep purification unit employs a two-stage absorption and two-stage regeneration combined with COS hydrolysis. The purified gas in the middle section of the absorption tower undergoes a series of heat exchanges and temperature increases before undergoing COS hydrolysis in the hydrolysis reactor. The hydrolysis tail gas is returned to the middle section of the absorption tower for H2S absorption with amine solution. The ultra-purified tail gas obtained at the top of the absorption tower is sent to an incinerator for combustion to achieve ultra-low sulfur emissions. The sulfur recovery process of this invention fully utilizes the existing conditions of the sulfur plant and makes full use of the waste heat of the plant, enabling the SO2 emission concentration of the flue gas from the sulfur recovery unit to be stably below 10 mg / m³. 3 All sulfides are recovered and reused in the form of sulfur, with no secondary pollution, meeting the strictest environmental regulations and achieving green and clean operation of the sulfur recovery unit.

[0123] The ultra-low sulfur emission sulfur recovery system of this invention can significantly reduce SO2 emissions from flue gas. Furthermore, the system fully utilizes existing sulfur treatment plant conditions, employing an absorption tower to treat hydrolysis tail gas. It achieves deep desulfurization of the tail gas through a two-stage absorption and two-stage regeneration combined with organic sulfur hydrolysis technology. Simultaneously, the sulfur recovery system fully utilizes the waste heat of the plant for heat exchange, effectively reducing energy consumption. Compared to commonly used sulfur recovery technologies, this ultra-low sulfur emission sulfur recovery system produces no waste liquid, and the regenerated acid gas generated by the plant is returned to the system, achieving a closed-loop cycle of sulfur resources. It boasts high desulfurization efficiency, is safe and environmentally friendly, and does not generate secondary pollution.

[0124] The ultra-low sulfur emission sulfur recovery system described in this invention is technically simple, has low investment in equipment construction, requires fewer ultra-purification unit devices, and has the advantages of simple operation and control, simple process flow and operation, strong adaptability, and high sulfur recovery rate. It is particularly suitable for the treatment of acidic gases with high CO2 concentrations to meet increasingly stringent environmental protection requirements. It can fully recover sulfur resources, reduce sulfur-containing waste gas emissions, and solve problems such as non-compliance of sulfur recovery devices with emission standards. It can be widely applied to the sulfur recovery requirements of industries such as oil refining, coal chemical industry, petrochemical industry, and natural gas purification, and has positive significance. Attached Figure Description

[0125] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0126] Figure 1 This is a schematic diagram of the ultra-low sulfur emission sulfur recovery system described in this invention;

[0127] Figure 2 This is a schematic diagram of the sulfur recovery system in Comparative Example 1;

[0128] Figure 3 This is a schematic diagram of the sulfur recovery system in Comparative Example 2;

[0129] The reference numerals in the diagram are as follows: 1-Acid gas; 2-Air; 3-Sulfur production furnace; 4-First-stage condenser; 5-First-stage heater; 6-First-stage converter; 7-Second-stage condenser; 8-Second-stage heater; 9-Second-stage converter; 10-Third-stage condenser; 11-Tail gas heater; 12-Hydrogenation reactor; 13-Steam generator; 14-Liquid sulfur pool; 15-Quick cooler; 16-Regeneration tower; 17-Absorption tower; 18-Separating tank; 19-Gas heat exchanger; 20-Flue gas heat exchanger; 21-Hydrolysis reactor; 22-Air cooler; 23-Incinerator; 24-Chimney; 25-Alkali scrubbing tower. Detailed Implementation

[0130] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0131] like Figure 1 The sulfur recovery system shown includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit.

[0132] like Figure 1 The system structure diagram shown includes a sulfur-generating furnace 3, a primary condenser 4, and a liquid sulfur pool 14 connected in sequence.

[0133] In the thermal reaction unit, acidic gas 1 containing H2S and air 2 are partially burned in the sulfur-making furnace 3 to convert into SO2. At high temperature, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160-170°C by the primary condenser 4 and then enters the liquid sulfur pool 14 to obtain liquid sulfur. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0134] like Figure 1 The schematic diagram of the system structure shown indicates that the catalytic reaction unit includes a first-stage heater 5, a first-stage converter 6, a second-stage condenser 7, a second-stage heater 8, a second-stage converter 9, and a third-stage condenser 10 connected in sequence.

