Tail gas advanced treatment and sulfur recovery integrated process

Abstract

The invention relates to the technical field of coal chemical industry tail gas treatment and resource recovery, and discloses a tail gas advanced treatment and sulfur recovery integrated process which comprises the following steps: step 1, firstly, pretreating acidic tail gas generated by a coal chemical industry device; in the pretreatment process, liquid water and impurity particles in the tail gas need to be removed through a gas-liquid separation device, the gas-liquid separation device is of a cyclone separation and silk screen filtration combined structure, the inlet gas speed of a cyclone separation section is controlled to be 15-20 m / s, and the separation efficiency is larger than or equal to 95%. Impurities are removed through cyclone separation and silk screen filtration in the pretreatment stage, and catalyst blockage is avoided; in the integrated reaction system, a high-temperature thermal reaction unit ensures that the ammonia decomposition rate is greater than or equal to 99.9% and the hydrocarbon combustion rate is greater than or equal to 99.5%, and a two-stage low-temperature catalytic conversion unit is matched with ZnO-CuO modified activated carbon for deep adsorption, so that the tail gas SOemission concentration is less than or equal to 400mg / m and far exceeds the environmental protection standard; organic sulfur and inorganic sulfur are synergistically removed, and the treatment comprehensiveness is improved by 40% compared with that of a traditional process.

Description

Technical Field

[0001] This invention relates to the field of coal chemical tail gas treatment and resource recovery technology, specifically an integrated process for deep tail gas treatment and sulfur recovery. Background Technology

[0002] Traditional coal chemical acid tail gas treatment processes suffer from four major pain points, severely restricting environmental compliance and resource utilization, and failing to meet the needs of industrial production:

[0003] Incomplete sulfur removal and substandard emissions: Traditional processes often use a single Claus reaction, which cannot effectively treat organic sulfur (COS, CS2). The hydrolysis rate of organic sulfur is ≤80%, and the deep removal process is missing. The total sulfur content in the exhaust gas often exceeds 50mg / m³, and the SO2 emission concentration exceeds 800mg / m³, which does not meet the environmental protection standards (GB16297-1996) and faces the risk of environmental penalties.

[0004] Low resource recovery rate and serious waste: Sulfur recovery relies solely on simple condensation, and the H2S dissolved in liquid sulfur is not removed (content ≥50ppm), and the sulfur-containing waste gas generated during degassing is directly emitted, resulting in a total sulfur recovery rate ≤95% and serious waste of sulfur resources; at the same time, the waste heat of the tail gas is not effectively utilized, resulting in high energy consumption (unit treatment energy consumption ≥100kWh / ton of tail gas).

[0005] Poor process stability and high operation and maintenance costs: The catalyst has low activity (Claus reaction conversion rate ≤85%), is prone to blockage by impurities or deactivation due to overheating, and needs to be replaced frequently (replacement cycle ≤6 months); the equipment has poor corrosion resistance, and high-temperature exhaust gas and acidic media can easily cause equipment aging (service life ≤3 years), and operation and maintenance costs account for more than 30% of the total production cost.

[0006] Low level of automation and cumbersome operation: lack of real-time component analysis and closed-loop control, relying on manual adjustment of process parameters, which easily leads to problems such as gas-air ratio imbalance and temperature fluctuation, resulting in a decrease in reaction efficiency; and without an interlock protection system, failure to handle faults in a timely manner can easily lead to safety accidents (such as backfire and overpressure). Summary of the Invention

[0007] The purpose of this invention is to provide an integrated process for deep treatment of exhaust gas and sulfur recovery, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: an integrated process for deep treatment of exhaust gas and sulfur recovery, comprising the following steps:

[0009] Step 1: First, the acidic tail gas generated by the coal chemical plant is pretreated. This pretreatment process requires removing liquid water and impurity particles from the tail gas through a gas-liquid separation device. The gas-liquid separation device adopts a combination structure of cyclone separation and wire mesh filtration. The inlet gas velocity of the cyclone separation section is controlled at 15~20m / s, and the separation efficiency is ≥95%. The wire mesh filtration section uses 316L stainless steel wire mesh to ensure that the liquid water content of the tail gas after pretreatment is ≤0.1% (volume fraction) and the impurity particle content is ≤1mg / m³.

[0010] Step 2: Next, the pretreated exhaust gas is analyzed for its components. An online gas chromatograph is used to detect the concentrations of H2S, SO2, COS, CS2, CO2, and hydrocarbons in the exhaust gas in real time. The detection frequency is 1 time / minute, and the detection accuracy is ±0.1% (volume fraction). Based on the detection results, the total sulfur content and the proportion of organic sulfur in the exhaust gas are calculated. The formula for calculating the total sulfur content is:

[0011]

[0012] in The total sulfur content of the exhaust gas. , , , , These represent the volume concentrations of the corresponding components. The formula for calculating the percentage of organic sulfur is: (where is the molar mass of the sulfur compound in the hydrocarbon).

[0013]

[0014] The detection error for the organic sulfur content should be ≤2%;

[0015] Step 3: The system then enters the integrated reaction system, which includes a high-temperature thermal reaction unit, a low-temperature catalytic conversion unit, and a deep adsorption unit connected in series.

[0016] The high-temperature thermal reaction unit employs a lined combustion furnace with a corundum-mullite refractory brick lining, boasting a temperature resistance limit ≥1750℃. Preheated air (200-250℃) is introduced into the furnace, utilizing a waste heat recovery device with a preheating efficiency ≥80%. The molar ratio of H2S to O2 within the furnace is controlled at 2.8-3.2:1 by adjusting the air-to-gas ratio, ensuring that 1 / 3 of the H2S volume reacts according to the reaction formula. Oxidation to SO2, while simultaneously causing the ammonia in the tail gas to react according to the formula Complete decomposition, hydrocarbons according to the reaction formula Complete combustion is ensured, with the furnace outlet temperature controlled at 1250~1350℃, gas residence time ≥2 seconds, and ammonia decomposition rate ≥99.9% and hydrocarbon combustion rate ≥99.5%.

[0017] The multi-stage low-temperature catalytic conversion unit is equipped with two-stage catalytic reactors connected in series, specifically:

[0018] The primary catalytic reactor is packed with an organic sulfur hydrolysis-Claus bifunctional catalyst. This catalyst uses γ-Al₂O₃ as a support, loaded with 10%–15% (mass fraction) TiO₂ and 5%–8% (mass fraction) Co-Mo active components. The catalyst particle size is 3–5 mm, and the specific surface area is ≥200 m² / g. The inlet temperature of the primary reactor is controlled at 280–320 °C, the pressure at 0.12–0.15 MPa, and the space velocity at 800–1200 h⁻¹. -1 This causes COS in the exhaust gas to react according to the formula. Hydrolysis, CS2 according to the reaction formula Hydrolysis is performed to ensure that the hydrolysis rate of COS is ≥98% and the hydrolysis rate of CS2 is ≥95%, while the Claus reaction occurs simultaneously. ;

[0019] The secondary catalytic reactor is packed with a low-temperature, highly active Claus catalyst, using TiO2 as a support and loaded with 3%–5% (mass fraction) La2O3 as an auxiliary agent. The catalyst particle size is 2–4 mm, and the specific surface area is ≥150 m² / g. The inlet temperature of the secondary reactor is controlled at 220–240 °C, the pressure is the same as that of the primary reactor, and the space velocity is 1500–2000 h⁻¹. -1 This allows the remaining H2S to undergo a Claus reaction with SO2, achieving a conversion rate of ≥92%.

[0020] The deep adsorption unit uses ZnO-CuO modified activated carbon adsorbent with a particle size of 1~3mm, a pore volume ≥0.8cm³ / g, an adsorption temperature of 80~120℃, a pressure of 0.1~0.12MPa, and a space velocity of 500~800h⁻¹. -1 It deeply adsorbs residual H2S, SO2 and unhydrolyzed organic sulfur in the exhaust gas, ensuring that the total sulfur content of the exhaust gas after adsorption is ≤10mg / m³.

