A claus system for acid gas sulfur recovery

Abstract

The application discloses a kind of for acid gas sulfur recovery claus system, comprising: acid gas combustion subsystem, combustion advanced analysis control subsystem, conversion subsystem;Acid gas combustion subsystem includes sulfur-making combustion furnace;Combustion advanced analysis control subsystem is used to monitor the flow of acid gas, process tail gas and air in real time, monitor the concentration parameters of component in acid gas, process tail gas and the temperature parameters of sulfur-making combustion furnace burner, control the air flow entering burner, control the proportion of acid gas entering the burner, hearth and conversion subsystem of sulfur-making combustion furnace, so as to control the temperature of combustion furnace burner in preset range, and control the proportion of H2S and SO2 in the gas entering conversion subsystem reaches preset value 2:1;Conversion subsystem is used to generate elemental sulfur by low-temperature catalytic reaction to high-temperature process gas out of sulfur-making combustion furnace.This application improves the sulfur recovery rate by optimizing the technology of claus process itself, while matching reasonable tail gas treatment process, which will reduce the cost and production energy consumption of sulfur recovery unit to some extent, improve sulfur output.

Description

Technical Field

[0001] This invention belongs to the field of coal chemical industry, and specifically relates to a Claus process system for treating acidic gas containing hydrogen sulfide and producing sulfur as a byproduct. Background Technology

[0002] Coal chemical engineering is the process of using coal as raw material and chemically processing it into gaseous, liquid, and solid products or semi-finished products, which are then further processed into chemical and energy products. Raw coal contains sulfur, most of which is converted into sulfur-containing components such as H2S during processing and exists in a gaseous state. These H2S-containing gases are collectively referred to as acid gases. To protect the environment, H2S-containing acid gases are recovered and used as byproducts such as sulfur and sulfuric acid. The Claus process is the most widely used process in sulfur recovery units, and most sulfur recovery processes are developed based on the Claus process. The Claus process consists of a high-temperature sulfur production reaction in a sulfur-producing combustion furnace and low-temperature catalytic reactions in various converters. In the Claus process, acid gases are oxidized to SO2 by air (or oxygen-enriched air) in the sulfur-producing combustion furnace and undergo a high-temperature Claus reaction to produce elemental sulfur. The process gas then undergoes further low-temperature catalytic reactions in catalyst-filled converters to produce elemental sulfur.

[0003] Two-stage and three-stage Claus processes are collectively referred to as conventional Claus processes, which are widely used in sulfur recovery units. The difference lies in the number of converter stages; a two-stage Claus process uses a two-stage converter for low-temperature catalysis. Sulfur recovery rate is an important indicator for evaluating sulfur recovery units. The theoretical sulfur recovery rate for a two-stage Claus process is 90-95%, and for a three-stage Claus process, it is 95-98%. Due to limitations such as reaction thermodynamic equilibrium and the concentration of acidic gas (H2S), the sulfur recovery rate of sulfur production units using the conventional Claus process is lower than the theoretical value. For example, the actual recovery rate of the two-stage Claus process in coal chemical plants is 85-93%. Conventional Claus processes still leave some unrecovered sulfur; therefore, the sulfur production tail gas cannot be directly emitted and must undergo further desulfurization treatment by a tail gas treatment system before being discharged in compliance with standards.

[0004] Significant developments have been made in the conventional Claus process, primarily in two aspects: first, improvements to the Claus process itself to increase sulfur recovery rates, including the development of novel catalysts, lean acid gas sulfur production technologies, and oxygen-based sulfur recovery processes; and second, the development of suitable tail gas treatment processes. The optimization of both sulfur recovery and tail gas treatment processes aims to maximize sulfur recovery rates. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies in coal chemical plants, such as low concentration of acidic gas byproducts that fluctuates significantly due to coal quality, and the low actual sulfur recovery rate, large fluctuations in operating parameters, and high tail gas treatment costs associated with conventional Claus processes. To address the deficiencies of conventional Claus processes in coal chemical plants, and considering that direct discharge of process tail gases with certain calorific value, such as distillation tail gas and nitrogen washing tail gas, does not meet environmental regulations, this invention provides a Claus sulfur recovery system and method. This system offers advantages such as stable and reliable operation, high sulfur recovery rate, co-treatment of process tail gases, and low product energy consumption. It is suitable for treating acidic gases and process tail gases from various coal chemical plants and producing sulfur as a byproduct.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a Claus system for sulfur recovery from acidic gas, comprising: an acidic gas combustion subsystem, an advanced combustion analysis and control subsystem, and a conversion subsystem;

[0007] The acid gas combustion subsystem includes a sulfur production combustion furnace, which includes a furnace chamber and burners.