[0135] In the catalytic reaction unit, the sulfur-producing furnace tail gas is first heated to 230-250°C by the primary heater 5, and then enters the primary converter 6. Under the action of the catalyst, it reacts to generate primary converter tail gas, which enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The separated primary converter tail gas is heated to 210-240°C by the secondary heater 8 and enters the secondary converter 9 for reaction. Under the action of the catalyst, it undergoes Claus catalytic conversion to generate Claus tail gas. The Claus tail gas enters the tertiary condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0136] like Figure 1 The system structure diagram shown includes a tail gas hydrogenation unit comprising a tail gas heater 11, a hydrogenation reactor 12, a steam generator 13, and a quench tower 15 connected in sequence.

[0137] In the tail gas hydrogenation unit, Claus tail gas is reheated to 230-280°C by tail gas heater 11 and then enters hydrogenation reactor 12. Under the action of hydrogenation catalyst in hydrogenation reactor 12, sulfur-containing compounds are hydrogenated and converted into H2S. Then, the temperature is reduced to 25-38°C by steam generator 13 and quench tower 15, and the hydrogenated tail gas enters the deep purification unit.

[0138] like Figure 1 The system structure diagram shown includes a deep purification unit comprising a regeneration tower 16, an absorption tower 17, a liquid separator 18, a gas heat exchanger 19, a flue gas heat exchanger 20, a hydrolysis reactor 21, an air cooler 22, an incinerator 23, and a chimney 24 connected in sequence.

[0139] In the deep purification unit, the hydrogenation tail gas enters the bottom of the amine absorption tower 17 and countercurrently contacts the semi-lean amine liquid from the middle of the regeneration tower 16 to absorb H2S. The semi-purified tail gas is then extracted from the middle of the absorption tower, separated from the entrained amine liquid in the separator 18, and then heated to 90-110°C by the gas heat exchanger 19, followed by a further heat exchange to 120-140°C by the flue gas heat exchanger 20. It then enters the hydrolysis reactor 21, where the organic sulfur compounds such as COS in the semi-purified tail gas are hydrolyzed into H2S under the action of the hydrolysis catalyst. The hydrolysis tail gas is then cooled sequentially by the gas heat exchanger 19 and the air cooler 22, and then returned to the middle of the absorption tower. After countercurrent contact with the lean amine liquid from the bottom of the regeneration tower 16, the rich amine liquid is discharged from the bottom of the absorption tower and enters the regeneration tower 16 for regeneration. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace for recycling as the acid gas source for the sulfur production unit. The COS content in the ultra-purified tail gas discharged from the top of the absorption tower is less than 1 mg / m³. 3 The ultra-purified exhaust gas enters the incinerator for combustion. The incinerator exhaust gas exchanges heat with the semi-purified exhaust gas, cooling it to 250-300℃ before being discharged through the chimney. Ultimately, this achieves an SO2 emission concentration of less than 10 mg / m³ from the sulfur recovery unit. 3 Its ultra-low sulfur emissions meet the requirements of the most stringent environmental regulations.

[0140] Example 1

[0141] The sulfur recovery process described in this embodiment is based on the attached... Figure 1 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit.

[0142] (1) Thermal reaction unit

[0143] Acidic gas 1 containing 65 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. At 1150℃, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The volume content of sulfur compounds in the process gas at the outlet of primary condenser 4 is: H2S: 7.12%, SO2: 3.49%, organic sulfur: 0.90%. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0144] (2) Catalytic reaction unit

[0145] The tail gas from the sulfur production furnace is first heated to 240°C by the primary heater 5, and then enters the primary converter 6 (reaction conditions: temperature 310°C, space velocity 800 h⁻¹). -1The reactor is filled with 1 / 3 LS-971 catalyst at the top and 2 / 3 LS-981G catalyst at the bottom. Under the action of the catalyst, the primary converter tail gas is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 150℃. The primary converter tail gas after separation is heated to 215℃ by the secondary heater 8 and enters the secondary converter 9 (reaction conditions: temperature 250℃, space velocity 800h). -1 The reactor contains LS-02 catalyst. Under the action of the catalyst, Claus tail gas is generated. Claus tail gas enters the three-stage condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the three-stage condenser 10 is 145℃. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0146] (3) Exhaust gas hydrogenation unit

[0147] Claus exhaust gas is reheated to 240°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The gas is then cooled to 30°C by steam generator 13 and quench tower 15. The COS content in the hydrogenation exhaust gas is 120 mg / m³. 3 The hydrogenated exhaust gas enters the deep purification unit.