[0021] Step 4: The liquid sulfur generated by each unit is centrally treated. The process gas from the outlet of the high-temperature thermal reaction unit and the low-temperature catalytic conversion unit enters the shell-and-tube condenser. The process gas is introduced into the tube side and the demineralized water is introduced into the shell side. The outlet temperature of the process gas is controlled at 130~150℃ by adjusting the flow rate of the demineralized water. The liquid sulfur condensation rate is ≥99%. The condensed liquid sulfur enters the liquid sulfur degassing unit. Quinoline catalyst is added to the degassing unit. The liquid sulfur is circulated and sprayed by the liquid sulfur circulation pump. At the same time, nitrogen is introduced to purge and remove the H2S dissolved in the liquid sulfur to ≤5ppm. The sulfur-containing waste gas generated by degassing is returned to the high-temperature thermal reaction unit for reprocessing.

[0022] Step 5: The degassed liquid sulfur is solidified into columnar particles using a rotary drum molding machine. The molding machine speed is 5~8 r / min, the cooling water temperature is 20~30℃, and the particle moisture content is ≤0.1%. Finally, it is packaged into 50kg / bags using an automatic packaging machine with a packaging accuracy of ±0.5kg. The total sulfur recovery rate of the entire process is ≥99.9%, and the SO2 concentration in the tail gas emission is ≤400mg / m³.

[0023] Preferably, the gas-liquid separation device for acidic tail gas pretreatment specifically comprises:

[0024] The cyclone separation section adopts a tangential inlet structure, with an inlet pipe diameter to separation section diameter ratio of 0.2~0.3, a separation section length to diameter ratio of 3~4, and a cone section half-apex angle of 10°~15°. The flow field distribution is optimized through computational fluid dynamics (CFD) simulation, so that the airflow forms a stable vortex with a centrifugal force field strength ≥1000g in the separation section, which can efficiently separate liquid water droplets and impurity particles with a particle size ≥10μm.

[0025] The stainless steel wire mesh of the wire mesh filter section adopts a multi-layer folded structure with 5 to 8 layers and a wire mesh spacing of 5 to 10 mm. The uniform arrangement design ensures that the airflow velocity uniformity in the filter section is ≤ ±5%.

[0026] The online gas chromatograph for pretreated exhaust gas component analysis employs a dual-detector combination of a flame ionization detector (FID) and a thermal conductivity detector (TCD). The FID is used to detect hydrocarbons, while the TCD is used to detect H2S, SO2, COS, CS2, and CO2. The chromatographic columns used are a GDX-104 packed column and an SE-30 capillary column, with programmed temperature ramping.

[0027] The initial temperature was 40℃ and held for 5 minutes, then the temperature was increased to 200℃ at a rate of 10℃ / min and held for 10 minutes to ensure that the separation degree of each component was ≥1.5 and the single detection cycle was ≤5 minutes to meet the real-time control requirements.

[0028] To avoid corrosion of the chromatograph by high concentrations of H2S, a corrosion-resistant sampling probe made of Hastelloy C-276 is installed before the injection port. The sampling pipeline is made of polytetrafluoroethylene and heated to 120~150℃. The heating temperature is precisely controlled by a PID temperature controller, with temperature fluctuation ≤±2℃.

[0029] Meanwhile, online filters are installed on the sampling pipeline for regular automatic backflushing.

[0030] Preferably, in the high-temperature thermal reaction unit of the integrated reaction system, the combustion furnace lining adopts a double-layer structure, with the inner layer being corundum mullite refractory bricks and the outer layer being lightweight insulating bricks. An expansion joint with a width of 5-8mm is set between the two lining layers and filled with ceramic fiber cotton. The heat loss of the combustion furnace is ensured to be ≤5% through heat loss calculation.

[0031] The fuel gas for the combustion furnace preferentially uses hydrocarbons separated from the exhaust gas. The calorific value of the hydrocarbons is detected in real time using an online calorific value analyzer, and the theoretical air volume is calculated using the following formula:

[0032]

[0033] in The air volume is the theoretical air volume. This refers to fuel gas consumption. The excess air coefficient, Because the fuel gas has a low calorific value, the mixing ratio of the fuel gas and air is controlled by a proportional control valve;

[0034] The combustion furnace outlet temperature is cascaded controlled by "temperature - air volume / co-firing fuel gas". When the temperature is below 1250℃, the co-firing natural gas supply is automatically increased, as shown in the formula:

[0035]

[0036] in To increase the amount of natural gas used for combustion, This is the proportionality coefficient. Set the temperature for the outlet. This refers to the actual temperature at the outlet. This refers to the amount of exhaust gas treated.

[0037] When the temperature exceeds 1350℃, the air supply is automatically increased to dilute and cool the air, ensuring that the outlet temperature fluctuation is ≤±20℃.

[0038] An ultraviolet flame detector is installed inside the combustion furnace. When the flame is detected to be extinguished, the fuel gas supply is immediately cut off and nitrogen is introduced for purging to prevent backfire and explosion.

[0039] A quench section is installed at the outlet of the combustion furnace to rapidly reduce the process gas temperature from 1250~1350℃ to 300~350℃ by injecting demineralized water, thus preventing corrosion of downstream equipment by the high-temperature process gas. The demineralized water injection rate is calculated using the following formula:

[0040]

[0041] in For the amount of demineralized water used, For process gas mass flow rate, For the specific heat capacity of the process gas, This refers to the inlet temperature of the quench section. This refers to the outlet temperature of the quench section. The latent heat of vaporization of water, The specific heat capacity of water, This refers to the temperature of the demineralized water.

[0042] Preferably, in the first-stage catalytic reactor of the multi-stage low-temperature catalytic conversion unit, the preparation process of the organic sulfur hydrolysis-Claus bifunctional catalyst is as follows:

[0043] The γ-Al2O3 support was calcined at 500~600℃ for 2~3 hours to remove adsorbed water and impurities;

[0044] Subsequently, the calcined support was immersed in a mixed impregnation solution containing tetrabutyl titanate (TiO2 precursor), cobalt nitrate (Co precursor), and ammonium molybdate (Mo precursor) using an equal-volume impregnation method. The concentration of Ti in the impregnation solution was 0.5~1.0 mol / L, the concentration of Co was 0.1~0.2 mol / L, and the concentration of Mo was 0.2~0.3 mol / L. The impregnation temperature was 60~80℃, and the impregnation time was 4~6 hours.

[0045] After impregnation, dry at 120~150℃ for 4~6 hours, and then calcine at 500~550℃ for 3~4 hours to decompose the precursor into oxides and load them onto the surface of the carrier.

[0046] The prepared catalyst needs to be evaluated for activity under simulated exhaust gas conditions: 280℃, 0.1MPa, and 1000h. -1 At air velocity, COS hydrolysis rate ≥98%, CS2 hydrolysis rate ≥95%, and Claus reaction conversion rate ≥85% are required for the product to be put into use.

[0047] Preferably, in the secondary catalytic reactor of the multi-stage low-temperature catalytic conversion unit, the low-temperature high-activity Claus catalyst uses anatase TiO2 as a support, and the preparation process is as follows:

[0048] The TiO2 support was calcined at 450~500℃ for 1~2 hours;

[0049] The calcined carrier was immersed in an impregnation solution containing lanthanum nitrate (La2O3 precursor) using an excess impregnation method, and impregnated at room temperature for 8-12 hours.

[0050] Then dry at 100~120℃ for 8~10 hours, and then calcine at 550~600℃ for 2~3 hours;

[0051] The prepared catalyst had a particle size of 2-4 mm, a bulk density of 1.2-1.4 g / cm³, a BET specific surface area ≥150 m² / g, and a pore volume ≥0.5 cm³ / g, and was tested under simulated exhaust gas conditions at 220℃, 0.1 MPa, and for 2000 h⁻¹. -1 At space velocity, the conversion rate of the Claus reaction is ≥92%.

[0052] Preferably, the preparation process of the ZnO-CuO modified activated carbon adsorbent in the deep adsorption unit is as follows:

[0053] Coconut shell activated carbon was selected as raw material and activated with steam at 800~900℃. After activation, the specific surface area of ​​the activated carbon was ≥1000m² / g and the pore volume was ≥1.0cm³ / g.

[0054] The activated carbon was immersed in a mixed impregnation solution containing zinc nitrate (ZnO precursor) and copper nitrate (CuO precursor) using a co-impregnation method. The impregnation temperature was 50-60℃ and the impregnation time was 6-8 hours.

[0055] Then, it is dried at 120~150℃ for 6~8 hours, and then calcined at 300~350℃ for 2~3 hours to decompose the nitrate precursor into ZnO and CuO and uniformly loaded onto the surface of activated carbon.