[0008] The advanced combustion analysis and control subsystem is used to monitor the flow rates of acid gas, process tail gas and air in real time, monitor the concentration parameters of components in acid gas and the temperature parameters of the sulfur production combustion furnace burner, control the air flow rate entering the burner, control the proportion of acid gas entering the sulfur production combustion furnace burner, furnace and conversion subsystem, thereby controlling the temperature of the combustion furnace burner within a preset range, and controlling the ratio of H2S and SO2 in the gas entering the conversion subsystem to reach a preset value of 2:1.

[0009] The advanced combustion analysis and control subsystem controls all acid gas to enter the burner of the sulfur-making combustion furnace for combustion with hot air, or controls the acid gas to be divided into three parts: one part enters the burner of the sulfur-making combustion furnace for combustion with hot air, the second part enters the furnace of the sulfur-making combustion furnace for a high-temperature Claus reaction, and the third part mixes with the high-temperature process gas exiting the sulfur-making combustion furnace and then enters the conversion subsystem.

[0010] The advanced combustion analysis and control subsystem controls all process exhaust gas to enter the burner of the sulfur production combustion furnace and burn with hot air.

[0011] The conversion subsystem is used to generate elemental sulfur from the high-temperature process gas exiting the sulfur combustion furnace through a low-temperature catalytic reaction.

[0012] Furthermore, the advanced combustion analysis and control subsystem controls the acid gas entering the burner of the sulfur-making combustion furnace to account for 40% to 100% of the total flow, the acid gas entering the sulfur-making combustion furnace to account for 0% to 60% of the total flow, and the acid gas entering the conversion subsystem of the sulfur-making combustion furnace to account for 0% to 20% of the total flow.

[0013] Furthermore, the advanced combustion analysis and control subsystem includes a flow and temperature measuring instrument, an online component analyzer, a comprehensive combustion analysis system, and a complex control system;

[0014] The flow and temperature measuring instrument is used to detect the flow rate and temperature of acid gas, process tail gas, air, and sulfur production tail gas discharged from the system.

[0015] The online component analyzer is installed on the acid gas pipeline and the process tail gas pipeline to detect the concentration of combustible components in the gas, and is installed on the sulfur production tail gas pipeline to detect the concentration of sulfur-containing components in the gas.

[0016] The combustion comprehensive analysis system is used to calculate the total amount of air required based on the acid gas flow rate and H2S / SO2 content, the process tail gas flow rate and composition, and adaptively control the actual air flow rate entering the burner by the H2S / SO2 content in the sulfur production tail gas.

[0017] The complex control system is used to control the temperature of the combustion furnace burner within a preset range by controlling the proportion of acid gas entering the sulfur production combustion furnace burner and furnace, and to control the air flow rate and the acid gas diversion flow rate to make the ratio of H2S and SO2 in the gas entering the conversion subsystem 2:1.

[0018] Furthermore, the acid gas is a gas containing H2S, and the process tail gas is tail gas with a certain calorific value emitted from external coal chemical plants.

[0019] Furthermore, the Claus system also includes a fire-tube waste heat boiler, which is located between the sulfur production combustion furnace and the conversion subsystem. The conversion subsystem includes a two- or three-stage Claus unit. Each Claus unit includes a set of sulfur condensers and a conversion system. The high-temperature process gas exiting the sulfur production combustion furnace enters the directly connected fire-tube waste heat boiler to produce medium-pressure steam and cool down. The process gas enters the first-stage sulfur condenser from the bottom tangential position of the waste heat boiler outlet pipe box. The process gas is cooled in the first-stage sulfur condenser, and liquid sulfur is condensed and separated from the process gas. The process gas after liquid sulfur separation enters the first-stage conversion system. The conversion subsystem also has a final-stage sulfur condenser in the last Claus unit.