[0148] (4) Deep purification unit

[0149] The hydrogenation tail gas enters the bottom of the amine absorption tower 17, where it countercurrently contacts the semi-lean amine liquid from the middle of the regeneration tower 16 to absorb H2S. The semi-purified tail gas is then extracted from the middle of the absorption tower, separated from the entrained amine liquid in the separator 18, and then heated to 95°C by the gas heat exchanger 19, followed by a further heat exchange to 130°C by the flue gas heat exchanger 20. It then enters the hydrolysis reactor 21, where the organic sulfur compounds such as COS in the semi-purified tail gas are hydrolyzed into H2S by the hydrolysis catalyst. The hydrolysis tail gas is then cooled to 35°C by the gas heat exchanger 19 and the air cooler 22, and then returned to the middle of the absorption tower. After countercurrent contact with the lean amine liquid from the bottom of the regeneration tower 16, the rich amine liquid is discharged from the bottom of the absorption tower and enters the regeneration tower 16 for regeneration. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace for recycling as the acid gas source for the sulfur production unit. The COS content in the ultra-purified tail gas discharged from the top of the absorption tower is 0.20 mg / m³. 3 The ultra-purified exhaust gas enters the incinerator for combustion. After heat exchange with the semi-purified exhaust gas and cooling to 260℃, the exhaust gas is discharged through the chimney. Ultimately, the SO2 emission concentration from the sulfur recovery unit can be reduced to less than 10 mg / m³. 3 Ultra-low sulfur emissions, meeting the strictest environmental regulations currently in place, requiring flue gas SO2 to be reduced to 50 mg / m³. 3 The following requirements apply.

[0150] Example 2

[0151] The sulfur recovery process described in this embodiment is based on the attached... Figure 1 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit.

[0152] (1) Thermal reaction unit

[0153] Acidic gas 1 containing 70 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. At 1250℃, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The volume content of sulfur compounds in the process gas at the outlet of primary condenser 4 is: H2S: 6.95%, SO2: 3.66%, organic sulfur: 0.89%. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0154] (2) Catalytic reaction unit

[0155] The tail gas from the sulfur production furnace is first heated to 243°C by the primary heater 5, and then enters the primary converter 6 (reaction conditions: temperature 320°C, space velocity 700 h⁻¹). -1 The reactor is loaded with 1 / 3 LS-971 catalyst at the top and 2 / 3 LS-981G catalyst at the bottom. Under the action of the catalyst, the primary converter tail gas is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 153℃. The primary converter tail gas after separation is heated to 217℃ by the secondary heater 8 and enters the secondary converter 9 (reaction conditions: temperature 254℃, space velocity 700h). -1 The reactor contains LS-02 catalyst. Under the action of the catalyst, Claus tail gas is generated. Claus tail gas enters the three-stage condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the three-stage condenser 10 is 146℃. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0156] (3) Exhaust gas hydrogenation unit

[0157] Claus exhaust gas is reheated to 240°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The gas is then cooled to 30°C by steam generator 13 and quench tower 15. The COS content in the hydrogenation exhaust gas is 150 mg / m³. 3 The hydrogenated exhaust gas enters the deep purification unit.

[0158] (4) Deep purification unit

[0159] The hydrogenation tail gas enters the bottom of the amine absorption tower 17, where it countercurrently contacts the semi-lean amine liquid from the middle of the regeneration tower 16 to absorb H2S. The semi-purified tail gas is then extracted from the middle of the absorption tower, separated from the entrained amine liquid in the separator 18, and then heated to 95°C by the gas heat exchanger 19, followed by a further heat exchange to 130°C by the flue gas heat exchanger 20. It then enters the hydrolysis reactor 21, where the organic sulfur compounds such as COS in the semi-purified tail gas are hydrolyzed into H2S by the hydrolysis catalyst. The hydrolysis tail gas is then cooled to 35°C by the gas heat exchanger 19 and the air cooler 22, and then returned to the middle of the absorption tower. After countercurrent contact with the lean amine liquid from the bottom of the regeneration tower 16, the rich amine liquid is discharged from the bottom of the absorption tower and enters the regeneration tower 16 for regeneration. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace for recycling as the acid gas source for the sulfur production unit. The COS content in the ultra-purified tail gas discharged from the top of the absorption tower is 0.32 mg / m³. 3 The ultra-purified exhaust gas enters the incinerator for combustion. After heat exchange with the semi-purified exhaust gas and cooling to 250℃, the exhaust gas is discharged through the chimney. Ultimately, this achieves an SO2 emission concentration of less than 10 mg / m³ from the sulfur recovery unit. 3 Ultra-low sulfur emissions, meeting the strictest environmental regulations currently in place, requiring flue gas SO2 to be reduced to 50 mg / m³. 3 The following requirements apply.