[0056] The prepared adsorbent needs to be tested for adsorption performance under simulated exhaust gas conditions, and it can be put into use only if the adsorption breakthrough time is ≥100 hours.

[0057] Preferably, the liquid sulfur condenser adopts a shell-and-tube structure, with the tube bundle material being 316L stainless steel. It has 2-4 tube passes and a baffle plate structure in the shell side. By enhancing the turbulence in the shell side, the heat exchange efficiency is improved, and the overall heat transfer coefficient of the heat exchanger is ≥200W / (m²・℃). The process control of the condenser adopts a closed-loop regulation of "outlet temperature - demineralized water flow rate." The process gas temperature at the tube outlet is monitored in real time using a platinum resistance thermometer. When the temperature is higher than 150℃, the shell-side demineralized water flow rate is automatically increased; when the temperature is lower than 130℃, the demineralized water flow rate is automatically reduced, ensuring that the process gas outlet temperature remains stable at 130-150℃ with a temperature fluctuation ≤±3℃.

[0058] A differential pressure level gauge is installed on the shell side to control the liquid level at 100±20mm above the top of the heat exchange tube. When the liquid level is too high, the drain valve will automatically open to discharge excess demineralized water. When the liquid level is too low, the water supply valve will automatically open to replenish the demineralized water, preventing dry burning or a decrease in heat exchange efficiency.

[0059] The condensed liquid sulfur enters the sulfur sealing tank through a 316L stainless steel pipe with a steam jacket at the bottom. The sulfur sealing height of the sulfur sealing tank is calculated using the following formula:

[0060]

[0061] in This refers to the sulfur seal height. This refers to the process gas pressure at the outlet of the condenser cooler. The density of liquid sulfur, The acceleration due to gravity is 1.2, which is a safety factor to ensure reliable sulfur sealing without process gas leakage. The sulfur sealing tank is made of 316L stainless steel and is designed to have a volume of 1.5 to 2 times the hourly production of liquid sulfur. A breather valve is installed on the top of the tank to prevent excessively high or low pressure inside the tank from causing poor liquid sulfur delivery.

[0062] Preferably, the liquid sulfur degassing unit adopts a tower structure, and the tower is equipped with 3 to 5 layers of spiral nozzle spraying devices to ensure that the liquid sulfur is sprayed evenly to form a liquid film and prolong the contact time with nitrogen.

[0063] The quinoline catalyst used for degassing is 2,2'-diquinoline disulfide, which is continuously injected into the liquid sulfur pipeline at the top of the degassing tower through a metering pump. The amount of catalyst injected is calculated according to the formula for catalyst-liquid sulfur, where catalyst is the mass flow rate of catalyst and liquid sulfur is the mass flow rate of liquid sulfur.

[0064] The liquid sulfur circulation pump uses a magnetic drive pump, which enables the liquid sulfur to circulate 5 to 8 times in the degassing tower, thereby enhancing the H2S removal effect.

[0065] The nitrogen purging system uses nitrogen with a purity of ≥99.99%, which is evenly distributed at the bottom of the degassing tower through an annular porous tube distributor. The nitrogen flow rate is controlled by a mass flow meter to be 1 to 2 times the volume of liquid sulfur per hour to ensure that the nitrogen and liquid sulfur are in full contact. The H2S content in the liquid sulfur after degassing is ≤5ppm.

[0066] A wire mesh demister is installed at the top of the degassing tower to prevent liquid sulfur droplets from being carried out with sulfur-containing waste gas; the degassed liquid sulfur is transported to the forming unit by a liquid sulfur lift pump driven by magnetic force.

[0067] The drum of the rotary drum molding machine is made of 316L stainless steel. Cooling water is circulated inside the drum. By adjusting the drum speed and the cooling water flow rate, the solidification time of liquid sulfur on the drum surface is controlled to be 10~15 seconds. The strength of the molded particles is ≥50N and there is no breakage.

[0068] The automatic packaging machine uses a weighing method for packaging, and the packaged sulfur bags are transported to the steel structure sulfur storage shed via a conveyor belt.

[0069] This invention provides an integrated process for deep exhaust gas treatment and sulfur recovery. It offers the following advantages:

[0070] 1. This process removes impurities through cyclone separation and wire mesh filtration in the pretreatment stage to avoid catalyst clogging; in the integrated reaction system, the high-temperature thermal reaction unit ensures an ammonia decomposition rate of ≥99.9% and a hydrocarbon combustion rate of ≥99.5%, while the two-stage low-temperature catalytic conversion unit, combined with ZnO-CuO modified activated carbon for deep adsorption, results in an SO2 emission concentration of ≤400mg / m³ in the tail gas, far exceeding environmental standards; organic and inorganic sulfur are removed in a synergistic manner, improving the overall treatment effectiveness by 40% compared to traditional processes.

[0071] 2. In this process, the liquid sulfur generated in each unit is condensed and degassed, and then formed into columnar granules by a rotary drum. The granules are packaged as industrial-grade sulfur products in 50kg bags. The total sulfur recovery rate is ≥99.9%, which is 5 percentage points higher than that of traditional processes. The sulfur-containing waste gas generated during degassing is returned to the high-temperature reaction unit for recycling treatment, and the waste heat of the tail gas is used for air preheating. The unit processing energy consumption is reduced by 30%, achieving a win-win situation for environmental protection and economic benefits.

[0072] 3. This process uses a high-temperature combustion furnace with a corundum-mullite lining, resulting in a heat loss of ≤5%; the catalyst is a dual-functional, low-temperature, high-activity type with an activity cycle of ≥12 months, reducing the replacement frequency by 50%; the adsorbent is ZnO-CuO modified activated carbon, with a performance recovery rate of ≥95% after regeneration and a service life of ≥2 years; the equipment is mainly made of 316L stainless steel and Hastelloy, which improves corrosion resistance and extends the overall equipment life to more than 5 years.

[0073] 4. This process uses an online gas chromatograph to analyze the exhaust gas components in real time and uses PID closed-loop control to control the gas-air ratio and temperature; it is equipped with more than 10 interlock protections such as combustion furnace over-temperature and adsorption tower over-limit, and the fault handling is automated; the liquid sulfur degassing and molding process is fully mechanized, reducing manual intervention by 80% and operation and maintenance costs by 40%; at the same time, nitrogen, waste heat and other resources are recycled, further reducing operating costs. Attached Figure Description

[0074] Figure 1 This is the overall flow chart of the integrated process for deep exhaust gas treatment and sulfur recovery of the present invention;

[0075] Figure 2 This is a flowchart illustrating the preparation process of the key catalyst / adsorbent of this invention.

[0076] Figure 3 This invention relates to a safety interlock and material circulation diagram. Detailed Implementation

[0077] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0078] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0079] Example 1

[0080] A preferred embodiment of the integrated process for deep exhaust gas treatment and sulfur recovery provided by the present invention is as follows: Figure 1-3 As shown: An integrated process for deep exhaust gas treatment and sulfur recovery includes the following steps:

[0081] Step 1: First, the acidic tail gas generated by the coal chemical plant is pretreated. This pretreatment process requires removing liquid water and impurity particles from the tail gas through a gas-liquid separation device. The gas-liquid separation device adopts a combination structure of cyclone separation and wire mesh filtration. The inlet gas velocity of the cyclone separation section is controlled at 15~20m / s, and the separation efficiency is ≥95%. The wire mesh filtration section uses 316L stainless steel wire mesh to ensure that the liquid water content of the tail gas after pretreatment is ≤0.1% (volume fraction) and the impurity particle content is ≤1mg / m³.

[0082] Step 2: Next, the pretreated exhaust gas is analyzed for its components. An online gas chromatograph is used to detect the concentrations of H2S, SO2, COS, CS2, CO2, and hydrocarbons in the exhaust gas in real time. The detection frequency is 1 time / minute, and the detection accuracy is ±0.1% (volume fraction). Based on the detection results, the total sulfur content and the proportion of organic sulfur in the exhaust gas are calculated. The formula for calculating the total sulfur content is:

[0083]

[0084] in Total sulfur content in exhaust gas (unit: mg / m³). , , , , These are the volume concentrations (in %) of the corresponding components. The molar mass of sulfur compounds in hydrocarbons (unit: g / mol) is given by the formula for calculating the percentage of organic sulfur.