[0020] Furthermore, each stage of the Claus unit also includes a heater and a distributor. The process gas exiting the sulfur condenser is preheated to a certain temperature by the heater and then evenly distributed by the distributor before entering the converter.

[0021] The distributor is in the form of a semi-circular tube. The diameter of the semi-circular tube is 0.3 to 1.0 times the diameter of the reactor inlet pipe, and the length is 0.3 to 0.8 times the diameter of the converter. Two identical semi-circular tubes are connected in parallel, and the connection point coincides with the center line of the inlet pipe. Distribution grooves or distribution holes are evenly distributed on the cylindrical surface. The area of ​​the grooves or holes is 0.8 to 1.5 times the cross-sectional area of ​​the inlet pipe.

[0022] Furthermore, the Claus system also includes a high-efficiency sulfur trap connected to the conversion subsystem. The process gas exiting the conversion subsystem enters the high-efficiency sulfur trap, which is equipped with high-efficiency separation internals to further recover liquid sulfur droplets in the process gas.

[0023] Furthermore, the Claus system also includes a superheating subsystem connected to a high-efficiency sulfur trap to further treat the sulfur production tail gas exiting the sulfur trap, superheating the tail gas to a certain temperature before sending it to the boiler system.

[0024] Furthermore, the burner temperature control range of the sulfur production combustion furnace is 950~1500℃; the furnace temperature control range of the sulfur production combustion furnace is 800~1200℃, and the pressure control range is 1.7~2.0 Bara.

[0025] Furthermore, the sulfur recovery rate of the Claus system is 92%~98%, and the total volume content of H2S and SO2 in the sulfur production tail gas is controlled within the range of 0.2%~1.0%.

[0026] The objective of this invention can be achieved through the following technical solutions:

[0027] a. An online analyzer for components such as H2S is installed on the acid gas pipeline. After preheating to a certain temperature, the acid gas is sent to the sulfur production combustion furnace. The preheated acid gas is divided into three parts. The first part enters the burner of the sulfur production combustion furnace and is burned with hot air. The flow rate of the raw material gas in this part should be as large as possible. The second part of the raw material gas enters the furnace of the sulfur production combustion furnace and undergoes a high-temperature Claus reaction. The third part is mixed with the high-temperature process gas exiting the sulfur production combustion furnace and then enters the conversion subsystem.

[0028] b. The process tail gas pipeline is equipped with an online analyzer for combustible components such as CO, H2, and CH4, and all of it is sent to the burner of the sulfur production combustion furnace for treatment.

[0029] c. The oxidizing medium for acidic gas combustion is air (or oxygen-enriched air), which originates from the blower air (or compressed air from outside the environment).

[0030] (Low-pressure oxygen); after the air is preheated to a certain temperature, it enters the burner of the sulfur production combustion furnace. Combustion strictly follows the ratio of H2S to SO2 of 2:1. The ratio of H2S to SO2 in the sulfur production combustion furnace is controlled by adjusting the air / acid gas ratio. The amount of air for combustion is controlled by main and secondary controls. The main control air flow accounts for about 70-90% of the total air, and the fine-tuning air flow accounts for about 10-30% of the total air. Controlling the H2S / SO2 ratio is the most important operating parameter of the sulfur recovery unit. The sulfur production combustion furnace is equipped with a dedicated combustion comprehensive analysis system. Based on the flow rate and component content of the raw material acid gas, the flow rate and component content of the process tail gas, and the flow rate and component content of the sulfur production tail gas, the correct total air volume is calculated and precise control is achieved through comprehensive control.

[0031] d. To improve the sulfur recovery rate of low-concentration acidic gas, process tail gases with certain calorific value emitted from coal chemical production units, such as distillation tail gas and nitrogen washing tail gas, are fully utilized for co-firing and heating. This can improve the sulfur recovery rate of the Claus unit and also address the pollution problem of direct emission of process tail gases into the atmosphere.