[0160] Example 3

[0161] The sulfur recovery process described in this embodiment is based on the attached... Figure 1 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit.

[0162] (1) Thermal reaction unit

[0163] Acidic gas 1 containing 70 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. At 1250℃, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The volume content of sulfur compounds in the process gas at the outlet of primary condenser 4 is: H2S: 7.03%, SO2: 3.59%, organic sulfur: 0.92%. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0164] (2) Catalytic reaction unit

[0165] The tail gas from the sulfur production furnace is first heated to 240°C by the primary heater 5, and then enters the primary converter 6 (reaction conditions: temperature 310°C, space velocity 650 h⁻¹). -1The reactor is filled with 1 / 3 LS-971 catalyst at the top and 2 / 3 LS-981G catalyst at the bottom. Under the action of the catalyst, the primary converter tail gas is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 150℃. The primary converter tail gas after separation is heated to 215℃ by the secondary heater 8 and enters the secondary converter 9 (reaction conditions: temperature 250℃, space velocity 650h). -1 The reactor contains LS-02 catalyst. Under the action of the catalyst, Claus tail gas is generated. Claus tail gas enters the three-stage condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the three-stage condenser 10 is 143℃. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0166] (3) Exhaust gas hydrogenation unit

[0167] Claus exhaust gas is reheated to 245°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The gas is then cooled to 35°C by steam generator 13 and quench tower 15. The COS content in the hydrogenation exhaust gas is 170 mg / m³. 3 The hydrogenated exhaust gas enters the deep purification unit.

[0168] (4) Deep purification unit

[0169] The hydrogenation tail gas enters the bottom of the amine absorption tower 17, where it countercurrently contacts the semi-lean amine liquid from the middle of the regeneration tower 16 to absorb H2S. The semi-purified tail gas is then extracted from the middle of the absorption tower, separated from the entrained amine liquid in the separator 18, and then heated to 90°C by the gas heat exchanger 19, followed by a further heat exchange to 125°C by the flue gas heat exchanger 20. It then enters the hydrolysis reactor 21, where the organic sulfur compounds such as COS in the semi-purified tail gas are hydrolyzed into H2S by the hydrolysis catalyst. The hydrolysis tail gas is then cooled to 33°C by the gas heat exchanger 19 and the air cooler 22, and then returned to the middle of the absorption tower. After countercurrent contact with the lean amine liquid from the bottom of the regeneration tower 16, the rich amine liquid is discharged from the bottom of the absorption tower and enters the regeneration tower 16 for regeneration. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace for recycling as the acid gas source for the sulfur production unit. The COS content in the ultra-purified tail gas discharged from the top of the absorption tower is 0.60 mg / m³. 3 The ultra-purified exhaust gas enters the incinerator for combustion. After heat exchange with the semi-purified exhaust gas and cooling to 265℃, the exhaust gas is discharged through the chimney. Ultimately, this achieves an SO2 emission concentration of less than 10 mg / m³ from the sulfur recovery unit. 3 Ultra-low sulfur emissions, meeting the strictest environmental regulations currently in place, requiring flue gas SO2 to be reduced to 50 mg / m³. 3 The following requirements apply.

[0170] Example 4

[0171] The sulfur recovery process described in this embodiment is based on the attached... Figure 1 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit.

[0172] (1) Thermal reaction unit

[0173] Acidic gas 1 containing 75 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. At 1300℃, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 165℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The volume content of sulfur compounds in the process gas at the outlet of primary condenser 4 is: H2S: 6.99%, SO2: 3.58%, organic sulfur: 0.94%. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0174] (2) Catalytic reaction unit

[0175] The tail gas from the sulfur production furnace is first heated to 245°C by the primary heater 5, and then enters the primary converter 6 (reaction conditions: temperature 325°C, space velocity 800 h⁻¹). -1 The reactor is loaded with 1 / 3 LS-971 catalyst at the top and 2 / 3 LS-981G catalyst at the bottom. Under the action of the catalyst, the primary converter tail gas is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 152℃. The primary converter tail gas after separation is heated to 220℃ by the secondary heater 8 and enters the secondary converter 9 (reaction conditions: temperature 252℃, space velocity 800h). -1 The reactor contains LS-02 catalyst. Under the action of the catalyst, Claus tail gas is generated. Claus tail gas enters the three-stage condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the three-stage condenser 10 is 144℃. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0176] (3) Exhaust gas hydrogenation unit

[0177] Claus exhaust gas is reheated to 235°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The gas is then cooled to 29°C by steam generator 13 and quench tower 15. The COS content in the hydrogenation exhaust gas is 159 mg / m³. 3 The hydrogenated exhaust gas enters the deep purification unit.