[0085]

[0086] The detection error for the organic sulfur content should be ≤2%;

[0087] Step 3: The system then enters the integrated reaction system, which includes a high-temperature thermal reaction unit, a low-temperature catalytic conversion unit, and a deep adsorption unit connected in series.

[0088] The high-temperature thermal reaction unit employs a lined combustion furnace with a corundum-mullite refractory brick lining, boasting a temperature resistance limit ≥1750℃. Preheated air (200-250℃) is introduced into the furnace, utilizing a waste heat recovery device with a preheating efficiency ≥80%. The molar ratio of H2S to O2 within the furnace is controlled at 2.8-3.2:1 by adjusting the air-to-gas ratio, ensuring that 1 / 3 of the H2S volume reacts according to the reaction formula. Oxidation to SO2, while simultaneously causing the ammonia in the tail gas to react according to the formula (Temperature ≥1250℃) Complete decomposition, hydrocarbons react according to the formula (Taking methane as an example) Complete combustion is required, with the furnace outlet temperature controlled at 1250~1350℃, gas residence time ≥2 seconds, ensuring ammonia decomposition rate ≥99.9% and hydrocarbon combustion rate ≥99.5%;

[0089] The multi-stage low-temperature catalytic conversion unit is equipped with two-stage catalytic reactors connected in series, specifically:

[0090] The primary catalytic reactor is packed with an organic sulfur hydrolysis-Claus bifunctional catalyst. This catalyst uses γ-Al₂O₃ as a support, loaded with 10%–15% (mass fraction) TiO₂ and 5%–8% (mass fraction) Co-Mo active components. The catalyst particle size is 3–5 mm, and the specific surface area is ≥200 m² / g. The inlet temperature of the primary reactor is controlled at 280–320℃, the pressure at 0.12–0.15 MPa (g), and the space velocity at 800–1200 h⁻¹. -1 This causes COS in the exhaust gas to react according to the formula. Hydrolysis, CS2 according to the reaction formula Hydrolysis is performed to ensure that the hydrolysis rate of COS is ≥98% and the hydrolysis rate of CS2 is ≥95%, while the Claus reaction occurs simultaneously. ;

[0091] The secondary catalytic reactor is packed with a low-temperature, highly active Claus catalyst, using TiO2 as a support and loaded with 3%–5% (mass fraction) La2O3 as an auxiliary agent. The catalyst particle size is 2–4 mm, and the specific surface area is ≥150 m² / g. The inlet temperature of the secondary reactor is controlled at 220–240 °C, the pressure is the same as that of the primary reactor, and the space velocity is 1500–2000 h⁻¹. -1 This allows the remaining H2S to undergo a Claus reaction with SO2, achieving a conversion rate of ≥92%.

[0092] The deep adsorption unit uses ZnO-CuO modified activated carbon adsorbent with a particle size of 1~3mm, a pore volume ≥0.8cm³ / g, an adsorption temperature of 80~120℃, a pressure of 0.1~0.12MPa(g), and a space velocity of 500~800h⁻¹. -1 It deeply adsorbs residual H2S, SO2 and unhydrolyzed organic sulfur in the exhaust gas, ensuring that the total sulfur content of the exhaust gas after adsorption is ≤10mg / m³.

[0093] Step 4: Centralized treatment of liquid sulfur generated from each unit. The process gas from the outlet of the high-temperature thermal reaction unit and the low-temperature catalytic conversion unit enters a shell-and-tube condenser. Process gas is introduced into the tube side, and demineralized water is introduced into the shell side. By adjusting the flow rate of the demineralized water, the outlet temperature of the process gas is controlled at 130~150℃ (the temperature range in which the viscosity of liquid sulfur is the lowest and the fluidity is the best). The liquid sulfur condensation rate is ≥99%. The condensed liquid sulfur enters the liquid sulfur degassing unit. Quinoline catalyst is added to the degassing unit (the amount added is 0.05%~0.1% of the mass of liquid sulfur). Liquid sulfur is circulated and sprayed through a liquid sulfur circulation pump (the circulation flow rate is 5~8 times the liquid sulfur production). At the same time, nitrogen is introduced for purging (the nitrogen flow rate is 1~2 times the volume of liquid sulfur / h) to remove H2S dissolved in the liquid sulfur to ≤5ppm. The sulfur-containing waste gas generated from degassing is returned to the high-temperature thermal reaction unit for reprocessing.

[0094] Step 5: The degassed liquid sulfur is solidified into columnar particles (2-3 mm in diameter and 5-8 mm in length) using a rotary drum molding machine. The molding machine speed is 5-8 r / min, the cooling water temperature is 20-30℃, and the particle moisture content is ≤0.1%. Finally, the particles are packaged in 50 kg / bags using an automatic packaging machine with a packaging accuracy of ±0.5 kg. The total sulfur recovery rate of the entire process is ≥99.9%, and the SO2 concentration in the exhaust gas is ≤400 mg / m³.

[0095] Example 2

[0096] Please see Figures 1-3 Furthermore, based on Example 1, the following is further obtained: In the gas-liquid separation device for acidic tail gas pretreatment, specifically:

[0097] The cyclone separation section adopts a tangential inlet structure, with an inlet pipe diameter to separation section diameter ratio of 0.2~0.3, a separation section length to diameter ratio of 3~4, and a cone section half-apex angle of 10°~15°. The flow field distribution is optimized through computational fluid dynamics (CFD) simulation, so that the airflow forms a stable vortex with a centrifugal force field strength ≥1000g (g is the acceleration due to gravity) in the separation section, which can efficiently separate liquid water droplets and impurity particles with a particle size ≥10μm.

[0098] The stainless steel wire mesh of the wire mesh filter section adopts a multi-layer folded structure with 5 to 8 layers and a wire mesh spacing of 5 to 10 mm. The uniform arrangement design ensures that the airflow velocity uniformity in the filter section is ≤ ±5%, avoiding excessive local flow velocity that could lead to wire mesh damage or reduced filtration efficiency.

[0099] The online gas chromatograph for pretreated tail gas component analysis employs a dual-detector combination of a flame ionization detector (FID) and a thermal conductivity detector (TCD). The FID is used to detect hydrocarbons (detection limit ≤ 0.01% (volume fraction)), and the TCD is used to detect H2S, SO2, COS, CS2, and CO2 (detection limit ≤ 0.005% (volume fraction)). The chromatographic columns used are a GDX-104 packed column (for separating H2S and COS) and an SE-30 capillary column (for separating SO2, CS2, and hydrocarbons). The column temperature is programmed.

[0100] The initial temperature was 40℃ and held for 5 minutes, then the temperature was increased to 200℃ at a rate of 10℃ / min and held for 10 minutes to ensure that the separation degree of each component was ≥1.5 and the single detection cycle was ≤5 minutes to meet the real-time control requirements.

[0101] To avoid corrosion of the chromatograph by high concentrations of H2S, a corrosion-resistant sampling probe made of Hastelloy C-276 is installed before the injection port. The sampling pipeline is made of polytetrafluoroethylene and heated to 120~150℃ (to prevent liquid sulfur from condensing and clogging). The heating temperature is precisely controlled by a PID temperature controller, with temperature fluctuations ≤±2℃.

[0102] Meanwhile, an online filter is installed on the sampling pipeline, and it is automatically backflushed regularly (the backflushing gas is nitrogen, the pressure is 0.4~0.6MPa, the backflushing time is 30 seconds / time, and the backflushing cycle is 1 hour) to prevent impurities from clogging the sampling pipeline and affecting the detection accuracy.

[0103] In the high-temperature thermal reaction unit of the integrated reaction system, the combustion furnace lining adopts a double-layer structure. The inner layer is corundum mullite refractory brick (thickness 200~250mm, bulk density ≥2.8g / cm³, room temperature compressive strength ≥80MPa, high temperature compressive strength ≥40MPa at 1400℃), and the outer layer is lightweight insulating brick (thickness 150~200mm, bulk density ≤1.0g / cm³, thermal conductivity ≤0.3W / (m・K) at 800℃). An expansion joint with a width of 5~8mm is set between the two inner layers and filled with ceramic fiber cotton (temperature resistance ≥1200℃). The heat loss of the combustion furnace is ensured to be ≤5% (based on the total heat release) through heat loss calculation.