[0032] e. The high-temperature process gas from the sulfur combustion furnace enters the directly connected fire-tube waste heat boiler to produce medium-pressure steam and cool down. The process gas enters the first-stage sulfur condenser from the bottom tangential position of the waste heat boiler outlet pipe box. The process gas pipeline is gradually lowered and has a certain slope. Then the process gas is further cooled in the first-stage sulfur condenser, and liquid sulfur is condensed and separated from the process gas. The process gas after liquid sulfur separation enters the first-stage conversion system.

[0033] f. The process gas exiting the primary sulfur condenser is preheated to a certain temperature by the primary heater and then evenly distributed by the distributor before entering the primary converter. The catalyst in the primary converter adopts a mixed loading scheme, with a certain amount of oxygen leakage protection Claus catalyst in the upper layer and a certain amount of organic sulfur hydrolysis catalyst in the lower layer. The process gas exiting the primary converter first enters the primary heater to preheat the inlet process gas, and then enters the secondary sulfur condenser for further cooling. Liquid sulfur is condensed and separated from the process gas, and the process gas after liquid sulfur separation enters the secondary conversion system.

[0034] g. The process gas exiting the secondary sulfur condenser is heated to a certain temperature by the secondary heater and then evenly distributed by the distributor before entering the secondary converter, which is filled with a high-efficiency Claus catalyst. The process gas exiting the secondary converter enters the tertiary sulfur condenser for cooling, where liquid sulfur is condensed and separated from the process gas. The process gas after liquid sulfur separation enters the high-efficiency sulfur trap (or a tertiary conversion system, which adopts a tertiary Claus process and has the same process flow as the 2nd-stage conversion system).

[0035] h. To achieve a high sulfur recovery rate, the process gas outlet temperature of the final-stage sulfur condenser is relatively low, which can produce low-pressure steam as a byproduct. This steam is cooled by an air cooler and then used as boiler water for recycling. The process gas exiting the final-stage sulfur condenser enters a high-efficiency sulfur trap. The sulfur trap is equipped with high-efficiency separation internals to further recover liquid sulfur droplets from the process gas.

[0036] i. Liquid sulfur separated by each stage of the sulfur condenser flows by gravity into the liquid sulfur pool after being sealed by a liquid sulfur seal. Hot air is used for liquid sulfur degassing. The tail gas from the liquid sulfur pool is drawn and pressurized by a steam ejector and then sent to the sulfur production combustion furnace for further treatment and recovery. The tail gas from the sulfur production process exiting the sulfur collector requires further treatment. To reduce the investment and cost of tail gas treatment, the boiler system of the coal chemical plant is used to co-process the tail gas. To avoid problems such as liquid sulfur solidification, the tail gas is first superheated to a certain temperature before being sent to the boiler system.

[0037] The feed gas described in this invention is H2S-rich acidic gas produced as a byproduct of the desulfurization system of a coal chemical plant, wherein the molar content of H2S is 20%~50%, the molar content of (N2+CO2) is 30%~70%, the methanol content is 0.1~1%, the acidic gas temperature is 20~40℃, and the acidic gas pressure is 1.8~3.0 Bara.

[0038] The process tail gas is the tail gas with a certain calorific value emitted by the coal chemical plant. The molar content of H2S is 1%~5%, the content of combustible components such as hydrocarbons, CH4, CO, and H2 is 1%~40%, and the remainder is inert components such as N2 and AR. The tail gas temperature is 20~100℃ and the tail gas pressure is 2~10 Bara.

[0039] The acidic gas entering the sulfur recovery system is preheated to 150~220℃ and then divided into three parts. The first part enters the burner of the sulfur production combustion furnace and is burned with hot air, with a flow rate ratio of 40~100%. The second part of the acidic gas enters the furnace of the sulfur production combustion furnace, with a flow rate ratio of 0~40%. The third part of the acidic gas mixes with the high-temperature process gas exiting the sulfur production combustion furnace and then enters the conversion subsystem, with a flow rate ratio of 0~20%.

[0040] The sulfur production combustion furnace is equipped with high-efficiency, low-NOx burners, which can maintain stable combustion of acidic gas, with a temperature control range of 950~1500 ℃; the furnace temperature control range of the sulfur production combustion furnace is 800~1200℃, and the pressure control range is 1.7~2.0 Bara.