[0178] (4) Deep purification unit

[0179] The hydrogenation tail gas enters the bottom of the amine absorption tower 17, where it countercurrently contacts the semi-lean amine liquid from the middle of the regeneration tower 16 to absorb H2S. The semi-purified tail gas is then extracted from the middle of the absorption tower, separated from the entrained amine liquid in the separator 18, and then heated to 93°C by the gas heat exchanger 19, followed by a further heat exchange to 129°C by the flue gas heat exchanger 20. It then enters the hydrolysis reactor 21, where the organic sulfur compounds such as COS in the semi-purified tail gas are hydrolyzed into H2S by the hydrolysis catalyst. The hydrolysis tail gas is then cooled to 36°C by the gas heat exchanger 19 and the air cooler 22, and then returned to the middle of the absorption tower. After countercurrent contact with the lean amine liquid from the bottom of the regeneration tower 16, the rich amine liquid is discharged from the bottom of the absorption tower and enters the regeneration tower 16 for regeneration. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace for recycling as the acid gas source for the sulfur production unit. The COS content in the ultra-purified tail gas discharged from the top of the absorption tower is 0.45 mg / m³. 3 The ultra-purified exhaust gas enters the incinerator for combustion. After heat exchange with the semi-purified exhaust gas and cooling to 260℃, the exhaust gas is discharged through the chimney. Ultimately, the SO2 emission concentration from the sulfur recovery unit can be reduced to less than 10 mg / m³. 3 Ultra-low sulfur emissions, meeting the strictest environmental regulations currently in place, requiring flue gas SO2 to be reduced to 50 mg / m³. 3 The following requirements apply.

[0180] Example 5

[0181] The sulfur recovery process described in this embodiment is based on the attached... Figure 1 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit.

[0182] (1) Thermal reaction unit

[0183] Acidic gas 1 containing 60 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. At 1100℃, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 161℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The volume content of sulfur compounds in the process gas at the outlet of primary condenser 4 is: H2S: 6.85%, SO2: 3.33%, organic sulfur: 0.90%. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0184] (2) Catalytic reaction unit

[0185] The tail gas from the sulfur production furnace is first heated to 238°C by the primary heater 5, and then enters the primary converter 6 (reaction conditions: temperature 310°C, space velocity 600 h⁻¹). -1The reactor is loaded with 1 / 3 LS-971 catalyst at the top and 2 / 3 LS-981G catalyst at the bottom. Under the action of the catalyst, the primary converter tail gas is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 151℃. The primary converter tail gas after separation is heated to 216℃ by the secondary heater 8 and enters the secondary converter 9 (reaction conditions: temperature 251℃, space velocity 600h). -1 The reactor contains LS-02 catalyst. Under the action of the catalyst, Claus tail gas is generated. The Claus tail gas enters the three-stage condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the three-stage condenser 10 is 141℃. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0186] (3) Exhaust gas hydrogenation unit

[0187] Claus exhaust gas is reheated to 250°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The gas is then cooled to 33°C by steam generator 13 and quench tower 15. The COS content in the hydrogenation exhaust gas is 147 mg / m³. 3 The hydrogenated exhaust gas enters the deep purification unit.

[0188] (4) Deep purification unit

[0189] The hydrogenation tail gas enters the bottom of the amine absorption tower 17, where it countercurrently contacts the semi-lean amine liquid from the middle of the regeneration tower 16 to absorb H2S. The semi-purified tail gas is then extracted from the middle of the absorption tower, separated from the entrained amine liquid in the separator 18, and then heated to 96°C by the gas heat exchanger 19, followed by a further heat exchange to 132°C by the flue gas heat exchanger 20. It then enters the hydrolysis reactor 21, where the organic sulfur compounds such as COS in the semi-purified tail gas are hydrolyzed into H2S by the hydrolysis catalyst. The hydrolysis tail gas is then cooled to 36°C by the gas heat exchanger 19 and the air cooler 22, and then returned to the middle of the absorption tower. After countercurrent contact with the lean amine liquid from the bottom of the regeneration tower 16, the rich amine liquid is discharged from the bottom of the absorption tower and enters the regeneration tower 16 for regeneration. The regenerated acid gas from the top of the regeneration tower is returned to the sulfur production furnace for recycling as the acid gas source for the sulfur production unit. The COS content in the ultra-purified tail gas discharged from the top of the absorption tower is 0.35 mg / m³. 3 The ultra-purified exhaust gas enters the incinerator for combustion. After heat exchange with the semi-purified exhaust gas and cooling to 255℃, the exhaust gas is discharged through the chimney. Ultimately, this achieves an SO2 emission concentration of less than 10 mg / m³ from the sulfur recovery unit. 3 Ultra-low sulfur emissions, meeting the strictest environmental regulations currently in place, requiring flue gas SO2 to be reduced to 50 mg / m³. 3 The following requirements apply.