[0104] The fuel gas for the combustion furnace preferentially uses hydrocarbons separated from the exhaust gas. The calorific value of the hydrocarbons is detected in real time using an online calorific value analyzer (detection range 3000~40000 kJ / m³, accuracy ±100 kJ / m³), and the theoretical air volume is calculated using the following formula:

[0105]

[0106] in Air refers to the theoretical air volume (unit: m³ / h). Fuel gas consumption (unit: kJ / h). The excess air coefficient (values ​​range from 1.05 to 1.1). The fuel gas has a low calorific value (unit: kJ / m³), and the mixing ratio of fuel gas and air is controlled by a proportional regulating valve to ensure complete combustion of the fuel gas (combustion efficiency ≥99.8%).

[0107] The combustion furnace outlet temperature is cascaded controlled by "temperature - air volume / co-firing fuel gas". When the temperature is below 1250℃, the supply of co-firing natural gas (purity ≥95% (volume fraction)) is automatically increased, according to the formula:

[0108]

[0109] in The amount of natural gas used for combustion (unit: m³ / h). It is a proportionality coefficient (0.001~0.002m³ / (h・℃・m³)). Set the outlet temperature (1250~1350℃). The actual outlet temperature (unit: °C). Exhaust gas treatment capacity (unit: m³ / h);

[0110] When the temperature exceeds 1350℃, the air supply is automatically increased to dilute and cool the air, ensuring that the outlet temperature fluctuation is ≤±20℃.

[0111] An ultraviolet flame detector (detection wavelength 200~300nm, response time ≤0.1 seconds) is installed in the combustion furnace. When the flame is detected to be extinguished, the fuel gas supply is immediately cut off and nitrogen is introduced for purging (purging time ≥5 minutes, nitrogen flow rate is 2~3 times the furnace volume / h) to prevent backfire and explosion.

[0112] A quench section is installed at the outlet of the combustion furnace to rapidly reduce the process gas temperature from 1250~1350℃ to 300~350℃ by injecting demineralized water, thus preventing corrosion of downstream equipment by the high-temperature process gas. The demineralized water injection rate is calculated using the following formula:

[0113]

[0114] in The amount of demineralized water used is expressed in kg / h. The mass flow rate of the process gas is expressed in kg / h. The specific heat capacity of the process gas (unit: kJ / (kg・℃), with a value of 1.2~1.4 kJ / (kg・℃)). The inlet temperature of the quench section (unit: °C). The outlet temperature of the quench section (unit: °C). The latent heat of vaporization of water (unit: kJ / kg, value is 2257 kJ / kg). This is the specific heat capacity of water (unit: kJ / (kg・℃), valued at 4.186 kJ / (kg・℃)). The temperature of the demineralized water is ℃ (value is 25~30℃).

[0115] The preparation process of the organic sulfur hydrolysis-Claus bifunctional catalyst in the first-stage catalytic reactor of the multi-stage low-temperature catalytic conversion unit is as follows:

[0116] The γ-Al2O3 support was calcined at 500~600℃ for 2~3 hours (heating rate 5℃ / min) to remove adsorbed water and impurities.

[0117] Subsequently, the calcined support was immersed in a mixed impregnation solution containing tetrabutyl titanate (TiO2 precursor), cobalt nitrate (Co precursor), and ammonium molybdate (Mo precursor) using an equal-volume impregnation method. The concentration of Ti in the impregnation solution was 0.5~1.0 mol / L, the concentration of Co was 0.1~0.2 mol / L, and the concentration of Mo was 0.2~0.3 mol / L. The impregnation temperature was 60~80℃, and the impregnation time was 4~6 hours.

[0118] After impregnation, dry at 120~150℃ for 4~6 hours, and then calcine at 500~550℃ for 3~4 hours (air flow rate 50~100mL / min) to decompose the precursor into oxides and load them onto the surface of the carrier.

[0119] The prepared catalyst needs to be prepared under simulated exhaust gas conditions ( 10% 0.5%, 0.2%, 5% Activity was evaluated under equilibrium conditions: 280℃, 0.1MPa, 1000h. -1 At air velocity, COS hydrolysis rate ≥98%, CS2 hydrolysis rate ≥95%, and Claus reaction conversion rate ≥85% are required for the product to be put into use.

[0120] The inlet temperature of the primary reactor is regulated by a combination of a process gas heat exchanger and a high-temperature mixing valve. The process gas heat exchanger is a shell-and-tube type. The tube side is supplied with the high-temperature process gas (300~340℃) from the outlet of the primary reactor, and the shell side is supplied with the low-temperature process gas (160~165℃) from the outlet of the secondary condenser. After heat exchange, the low-temperature process gas is heated to 220~240℃, and then mixed with a portion of the high-temperature process gas (1250~1350℃) from the outlet of the combustion furnace through the high-temperature mixing valve, so that the inlet temperature of the primary reactor is precisely controlled at 280~320℃ (temperature fluctuation ≤±5℃).

[0121] Three temperature detection points are set in the reactor bed (top 1 / 3, middle 2 / 3, and bottom) to monitor the temperature distribution in real time. When the hot spot temperature of the bed exceeds 350℃, the amount of low-temperature process gas mixing is automatically increased to prevent the catalyst from being deactivated due to overheating. In addition, a liquid sulfur collection tank is set at the bottom of the primary reactor. The tank body is made of 316L stainless steel and equipped with a steam jacket (heating temperature 130~150℃). The collected liquid sulfur is periodically transported to the liquid sulfur degassing unit by a liquid sulfur pump to avoid liquid sulfur depositing in the catalyst bed and clogging the micropores.

[0122] In the secondary catalytic reactor of the multi-stage low-temperature catalytic conversion unit, the low-temperature high-activity Claus catalyst uses anatase TiO2 as a support, and the preparation process is as follows:

[0123] The TiO2 support was calcined at 450-500℃ for 1-2 hours (heating rate 10℃ / min).

[0124] The calcined support was immersed in an impregnation solution containing lanthanum nitrate (La2O3 precursor) (La concentration 0.05~0.1mol / L) for 8~12 hours at room temperature using the excess impregnation method.

[0125] Then dry at 100~120℃ for 8~10 hours, and then calcine at 550~600℃ for 2~3 hours (nitrogen flow rate 30~50mL / min to prevent TiO2 crystal transformation).

[0126] The prepared catalyst had a particle size of 2-4 mm controlled by sieving, a bulk density of 1.2-1.4 g / cm³, a BET specific surface area ≥150 m² / g, and a pore volume ≥0.5 cm³ / g. Under simulated tail gas conditions (H₂S 2%, SO₂ 1%, H₂O 3%, N₂ equilibrium), at 220℃, 0.1 MPa, and for 2000 h… -1 At space velocity, the conversion rate of the Claus reaction is ≥92%;

[0127] The inlet temperature of the secondary reactor is precisely controlled by a process gas heat exchanger. The tube side of this heat exchanger receives the high-temperature process gas (300~340℃) from the outlet of the primary reactor, while the shell side receives the low-temperature process gas (160~165℃) from the outlet of the secondary condenser. By adjusting the heat exchanger's heat exchange area (tube length 4~6m, number of tube passes 2~4) and the gas flow rate, the inlet temperature of the secondary reactor is stabilized at 220~240℃ (temperature fluctuation ≤±3℃). An online H2S / SO2 analyzer using ultraviolet absorption is installed at the reactor outlet (detection range 0~5% (volume fraction), accuracy ±0. The amount of supplementary air at the inlet of the secondary reactor is adjusted according to the data feedback from the analyzer to maintain the molar ratio of H2S to SO2 in the outlet tail gas at 2:1±0.1, ensuring that the Claus reaction is in the optimal equilibrium state. At the same time, the secondary reactor is equipped with a differential pressure monitoring system (accuracy ±0.1kPa). When the bed pressure difference exceeds 5kPa, the catalyst regeneration program is automatically started (hot nitrogen gas (300~350℃) is introduced to purge for 4~6 hours, and the nitrogen flow rate is 3~5 times the reactor volume / h) to restore the catalyst activity and avoid the gas flow distribution being affected by excessively high pressure difference.

[0128] The preparation process of ZnO-CuO modified activated carbon adsorbent in the deep adsorption unit is as follows:

[0129] Coconut shell activated carbon was selected as raw material (particle size 1~3mm), and activated with steam at 800~900℃ (steam flow rate is 2~3 times the mass of activated carbon / h, activation time is 4~6 hours). After activation, the specific surface area of ​​the activated carbon is ≥1000m² / g and the pore volume is ≥1.0cm³ / g.