[0041] The sulfur production combustion furnace is equipped with a direct-connected fire-tube waste heat boiler to produce medium-pressure steam with a steam pressure range of 2.0~6.0 MPaG and a process gas temperature control range of 260~340℃ at the outlet of the waste heat boiler.

[0042] Each stage of the converter is equipped with a distributor to uniformly distribute the airflow. The temperature control range for process gas entering the first-stage converter is 225~245 ℃, and the catalyst bed temperature is 260~340 ℃; the temperature control range for process gas entering the second-stage converter is 205~230 ℃, and the bed hot spot temperature is 230~300 ℃; the temperature control range for process gas entering the third-stage converter is 195~220 ℃, and the bed hot spot temperature is 210~240 ℃.

[0043] The Claus process achieves a sulfur recovery rate of approximately 92-98%, with the (H2S+SO2) content in the sulfur production tail gas controlled within the range of 0.2-1.0%, and the heating temperature of the sulfur production tail gas controlled within the range of 160-240℃.

[0044] The sulfur production tail gas treatment process employs a boiler system for collaborative processing.

[0045] The process gas is cooled and liquid sulfur is separated by sulfur condensers at each stage. The outlet temperature is controlled within the range of 150~200℃, and the pressure of the by-product steam from each stage of sulfur condensers is controlled within the range of 0.4~0.8MPaG.

[0046] The process gas is cooled by the final stage sulfur condenser, with the outlet temperature controlled within the range of 125~140℃; the pressure of the by-product steam from the third stage sulfur condenser is controlled within the range of 0.1~0.2MPaG; the steam of this grade is cooled into condensate by the air cooler and used as boiler water for circulation.

[0047] The tail gas from the liquid sulfur pool is drawn and pressurized by a steam injector and then sent to the furnace of the sulfur production combustion furnace for recovery and treatment. The furnace is equipped with a specially structured pipe for treating the tail gas.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] (1) The sulfur production combustion furnace can achieve a higher combustion temperature through technical measures such as acid gas / air preheating and process tail gas co-firing, which can maintain stable combustion and obtain a higher sulfur recovery rate.

[0050] (2) Appropriately increasing the operating pressure of the sulfur production combustion furnace is beneficial to the high-temperature Claus reaction and can increase the yield.

[0051] (3) The sulfur combustion furnace is equipped with a direct-connected fire-tube waste heat boiler that produces medium-pressure steam as a byproduct. The outlet temperature is high and there is no liquid sulfur condensation. Therefore, the temperature difference of the waste heat boiler is low, and the service life of the waste heat boiler is long. The process gas outlet of the waste heat boiler is located at the bottom tangent position of the outlet pipe box, and it slopes to the inlet of the first-stage sulfur condenser through the step-by-step low pipeline, so there is no liquid sulfur accumulation.

[0052] (4) Each stage of the converter is equipped with a new type of gas distributor, the process gas flow is uniform, the catalyst bed is basically free of flow deviation, and the reaction efficiency is high.

[0053] (5) The secondary and tertiary converters (if any) are all filled with high-efficiency, low-temperature Claus catalysts, which can increase the driving force of the Claus reaction and improve the sulfur recovery rate.

[0054] (6) The sulfur production combustion furnace is equipped with a comprehensive analysis system for combustion air distribution, which accurately calculates the air distribution volume and strictly controls the tail gas H2S / SO2 ratio to 2:1, thereby improving the sulfur recovery rate of each stage of the converter.

[0055] (7) The high-efficiency sulfur trap adopts high-efficiency separation internals, with high liquid sulfur separation efficiency and less liquid sulfur droplet escape.

[0056] (8) The sulfur production tail gas is heated and then sent to the boiler system for co-processing, eliminating the tail gas incinerator, saving combustion gas consumption, and reducing the operating cost of the sulfur recovery unit.

[0057] (9) The tail gas from the liquid sulfur pool is pressurized and sent to the furnace of the sulfur combustion furnace for treatment, which can avoid the environmental problems of direct emission and improve the total sulfur recovery rate.