[0190] Comparative Example 1:

[0191] The sulfur recovery process described in this comparative example is based on the appendix Figure 1 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit.

[0192] The sulfur recovery process described in this comparative example is the same as that in Example 1, except that the hydrolysis tail gas is not absorbed by the absorption tower 17, but is directly introduced into the incinerator 23 for incineration and then discharged through the chimney 24. The other processes are the same as in Example 1.

[0193] The final SO2 emission concentration from the sulfur plant flue gas was 150 mg / m³. 3 It does not meet the requirements of national environmental protection regulations.

[0194] Comparative Example 2

[0195] The sulfur recovery process described in this comparative example is based on the appendix Figure 2 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a tail gas purification unit.

[0196] (1) Thermal reaction unit

[0197] Acidic gas 1 containing 70 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. At 1250℃, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The volume content of sulfur compounds in the process gas at the outlet of primary condenser 4 is: H2S: 6.95%, SO2: 3.66%, organic sulfur: 0.89%. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0198] (2) Catalytic reaction unit

[0199] The tail gas from the sulfur production furnace is first heated to 243°C by the primary heater 5, and then enters the primary converter 6 (reaction conditions: temperature 320°C, space velocity 700 h⁻¹). -1 The reactor is loaded with 1 / 3 LS-971 catalyst at the top and 2 / 3 LS-981G catalyst at the bottom. Under the action of the catalyst, the primary converter tail gas is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 153℃. The primary converter tail gas after separation is heated to 217℃ by the secondary heater 8 and enters the secondary converter 9 (reaction conditions: temperature 254℃, space velocity 700h). -1The reactor contains LS-02 catalyst. Under the action of the catalyst, Claus tail gas is generated. Claus tail gas enters the three-stage condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the three-stage condenser 10 is 146℃. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0200] (3) Exhaust gas hydrogenation unit

[0201] Claus exhaust gas is reheated to 240°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The gas is then cooled to 30°C by steam generator 13 and quench tower 15. The COS content in the hydrogenation exhaust gas is 150 mg / m³. 3 The hydrogenated exhaust gas enters the exhaust gas purification unit.

[0202] (4) Exhaust gas purification unit

[0203] The hydrogenation tail gas enters the absorption tower 17 and is absorbed by amine liquid. The purified tail gas is then introduced into the incinerator 23 for incineration and then discharged through the chimney 24.

[0204] The final SO2 emission concentration from the sulfur plant flue gas was 278 mg / m³. 3 It does not meet the requirements of national environmental protection regulations.

[0205] Comparative Example 3

[0206] The sulfur recovery process described in this comparative example is based on the appendix Figure 2 The system shown is used in the process, which includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a tail gas purification unit.

[0207] (1) Thermal reaction unit

[0208] Acidic gas 1 containing 70 (v / v)% H2S and air 2 are partially combusted in sulfur-making furnace 3 to convert into SO2. At 1250℃, H2S and SO2 undergo a Claus reaction to generate sulfur-making furnace tail gas. The elemental sulfur in the gas is cooled to 160℃ by primary condenser 4 and then enters liquid sulfur pool 14 to obtain liquid sulfur. The volume content of sulfur compounds in the process gas at the outlet of primary condenser 4 is: H2S: 6.95%, SO2: 3.66%, organic sulfur: 0.89%. The separated sulfur-making furnace tail gas enters the catalytic reaction unit.