[0130] The activated carbon was immersed in a mixed impregnation solution containing zinc nitrate (ZnO precursor) and copper nitrate (CuO precursor) (Zn concentration 0.8~1.2 mol / L, Cu concentration 0.2~0.3 mol / L) using a co-impregnation method at a temperature of 50~60℃ for 6~8 hours.

[0131] Then, dry at 120~150℃ for 6~8 hours, and then calcine at 300~350℃ for 2~3 hours (argon flow rate 50~80mL / min to prevent metal oxide reduction) to decompose the nitrate precursor into ZnO and CuO and uniformly load them on the surface of activated carbon.

[0132] The prepared adsorbent needs to be tested under simulated exhaust gas conditions (H2S 500 mg / m³, SO2 200 mg / m³, COS 100 mg / m³, 100℃, 0.1 MPa, 800 h⁻¹). -1 Adsorption performance tests were conducted at a certain air velocity, and the adsorption breakthrough time was ≥100 hours (total sulfur content ≤10mg / m³ at breakthrough) before the product could be put into use.

[0133] The deep adsorption unit employs two fixed-bed adsorption towers operating alternately (one for adsorption and one for regeneration), with an adsorption cycle of 80-90 hours. The regeneration process utilizes hot nitrogen purging (nitrogen temperature 300-350℃, flow rate 1.5-2 times the tail gas treatment volume during adsorption, regeneration time 8-10 hours). After regeneration, the adsorption performance recovery rate of the adsorbent is ≥95%. The sulfur-containing waste gas generated during regeneration (1%-2% H2S, 0.5%-1% SO2) is returned to the high-temperature thermal reaction unit via pipeline, achieving sulfur recycling. The regenerated nitrogen is cooled (to 40-50℃) and dried (dew point). After being recycled at ≤-40℃, the recycling rate is ≥90%; a flame photometric detector (FPD) and an online total sulfur monitor (detection limit ≤1mg / m³) are installed at the outlet of the adsorption tower. When the total sulfur content at the outlet exceeds 10mg / m³, the tower automatically switches to the standby adsorption tower (switching time ≤30 seconds) and issues an alarm signal to ensure that the exhaust gas treatment continuously meets the standards; the shell of the adsorption tower is made of 316L stainless steel, with a design pressure of 0.3MPa (g) and a design temperature of 200℃, and is equipped with a pressure safety valve (opening pressure 0.25MPa (g)) to prevent overpressure damage to the equipment.

[0134] The liquid sulfur condenser adopts a shell-and-tube structure, with tube bundles made of 316L stainless steel (outer diameter 25~32mm, wall thickness 2~3mm, length 4~6m). It has 2~4 tube passes and a baffle plate structure in the shell side (baffle plate spacing 150~200mm, baffle plate cut-off ratio 25%~30%). By enhancing the turbulence in the shell side, heat transfer efficiency is improved, with an overall heat transfer coefficient ≥200W / (m²・℃). The condenser's process control employs a closed-loop regulation of "outlet temperature - demineralized water flow rate." A platinum resistance thermometer monitors the process gas temperature at the tube outlet in real time. When the temperature exceeds 150℃, the shell-side demineralized water flow rate is automatically increased; when the temperature falls below 130℃, the demineralized water flow rate is automatically reduced, ensuring the process gas outlet temperature remains stable between 130~150℃ (within this temperature range, liquid sulfur viscosity ≤200cP, optimal fluidity), and temperature fluctuations ≤±3℃.

[0135] A differential pressure level gauge is installed on the shell side to control the liquid level at 100±20mm above the top of the heat exchange tube. When the liquid level is too high, the drain valve will automatically open to discharge excess demineralized water. When the liquid level is too low, the water supply valve will automatically open to replenish the demineralized water, preventing dry burning or a decrease in heat exchange efficiency.

[0136] The condensed liquid sulfur enters the sulfur sealing tank through a 316L stainless steel pipe with a steam jacket at the bottom (jacket steam pressure 0.3~0.4MPa(g)). The sulfur sealing height of the sulfur sealing tank is calculated using the following formula:

[0137]

[0138] in The sulfur seal height (unit: m). The process gas pressure at the outlet of the condenser cooler (unit: Pa). The density of liquid sulfur is given in kg / m³ (value taken as 1800 kg / m³). The value is the acceleration due to gravity (unit: m / s², taken as 9.8 m / s²), and 1.2 is the safety factor to ensure reliable sulfur sealing without process gas leakage. The sulfur sealing tank is made of 316L stainless steel and is designed with a volume of 1.5 to 2 times the hourly production of liquid sulfur. A breather valve is installed on the top of the tank (opening pressure 0.02 MPa (g)) to prevent the liquid sulfur from being transported poorly due to excessively high or low pressure inside the tank.

[0139] The liquid sulfur degassing unit adopts a tower structure, with 3 to 5 layers of spiral nozzle spraying devices (atomization angle 90° to 120°, atomization particle size 500 to 800 μm) inside the tower to ensure that liquid sulfur is sprayed evenly to form a liquid film and prolong the contact time with nitrogen.

[0140] The quinoline catalyst used for degassing is 2,2'-diquinolinyl disulfide, which is continuously injected into the liquid sulfur pipeline at the top of the degassing tower through a metering pump. The amount of catalyst injected is calculated according to the formula for catalyst-liquid sulfur, where catalyst is the catalyst mass flow rate (unit: kg / h) and liquid sulfur is the liquid sulfur mass flow rate (unit: kg / h).

[0141] The liquid sulfur circulation pump uses a magnetic drive pump (material Hastelloy C-276, flow rate 50~100m³ / h, head 20~30m), which makes the circulation rate of liquid sulfur in the degassing tower reach 5~8 times, thus enhancing the H2S removal effect.

[0142] The nitrogen purging system uses nitrogen with a purity of ≥99.99%, which is evenly distributed at the bottom of the degassing tower through an annular porous tube distributor (pore diameter 2~3mm, pore spacing 50~100mm). The nitrogen flow rate is controlled by a mass flow meter to be 1~2 times the liquid sulfur volume / h to ensure that the nitrogen and liquid sulfur are in full contact. After degassing, the H2S content in the liquid sulfur is ≤5ppm.

[0143] A wire mesh demister is installed at the top of the degassing tower to prevent liquid sulfur droplets from being carried out with sulfur-containing waste gas; the degassed liquid sulfur is transported to the molding unit by a magnetically driven liquid sulfur lift pump (material Hastelloy C-276, flow rate 10~20m³ / h, head 30~40m).

[0144] The drum of the rotary drum molding machine is made of 316L stainless steel. Cooling water is circulated inside the drum (inlet water temperature ≤25℃, outlet water temperature ≤40℃). By adjusting the drum speed (5~8r / min) and the cooling water flow rate (10~20m³ / h), the solidification time of liquid sulfur on the drum surface is controlled to 10~15 seconds. The strength of the molded particles is ≥50N (tested by a particle strength tester), and there is no breakage.

[0145] The automatic packaging machine uses weighing packaging. The packaged sulfur bags are transported to the steel structure sulfur storage shed via conveyor belt (the storage shed has a ventilation rate of ≥10 times / h, a temperature of 0~40℃, and a relative humidity of ≤80%).

[0146] The entire process is equipped with a comprehensive safety interlock system, including a combustion furnace over-temperature interlock (emergency shutdown of fuel gas and introduction of nitrogen when temperature > 1400℃), a reactor over-pressure interlock (opening of emergency pressure relief valve when pressure > 0.2MPa(g), an adsorption tower outlet total sulfur exceeding standard interlock (switching to standby tower when total sulfur > 15mg / m³), a liquid sulfur pipeline over-temperature interlock (shutting off heating steam when temperature > 160℃), and a liquid sulfur pump tripping interlock (automatic start of standby pump). All interlocks have a response time of ≤ 1 second, ensuring safe and stable operation of the process. All sulfur-containing streams generated during the process are treated in a closed loop, with no sulfur loss and a stable total sulfur recovery rate of ≥ 99.9%.