[0058] (10) The hot air used for degassing the liquid sulfur pool comes from the air cooler of the final stage sulfur condenser, making full use of the heat of the low-grade steam and reducing the energy consumption of the device. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the Claus system used for sulfur recovery from acidic gas in an embodiment.

[0060] Figure reference numerals: 101-Online analyzer of acid gas components; 102-Acid gas heater; 103-Blower; 104-Comprehensive analysis system for sulfur production / combustion; 105-Air heater; 106-Burnhead of sulfur production combustion furnace; 107-Sulfur production combustion furnace; 108-Waste heat boiler; 109-First-stage sulfur condenser; 110-First-stage heater; 111-First-stage converter; 112-Second-stage sulfur condenser; 113-Second-stage heater; 114-Second-stage converter; 115-Third-stage sulfur condenser; 116-High-efficiency sulfur trap; 117-Tail gas heater; 118-Boiler system; 119-Air cooler; 120~123-Liquid sulfur seal; 124-Liquid sulfur pool; 125-Liquid sulfur pump; 126-Steam ejector; 127-Online analyzer of sulfur production tail gas components; 128-Online analyzer of combustible components in process tail gas.

[0061] Figure 2 This is a schematic diagram of the distributor in the embodiment. Detailed Implementation

[0062] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort should fall within the scope of protection of the present application.

[0063] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product or device.

[0064] Taking the acidic gas from the low-temperature methanol washing byproduct and the process tail gas from the liquid nitrogen washing byproduct of a coal chemical plant as examples, the acidic gas has a temperature of 35 ℃, a pressure of 2 BarA, and a molar flow rate of 100 kmol / h. The molar composition is shown in Table 1 below.

[0065] Table 1

[0066] Components <![CDATA[H2]]> COS <![CDATA[CO2]]> <![CDATA[H2S]]> <![CDATA[N2]]> <![CDATA[CH3OH]]> molar content / % 0.0001 1.25 60.0177 30.0248 8.5884 0.1189

[0067] The process exhaust gas temperature is 30 ℃, the pressure is 3.5 BarA, and the molar flow rate is 10 kmol / h. The molar composition is shown in Table 2 below.

[0068] Table 2

[0069] Components <![CDATA[H2]]> CO <![CDATA[CH4]]> <![CDATA[N2]]> Ar molar content / % 5 15 0.5 79 0.5

[0070] The H2S+COS molar content of the aforementioned acidic gas is 31.2748%, classifying it as a low-concentration acidic gas. An online component analyzer 101 is installed on the acidic gas pipeline entering the sulfur recovery unit to analyze the content of combustible components such as H2S+COS, H2, and CH3OH in the acidic gas in real time. A component analyzer 128 is installed on the process tail gas pipeline to analyze the content of combustible components such as CO, H2, and CH4 in the acidic gas in real time. The analysis data, along with the acidic gas and process tail gas flow rates, are analyzed and calculated by the sulfur production / combustion integrated analysis system 104 to obtain the theoretical air distribution volume. Afterwards, all the process tail gas enters the sulfur-making combustion furnace burner 106. The acid gas, preheated to 210°C by heater 102, is divided into three parts. The first part, accounting for approximately 70% of the total gas volume, enters the sulfur-making combustion furnace burner 106 and is combusted with a certain proportion of hot air. The second part, accounting for approximately 20% of the total gas volume, enters the sulfur-making combustion furnace furnace 107 to undergo a high-temperature Claus reaction. The furnace temperature is approximately 890°C. The hot air for combustion is introduced from external compressed air or a blower. The air flow requirement calculated by the sulfur-making / combustion integrated analysis system 104 is approximately 74 kmol / h. After being heated to 210°C by heater 105, the air enters the sulfur-making combustion furnace burner 106 through the main pipeline (80% gas volume, main control) and branch pipelines (20% gas volume, auxiliary control). The sulfur-making tail gas pipeline at the unit outlet is equipped with an online component analyzer. The analysis data is analyzed and calculated by the sulfur-making / combustion integrated analysis system 104, and the air flow of the branch pipeline is adaptively adjusted based on feedback. The high-temperature process gas from the sulfur combustion furnace 106 first enters the waste heat boiler 108 to produce 4.0 MPaG steam, and the temperature drops to 320℃.