[0209] (2) Catalytic reaction unit

[0210] The tail gas from the sulfur production furnace is first heated to 243°C by the primary heater 5, and then enters the primary converter 6 (reaction conditions: temperature 320°C, space velocity 700 h⁻¹). -1The reactor is loaded with 1 / 3 LS-971 catalyst at the top and 2 / 3 LS-981G catalyst at the bottom. Under the action of the catalyst, the primary converter tail gas is generated and enters the secondary condenser 7 for condensation and separation. The elemental sulfur in the gas enters the liquid sulfur pool 14 to obtain liquid sulfur. The outlet temperature of the secondary condenser 7 is 153℃. The primary converter tail gas after separation is heated to 217℃ by the secondary heater 8 and enters the secondary converter 9 (reaction conditions: temperature 254℃, space velocity 700h). -1 The reactor contains LS-02 catalyst. Under the action of the catalyst, Claus tail gas is generated. Claus tail gas enters the three-stage condenser 10 for condensation. The liquid sulfur generated after condensation enters the liquid sulfur pool 14. The outlet temperature of the three-stage condenser 10 is 146℃. The separated Claus tail gas enters the tail gas hydrogenation unit.

[0211] (3) Exhaust gas hydrogenation unit

[0212] Claus exhaust gas is reheated to 240°C by exhaust gas heater 11 and then enters hydrogenation reactor 12. In hydrogenation reactor 12, under the action of a hydrogenation catalyst, sulfur-containing compounds are hydrogenated to H2S. The gas is then cooled to 30°C by steam generator 13 and quench tower 15. The COS content in the hydrogenation exhaust gas is 150 mg / m³. 3 The hydrogenated exhaust gas enters the exhaust gas purification unit.

[0213] (4) Exhaust gas purification unit

[0214] The hydrogenation tail gas enters the absorption tower 17 and is absorbed by the amine liquid. The purified tail gas is then introduced into the incinerator 23 for incineration and then introduced into the flue gas alkaline scrubbing unit. The flue gas enters the alkaline scrubbing tower 25, where SO2 is removed under the action of the alkaline liquid. The flue gas is then discharged through the chimney 24. The resulting saline wastewater is sent to the sewage treatment plant for treatment.

[0215] The final SO2 emission concentration from the sulfur plant flue gas was 35 mg / m³. 3 It meets the requirements of national environmental protection regulations. However, after six months of operation, the device developed severe corrosion, causing it to malfunction and produce saline wastewater that is difficult to treat and requires significant investment in further treatment.

[0216] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A sulfur recovery system with ultra-low sulfur emissions, characterized in that, It includes a thermal reaction unit, a catalytic reaction unit, a tail gas hydrogenation unit, and a deep purification unit; among which, The thermal reaction unit comprises sequentially connected components: In the sulfur-making furnace (3), H2S-containing acidic gas (1) and air (2) are partially combusted and converted into SO2 to obtain elemental sulfur and sulfur-making tail gas; The elemental sulfur is cooled by the primary condenser (4); Liquid sulfur is obtained by cooling elemental sulfur in the liquid sulfur pool (14) after passing through the primary condenser (4). The catalytic reaction unit comprises sequentially connected components: The sulfur-producing tail gas reacts in the first-stage converter (6) to generate first-stage converter tail gas; Secondary condenser (7): The tail gas of the primary converter is condensed and separated in the secondary condenser (7), and the elemental sulfur in it enters the liquid sulfur pool (14) to obtain liquid sulfur; The tail gas from the first-stage converter after the separation of elemental sulfur is subjected to Claus catalytic conversion reaction in the second-stage converter (9) to generate Claus tail gas. The Claus exhaust gas enters the third-stage condenser (10) for condensation, and the generated liquid sulfur enters the liquid sulfur pool (14). The tail gas hydrogenation unit comprises sequentially connected components: The Claus tail gas after elemental sulfur separation is subjected to a hydrogenation reaction in the hydrogenation reactor (12) to convert the sulfur-containing compound into H2S, thereby obtaining hydrogenated tail gas. Quenching tower (15), through which the hydrogenated tail gas is cooled down; The deep purification unit comprises sequentially connected components: The hydrogenated tail gas enters the absorption tower (17) to absorb the H2S therein; The semi-purified tail gas after absorbing H2S is hydrolyzed in the hydrolysis reactor (21) to hydrolyze the organic sulfur in it into H2S. The resulting hydrolyzed tail gas is returned to the absorption tower (17) for absorption to obtain ultra-purified tail gas. The ultra-purified exhaust gas is incinerated and discharged through the incinerator (23); The deep purification unit further includes: Separating tank (18), which is connected to the absorption tower (17), wherein the semi-purified tail gas is separated from the entrained amine liquid in the separating tank (18); A gas heat exchanger (19) is connected to the liquid separator (18); Flue gas heat exchanger (20), which is connected to the gas heat exchanger (19), the hydrolysis reactor (21) and the incinerator (23) respectively; An air cooler (22) is connected to the gas heat exchanger (19) and the absorption tower (17) respectively; The deep purification unit also includes a regeneration tower (16). The regeneration tower (16) is connected to the absorption tower (17) and the sulfur production furnace (3) respectively; The bottom outlet of the regeneration tower (16) is connected to the top inlet of the absorption tower (17); The bottom outlet of the absorption tower (17) is connected to the top inlet of the regeneration tower (16); The central outlet of the regeneration tower (16) is connected to the central inlet of the absorption tower (17).