[0147] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0148] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An integrated process for deep treatment of exhaust gas and sulfur recovery, characterized in that, Includes the following steps: Step 1: First, the acidic tail gas generated by the coal chemical plant is pretreated. This pretreatment process requires removing liquid water and impurity particles from the tail gas through a gas-liquid separation device. The gas-liquid separation device adopts a combination structure of cyclone separation and wire mesh filtration. The inlet gas velocity of the cyclone separation section is controlled at 15~20m / s, and the separation efficiency is ≥95%. The wire mesh filtration section uses 316L stainless steel wire mesh to ensure that the liquid water content of the tail gas after pretreatment is ≤0.1% (volume fraction) and the impurity particle content is ≤1mg / m³. Step 2: Next, the pretreated exhaust gas is analyzed for its components. An online gas chromatograph is used to detect the concentrations of H2S, SO2, COS, CS2, CO2, and hydrocarbons in the exhaust gas in real time. The detection frequency is 1 time / minute, and the detection accuracy is ±0.1% (volume fraction). Based on the detection results, the total sulfur content and the proportion of organic sulfur in the exhaust gas are calculated. The formula for calculating the total sulfur content is: in The total sulfur content of the exhaust gas. , , , , These represent the volume concentrations of the corresponding components. The formula for calculating the percentage of organic sulfur is: (where is the molar mass of the sulfur compound in the hydrocarbon). The detection error for the organic sulfur content should be ≤2%; Step 3: The process then proceeds to the integrated reaction system, which includes a high-temperature thermal reaction unit, a low-temperature catalytic conversion unit, and a deep adsorption unit connected in series. The high-temperature thermal reaction unit employs a lined combustion furnace with a corundum-mullite refractory brick lining, boasting a temperature resistance limit ≥1750℃. Preheated air (200-250℃) is introduced into the furnace, utilizing a waste heat recovery device with a preheating efficiency ≥80%. The molar ratio of H2S to O2 within the furnace is controlled at 2.8-3.2:1 by adjusting the air-to-gas ratio, ensuring that 1 / 3 of the H2S volume reacts according to the reaction formula. Oxidation to SO2, while simultaneously causing the ammonia in the tail gas to react according to the formula Complete decomposition, hydrocarbons according to the reaction formula Complete combustion is ensured, with the furnace outlet temperature controlled at 1250~1350℃, gas residence time ≥2 seconds, and ammonia decomposition rate ≥99.9% and hydrocarbon combustion rate ≥99.5%. The multi-stage low-temperature catalytic conversion unit is equipped with two-stage catalytic reactors connected in series, specifically: The primary catalytic reactor is packed with an organic sulfur hydrolysis-Claus bifunctional catalyst. This catalyst uses γ-Al₂O₃ as a support, loaded with 10%–15% (mass fraction) TiO₂ and 5%–8% (mass fraction) Co-Mo active components. The catalyst particle size is 3–5 mm, and the specific surface area is ≥200 m² / g. The inlet temperature of the primary reactor is controlled at 280–320 °C, the pressure at 0.12–0.15 MPa, and the space velocity at 800–1200 h⁻¹. -1 This causes COS in the exhaust gas to react according to the formula. Hydrolysis, CS2 according to the reaction formula Hydrolysis is performed to ensure that the hydrolysis rate of COS is ≥98% and the hydrolysis rate of CS2 is ≥95%, while the Claus reaction occurs simultaneously. ; The secondary catalytic reactor is packed with a low-temperature, highly active Claus catalyst, using TiO2 as a support and loaded with 3%–5% (mass fraction) La2O3 as an auxiliary agent. The catalyst particle size is 2–4 mm, and the specific surface area is ≥150 m² / g. The inlet temperature of the secondary reactor is controlled at 220–240 °C, the pressure is the same as that of the primary reactor, and the space velocity is 1500–2000 h⁻¹. -1 This allows the remaining H2S to undergo a Claus reaction with SO2, achieving a conversion rate of ≥92%. The deep adsorption unit uses ZnO-CuO modified activated carbon adsorbent with a particle size of 1~3mm, a pore volume ≥0.8cm³ / g, an adsorption temperature of 80~120℃, a pressure of 0.1~0.12MPa, and a space velocity of 500~800h⁻¹. -1 It deeply adsorbs residual H2S, SO2 and unhydrolyzed organic sulfur in the exhaust gas, ensuring that the total sulfur content of the exhaust gas after adsorption is ≤10mg / m³. Step 4: The liquid sulfur generated by each unit is centrally treated. The process gas from the outlet of the high-temperature thermal reaction unit and the low-temperature catalytic conversion unit enters the shell-and-tube condenser. The process gas is introduced into the tube side and the demineralized water is introduced into the shell side. The outlet temperature of the process gas is controlled at 130~150℃ by adjusting the flow rate of the demineralized water. The liquid sulfur condensation rate is ≥99%. The condensed liquid sulfur enters the liquid sulfur degassing unit. Quinoline catalyst is added to the degassing unit. The liquid sulfur is circulated and sprayed by the liquid sulfur circulation pump. At the same time, nitrogen is introduced to purge and remove the H2S dissolved in the liquid sulfur to ≤5ppm. The sulfur-containing waste gas generated by degassing is returned to the high-temperature thermal reaction unit for reprocessing. Step 5: The degassed liquid sulfur is solidified into columnar particles using a rotary drum molding machine. The molding machine speed is 5~8 r / min, the cooling water temperature is 20~30℃, and the particle moisture content is ≤0.1%. Finally, it is packaged into 50kg / bags using an automatic packaging machine with a packaging accuracy of ±0.5kg. The total sulfur recovery rate of the entire process is ≥99.9%, and the SO2 concentration in the tail gas emission is ≤400mg / m³.

2. The integrated process for deep treatment of exhaust gas and sulfur recovery according to claim 1, characterized in that: Specifically, the gas-liquid separation device for the acidic tail gas pretreatment includes: The cyclone separation section adopts a tangential inlet structure, with an inlet pipe diameter to separation section diameter ratio of 0.2~0.3, a separation section length to diameter ratio of 3~4, and a cone section half-apex angle of 10°~15°. The flow field distribution is optimized through computational fluid dynamics (CFD) simulation, so that the airflow forms a stable vortex with a centrifugal force field strength ≥1000g in the separation section, which can efficiently separate liquid water droplets and impurity particles with a particle size ≥10μm. The stainless steel wire mesh of the wire mesh filter section adopts a multi-layer folded structure with 5 to 8 layers and a wire mesh spacing of 5 to 10 mm. The uniform arrangement design ensures that the airflow velocity uniformity in the filter section is ≤ ±5%. The online gas chromatograph for pretreated exhaust gas component analysis employs a dual-detector combination of a flame ionization detector (FID) and a thermal conductivity detector (TCD). The FID is used to detect hydrocarbons, while the TCD is used to detect H2S, SO2, COS, CS2, and CO2. The chromatographic columns used are a GDX-104 packed column and an SE-30 capillary column, with programmed temperature ramping. The initial temperature was 40℃ and held for 5 minutes, then the temperature was increased to 200℃ at a rate of 10℃ / min and held for 10 minutes to ensure that the separation degree of each component was ≥1.5 and the single detection cycle was ≤5 minutes to meet the real-time control requirements. To avoid corrosion of the chromatograph by high concentrations of H2S, a corrosion-resistant sampling probe made of Hastelloy C-276 is installed before the injection port. The sampling pipeline is made of polytetrafluoroethylene and heated to 120~150℃. The heating temperature is precisely controlled by a PID temperature controller, with temperature fluctuation ≤±2℃. Meanwhile, online filters are installed on the sampling pipeline for regular automatic backflushing.

3. The integrated process for deep treatment of exhaust gas and sulfur recovery according to claim 1, characterized in that: In the high-temperature thermal reaction unit of the integrated reaction system, the combustion furnace lining adopts a double-layer structure. The inner layer is made of corundum mullite refractory bricks, and the outer layer is made of lightweight insulating bricks. An expansion joint with a width of 5-8mm is set between the two layers of lining and filled with ceramic fiber cotton. The heat loss of the combustion furnace is ensured to be ≤5% through heat loss calculation. The fuel gas for the combustion furnace preferentially uses hydrocarbons separated from the exhaust gas. The calorific value of the hydrocarbons is detected in real time using an online calorific value analyzer, and the theoretical air volume is calculated using the following formula: in The air volume is the theoretical air volume. This refers to fuel gas consumption. The excess air coefficient, Because the fuel gas has a low calorific value, the mixing ratio of the fuel gas and air is controlled by a proportional control valve; The combustion furnace outlet temperature is cascaded controlled by "temperature - air volume / co-firing fuel gas". When the temperature is below 1250℃, the co-firing natural gas supply is automatically increased, as shown in the formula: in To increase the amount of natural gas used for combustion, This is the proportionality coefficient. Set the temperature for the outlet. This refers to the actual temperature at the outlet. This refers to the amount of exhaust gas treated. When the temperature exceeds 1350℃, the air supply is automatically increased to dilute and cool the air, ensuring that the outlet temperature fluctuation is ≤±20℃. An ultraviolet flame detector is installed inside the combustion furnace. When the flame is detected to be extinguished, the fuel gas supply is immediately cut off and nitrogen is introduced for purging to prevent backfire and explosion. A quench section is installed at the outlet of the combustion furnace to rapidly reduce the process gas temperature from 1250~1350℃ to 300~350℃ by injecting demineralized water, thus preventing corrosion of downstream equipment by the high-temperature process gas. The demineralized water injection rate is calculated using the following formula: in For the amount of demineralized water used, For process gas mass flow rate, For the specific heat capacity of the process gas, This refers to the inlet temperature of the quench section. This refers to the outlet temperature of the quench section. The latent heat of vaporization of water, The specific heat capacity of water, This refers to the temperature of the demineralized water.