[0071] The process gas then enters the primary sulfur condenser 109, producing 0.6 MPaG steam as a byproduct, with the temperature dropping to 180°C. Simultaneously, liquid sulfur is condensed and separated from the process gas. The process gas is then mixed with the remaining acidic gas from the third section and heated to 240°C by the primary heater 110 before entering the primary converter 111. Under the catalysis of different catalysts, the Claus reaction and organic sulfur hydrolysis reactions occur respectively. The process gas is then first heated by the primary heater 110 and then sent to the secondary sulfur condenser 112, producing 0.6 MPaG steam as a byproduct, with the temperature dropping to 170°C. Simultaneously, liquid sulfur is condensed and separated from the process gas. The process gas is then heated to 210°C by the secondary heater 113 before entering the secondary converter 114, where the Claus reaction for sulfur production occurs under the catalysis of a highly efficient catalyst. The process gas then enters the three-stage sulfur condenser 115, producing 0.1 MPaG steam as a byproduct. This steam is condensed by the air cooler 119 and reused as boiler water. The process gas temperature drops to 130°C, and liquid sulfur is simultaneously condensed and separated from the process gas. The process gas then enters the high-efficiency sulfur trap 116 to recover residual liquid sulfur droplets. The gas after separating the liquid sulfur droplets is the sulfur production tail gas. The sulfur production tail gas is heated to 200°C by the tail gas heater 117 and sent to the boiler system 118 for co-treatment and emission compliance.

[0072] Liquid sulfur separated and recovered by sulfur condensers and high-efficiency sulfur traps at each stage enters the liquid sulfur pool through liquid sulfur seals 120-123. The liquid sulfur degassing medium is hot air from the outlet of air cooler 119. The tail gas from the liquid sulfur pool is pressurized to 2 BarA by steam ejector 126 and sent to the furnace 107 of the sulfur production combustion furnace for combustion treatment.

[0073] The temperature of the sulfur production tail gas was 200 ℃, the pressure was 1.2 BarA, the molar flow rate was 157 kmol / h, the (H2S+SO2) content was 0.771%, and the sulfur recovery rate was 95.2%.

[0074] The system and method described in this invention can improve sulfur recovery by about 2% compared with the conventional two-stage Claus process, which has significant beneficial effects and can be used to produce recovered sulfur.

[0075] The above embodiment is used to produce sulfur. With a slight modification to this embodiment, adding a three-stage converter, it can be used to replace the conventional three-stage Claus process for sulfur production.

[0076] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A Claus system for recovering sulfur from acidic gas, characterized in that... include: Acid gas combustion subsystem, advanced combustion analysis and control subsystem, conversion subsystem; The acid gas combustion subsystem includes a sulfur production combustion furnace, which includes a furnace chamber and burners. The advanced combustion analysis and control subsystem is used to monitor the flow rates of acid gas, process tail gas and air in real time, monitor the concentration parameters of components in acid gas and the temperature parameters of the sulfur production combustion furnace burner, control the air flow rate entering the burner, control the proportion of acid gas entering the sulfur production combustion furnace burner, furnace and conversion subsystem, thereby controlling the temperature of the combustion furnace burner within a preset range, and controlling the ratio of H2S and SO2 in the gas entering the conversion subsystem to reach a preset value of 2:

1. The advanced combustion analysis and control subsystem controls the acid gas to be divided into three parts. One part enters the burner of the sulfur production combustion furnace and is burned with hot air. The second part enters the furnace of the sulfur production combustion furnace and undergoes a high-temperature Claus reaction. The third part is mixed with the high-temperature process gas exiting the sulfur production combustion furnace and then enters the conversion subsystem. The advanced combustion analysis and control subsystem controls all process exhaust gas to enter the burner of the sulfur production combustion furnace and burn with hot air. The conversion subsystem is used to generate elemental sulfur from the high-temperature process gas exiting the sulfur combustion furnace through a low-temperature catalytic reaction. The advanced combustion analysis and control subsystem controls the acid gas entering the burner of the sulfur-making combustion furnace to account for 40% to 100% of the total flow, the acid gas entering the sulfur-making combustion furnace to account for 0% to 60% of the total flow and not zero, and the acid gas entering the conversion subsystem of the sulfur-making combustion furnace to account for 0% to 20% of the total flow and not zero. The acidic gas is a gas containing H2S, and the process tail gas is tail gas with a certain calorific value emitted from an external coal chemical plant. The burner temperature of the sulfur-producing combustion furnace is controlled within the range of 950~1500℃; the furnace temperature is controlled within the range of 800~1200℃, and the pressure is controlled within the range of 1.7~2.0 Bara.