2. The ultra-low sulfur emission sulfur recovery system according to claim 1, characterized in that, The catalytic reaction unit also includes: A primary heater (5) is connected to the primary converter (6), and the sulfur-producing tail gas is preheated by the primary heater (5) before entering the primary converter (6) for reaction; and, A secondary heater (8) is connected to a secondary converter (9). The exhaust gas from the primary converter is preheated by the secondary heater (8) and then enters the secondary converter (9) for reaction.

3. The ultra-low sulfur emission sulfur recovery system according to claim 1 or 2, characterized in that, The tail gas hydrogenation unit also includes: The tail gas heater (11) is connected to the hydrogenation reactor (12). The Claus tail gas is heated by the tail gas heater (11) and then enters the hydrogenation reactor (12) for reaction. A steam generator (13) is connected to the hydrogenation reactor (12) and the quench tower (15) for cooling the hydrogenation tail gas.

4. A sulfur recovery process with ultra-low sulfur emissions from the sulfur recovery system according to claim 1, characterized in that, Includes the following steps: (1) Thermal reaction stage Acidic gases containing H2S and CO2 are mixed with air and burned. Part of the H2S is converted to SO2 and undergoes a Claus reaction at high temperature to produce elemental sulfur and process gas. The combustion step is controlled at a temperature of 900-1400℃. (2) Catalytic reaction stage The process gas generated in the thermal reaction stage undergoes a Claus catalytic conversion reaction under the action of a catalyst to obtain elemental sulfur and Claus tail gas after the reaction. (3) Exhaust gas hydrogenation stage The Claus tail gas produced in the catalytic reaction stage undergoes a hydrogenation reaction under the action of a hydrogenation catalyst to obtain hydrogenation process gas and hydrogenation tail gas. (4) Deep purification stage The hydrogenated tail gas is partially purified after absorbing H2S. The organic sulfur in the partially purified tail gas is further hydrolyzed into H2S under the action of a hydrolysis catalyst. The hydrolyzed tail gas is further purified after absorbing H2S and then discharged as ultra-pure tail gas. After incineration, it meets the emission standards. In step (4): The H2S absorption step includes a step of using amine liquid as an absorbent; The hydrolysis catalyst includes an organic sulfur hydrolysis catalyst; It also includes the step of regenerating the amine-rich liquid obtained after absorbing H2S, and the step of returning the acid gas generated during regeneration to step (1) for combustion.

5. The sulfur recovery process for ultra-low sulfur emissions according to claim 4, characterized in that, In step (1): The combustion step is controlled at a temperature of 1100-1350℃; In the combustion step, the volume ratio of H2S and SO2 in the sulfur-producing tail gas is controlled to be 2:1; It also includes the step of condensing the obtained elemental sulfur to obtain liquid sulfur and separating it from the process gas; the condensation step temperature is 160-170℃.

6. The sulfur recovery process for ultra-low sulfur emissions according to claim 4 or 5, characterized in that, In step (2): The Claus catalytic conversion reaction includes a primary conversion reaction and a secondary conversion reaction; The catalyst loaded in the primary conversion reaction step includes a mixture of a sulfur recovery catalyst with oxygen removal function and a titanium dioxide-based sulfur recovery catalyst with high organic sulfur hydrolysis activity. The catalyst loaded in the secondary conversion reaction step includes an alumina-based sulfur production catalyst; The temperature of the first-stage conversion reaction is controlled at 230-250℃; The temperature of the secondary conversion reaction is controlled at 210-240℃; The space velocities of the first-order and / or second-order conversion reactions are controlled independently to be 400-800 h⁻¹. -1 .

7. The sulfur recovery process for ultra-low sulfur emissions according to claim 4 or 5, characterized in that, In step (3): The temperature of the hydrogenation reaction is controlled at 250-300℃; The catalyst loaded in the hydrogenation reaction step includes a multifunctional, highly active tail gas hydrogenation catalyst; It also includes the step of cooling the hydrogenated tail gas to 25-40°C.

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