4. The integrated process for deep treatment of exhaust gas and sulfur recovery according to claim 1, characterized in that: The preparation process of the organic sulfur hydrolysis-Claus bifunctional catalyst in the first-stage catalytic reactor of the multi-stage low-temperature catalytic conversion unit is as follows: The γ-Al2O3 support was calcined at 500~600℃ for 2~3 hours to remove adsorbed water and impurities; Subsequently, the calcined support was immersed in a mixed impregnation solution containing tetrabutyl titanate (TiO2 precursor), cobalt nitrate (Co precursor), and ammonium molybdate (Mo precursor) using an equal-volume impregnation method. The concentration of Ti in the impregnation solution was 0.5~1.0 mol / L, the concentration of Co was 0.1~0.2 mol / L, and the concentration of Mo was 0.2~0.3 mol / L. The impregnation temperature was 60~80℃, and the impregnation time was 4~6 hours. After impregnation, dry at 120~150℃ for 4~6 hours, and then calcine at 500~550℃ for 3~4 hours to decompose the precursor into oxides and load them onto the surface of the carrier. The prepared catalyst needs to be evaluated for activity under simulated exhaust gas conditions: 280℃, 0.1MPa, and 1000h. -1 At air velocity, COS hydrolysis rate ≥98%, CS2 hydrolysis rate ≥95%, and Claus reaction conversion rate ≥85% are required for the product to be put into use.

5. The integrated process for deep treatment of exhaust gas and sulfur recovery according to claim 1, characterized in that: In the secondary catalytic reactor of the multi-stage low-temperature catalytic conversion unit, the low-temperature high-activity Claus catalyst uses anatase TiO2 as a support, and the preparation process is as follows: The TiO2 support was calcined at 450~500℃ for 1~2 hours; The calcined carrier was immersed in an impregnation solution containing lanthanum nitrate (La2O3 precursor) using an excess impregnation method, and impregnated at room temperature for 8-12 hours. Then dry at 100~120℃ for 8~10 hours, and then calcine at 550~600℃ for 2~3 hours; The prepared catalyst had a particle size of 2-4 mm, a bulk density of 1.2-1.4 g / cm³, a BET specific surface area ≥150 m² / g, and a pore volume ≥0.5 cm³ / g, and was tested under simulated exhaust gas conditions at 220℃, 0.1 MPa, and for 2000 h⁻¹. -1 At space velocity, the conversion rate of the Claus reaction is ≥92%.

6. The integrated process for deep treatment of exhaust gas and sulfur recovery according to claim 1, characterized in that: The preparation process of the ZnO-CuO modified activated carbon adsorbent in the deep adsorption unit is as follows: Coconut shell activated carbon was selected as raw material and activated with steam at 800~900℃. After activation, the specific surface area of ​​the activated carbon was ≥1000m² / g and the pore volume was ≥1.0cm³ / g. The activated carbon was immersed in a mixed impregnation solution containing zinc nitrate (ZnO precursor) and copper nitrate (CuO precursor) using a co-impregnation method. The impregnation temperature was 50-60℃ and the impregnation time was 6-8 hours. Then, it is dried at 120~150℃ for 6~8 hours, and then calcined at 300~350℃ for 2~3 hours to decompose the nitrate precursor into ZnO and CuO and uniformly loaded onto the surface of activated carbon. The prepared adsorbent needs to be tested for adsorption performance under simulated exhaust gas conditions, and it can be put into use only if the adsorption breakthrough time is ≥100 hours.

7. The integrated process for deep treatment of exhaust gas and sulfur recovery according to claim 1, characterized in that: The liquid sulfur condenser adopts a shell-and-tube structure with tube bundles made of 316L stainless steel. It has 2 to 4 tube passes and a baffle plate structure in the shell side. By enhancing the turbulence in the shell side, the heat exchange efficiency is improved. The overall heat transfer coefficient of the heat exchanger is ≥200W / (m²・℃). The process control of the condenser adopts a closed-loop regulation of "outlet temperature - demineralized water flow rate". The process gas temperature at the tube outlet is monitored in real time by a platinum resistance thermometer. When the temperature is higher than 150℃, the shell-side demineralized water flow rate is automatically increased. When the temperature is lower than 130℃, the demineralized water flow rate is automatically reduced to ensure that the process gas outlet temperature is stable at 130~150℃ with a temperature fluctuation of ≤±3℃. A differential pressure level gauge is installed on the shell side to control the liquid level at 100±20mm above the top of the heat exchange tube. When the liquid level is too high, the drain valve will automatically open to discharge excess demineralized water. When the liquid level is too low, the water supply valve will automatically open to replenish the demineralized water, preventing dry burning or a decrease in heat exchange efficiency. The condensed liquid sulfur enters the sulfur sealing tank through a 316L stainless steel pipe with a steam jacket at the bottom. The sulfur sealing height of the sulfur sealing tank is calculated using the following formula: in This refers to the sulfur seal height. This refers to the process gas pressure at the outlet of the condenser cooler. The density of liquid sulfur, The acceleration due to gravity is 1.2, and the safety factor is 1.2 to ensure reliable sulfur sealing without process gas leakage. The sulfur sealing tank is made of 316L stainless steel and is designed to have a volume of 1.5 to 2 times the hourly production of liquid sulfur. A breather valve is installed on the top of the tank to prevent excessively high or low pressure inside the tank from causing poor liquid sulfur transport.

8. The integrated process for deep treatment of exhaust gas and sulfur recovery according to claim 1, characterized in that: The liquid sulfur degassing unit adopts a tower structure, with 3 to 5 layers of spiral nozzle spraying devices inside the tower to ensure that liquid sulfur is sprayed evenly to form a liquid film and extend the contact time with nitrogen. The quinoline catalyst used for degassing is 2,2'-diquinoline disulfide, which is continuously injected into the liquid sulfur pipeline at the top of the degassing tower through a metering pump. The amount of catalyst injected is calculated according to the formula for catalyst-liquid sulfur, where catalyst is the mass flow rate of catalyst and liquid sulfur is the mass flow rate of liquid sulfur. The liquid sulfur circulation pump uses a magnetic drive pump, which enables the liquid sulfur to circulate 5 to 8 times in the degassing tower, thereby enhancing the H2S removal effect. The nitrogen purging system uses nitrogen with a purity of ≥99.99%, which is evenly distributed at the bottom of the degassing tower through an annular porous tube distributor. The nitrogen flow rate is controlled by a mass flow meter to be 1 to 2 times the volume of liquid sulfur per hour to ensure that the nitrogen and liquid sulfur are in full contact. The H2S content in the liquid sulfur after degassing is ≤5ppm. A wire mesh demister is installed at the top of the degassing tower to prevent liquid sulfur droplets from being carried out with sulfur-containing waste gas; the degassed liquid sulfur is transported to the forming unit by a liquid sulfur lift pump driven by magnetic force. The drum of the rotary drum molding machine is made of 316L stainless steel. Cooling water is circulated inside the drum. By adjusting the drum speed and the cooling water flow rate, the solidification time of liquid sulfur on the drum surface is controlled to be 10~15 seconds. The strength of the molded particles is ≥50N and there is no breakage. The automatic packaging machine uses a weighing method for packaging, and the packaged sulfur bags are transported to the steel structure sulfur storage shed via a conveyor belt.

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