2. The Claus system for sulfur recovery from acidic gas according to claim 1, characterized in that: The advanced combustion analysis and control subsystem includes a flow and temperature measuring instrument, an online component analyzer, a comprehensive combustion analysis system, and a complex control system; The flow and temperature measuring instrument is used to detect the flow rate and temperature of acid gas, process tail gas, air, and sulfur production tail gas discharged from the system. The online component analyzer is installed on the acid gas pipeline and the process tail gas pipeline to detect the concentration of combustible components in the gas, and is installed on the sulfur production tail gas pipeline to detect the concentration of sulfur-containing components in the gas. The combustion comprehensive analysis system is used to calculate the total amount of air required based on the acid gas flow rate and H2S / SO2 content, the process tail gas flow rate and composition, and adaptively control the actual air flow rate entering the burner by the H2S / SO2 content in the sulfur production tail gas. The complex control system is used to control the temperature of the combustion furnace burner within a preset range by controlling the proportion of acid gas entering the sulfur production combustion furnace burner and furnace, and to control the air flow rate and the acid gas diversion flow rate to make the ratio of H2S and SO2 in the gas entering the conversion subsystem 2:

1.

3. The Claus system for sulfur recovery from acidic gas according to claim 1, characterized in that: The Claus system also includes a fire-tube waste heat boiler, which is located between the sulfur production combustion furnace and the conversion subsystem. The conversion subsystem includes a two- or three-stage Claus unit. Each Claus unit includes a set of sulfur condensers and a conversion system. The high-temperature process gas from the sulfur production combustion furnace enters the directly connected fire-tube waste heat boiler to produce medium-pressure steam and cool down. The process gas enters the first-stage sulfur condenser from the bottom tangential position of the waste heat boiler outlet pipe box. The process gas is cooled in the first-stage sulfur condenser, and liquid sulfur is condensed and separated from the process gas. The process gas after liquid sulfur separation enters the first-stage conversion system. The conversion subsystem also has a final-stage sulfur condenser in the last Claus unit.

4. The Claus system for sulfur recovery from acidic gas according to claim 3, characterized in that: Each Claus unit also includes a heater and a distributor. The process gas from the sulfur outlet condenser is preheated to a certain temperature by the heater and then evenly distributed by the distributor before entering the converter. The distributor is in the form of a semi-circular tube. The diameter of the semi-circular tube is 0.3 to 1.0 times the diameter of the reactor inlet pipe, and the length is 0.3 to 0.8 times the diameter of the converter. Two identical semi-circular tubes are connected in parallel, and the connection point coincides with the center line of the inlet pipe. Distribution grooves or distribution holes are evenly distributed on the cylindrical surface. The area of ​​the grooves or holes is 0.8 to 1.5 times the cross-sectional area of ​​the inlet pipe.

5. The Claus system for sulfur recovery from acidic gas according to claim 1, characterized in that: The Claus system also includes a high-efficiency sulfur trap, which is connected to the conversion subsystem. The process gas exiting the conversion subsystem enters the high-efficiency sulfur trap, which is equipped with high-efficiency separation internals to further recover liquid sulfur droplets in the process gas.

6. The Claus system for sulfur recovery from acidic gas according to claim 5, characterized in that: The Claus system also includes a superheating subsystem, which is connected to a high-efficiency sulfur trap to further treat the sulfur production tail gas exiting the sulfur trap. The sulfur production tail gas is superheated to a certain temperature and then sent to the boiler system.

7. The Claus system for sulfur recovery from acidic gas according to claim 1, characterized in that: The sulfur recovery rate of the Claus system is 92%~98%, and the total volume content of H2S and SO2 in the sulfur production tail gas is controlled within the range of 0.2%~1.0%.

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