CN109133012B - Sulfur recovery process for high-concentration acid gas - Google Patents
Sulfur recovery process for high-concentration acid gas Download PDFInfo
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- CN109133012B CN109133012B CN201811006482.6A CN201811006482A CN109133012B CN 109133012 B CN109133012 B CN 109133012B CN 201811006482 A CN201811006482 A CN 201811006482A CN 109133012 B CN109133012 B CN 109133012B
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- C01B17/00—Sulfur; Compounds thereof
- C01B17/02—Preparation of sulfur; Purification
- C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
- C01B17/0404—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process
- C01B17/0426—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process characterised by the catalytic conversion
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- C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
- C01B17/0473—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by reaction of sulfur dioxide or sulfur trioxide containing gases with reducing agents other than hydrogen sulfide
- C01B17/0491—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by reaction of sulfur dioxide or sulfur trioxide containing gases with reducing agents other than hydrogen sulfide with hydrogen or hydrogen-containing mixtures, e.g. synthesis gas
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Abstract
The invention provides a sulfur recovery process of high-concentration acid gas, which is used for treating H-containing gas2S50v% or more of acid gas, the main equipment comprises a combustion furnace, a two-stage Claus reactor, a selective hydrogenation reduction reactor, a selective oxidation reactor and a depth connected in series in the acid gas flow directionA purification unit and a liquid sulfur tank; the deep purification unit comprises an absorption liquid tower and an adsorbent tower, wherein the circulating absorption liquid is alkali-containing liquid and/or calcium-containing liquid, and the main water source is condensed water of steam contained in the process gas. The process of the invention comprises the steps of introducing COS and CS into a first-stage Claus reactor2Fully hydrolyzing, selectively oxidizing the H in the reactor2S conversion, small amount of SO2Treating in absorption liquid tower to obtain small amount of residual H2S is treated in an adsorbent tower, so that ultralow atmospheric emission is realized; the sulfur collected by the condensed water or the absorption liquid has high purity; the residual liquid of the circulating absorption liquid has low concentration, and is sent to a sewage device and a coal-fired boiler flue gas wet desulphurization unit for treatment or sent to the coal-fired boiler to be used as coal water spraying, and the regeneration period or the agent changing period of the adsorbent tower is long.
Description
Technical Field
The invention relates to a sulfur recovery process, in particular to a sulfur recovery process of high-concentration acid gas.
Background
The acid gas sulfur recovery device is used for recovering the SO of tail gas exhausted from a chimney in the operation process2The concentration is a continuous monitoring project, and in recent years, the emission requirement is more strict, for example, the emission standard of pollutants for petroleum refining industry (GB31570-2015) specifies SO of an acid gas recovery device2Emission concentration limit of 400mg/m3In the areas with higher development density and weakened bearing capacity of resource environment, or the areas with smaller capacity of atmospheric environment, fragile ecological environment and easy occurrence of serious environmental pollution problem, the SO in the areas needs to take special protection measures2Emission concentration limit value is 100mg/m3. Due to H2S、COS、CS2Is a main foul odor pollutant, and the emission concentration should be reduced as much as possible. Some regions also implement more stringent emissions standards or are rewarded with penalties based on emissions.
The acid gas sulfur recovery process in the prior art comprises a combustion furnace, a two-stage Claus reactor, a selective hydrogenation reduction reactor, a selective oxidation reactor and a deep purification unit along the flow direction of acid gas, wherein hydrogen sulfide contained in the acid gas is basically converted into sulfur for recovery, and then the process gas reaches the emission standard and is exhausted through a chimney. Wherein the selective hydrogenation reduction reactor is used for reducing SO contained in the process gas2All reduction to form elemental sulfur and a small amount of H that can be processed in a subsequent selective oxidation reactor2S, the organic sulfur contained is converted into elemental sulfur or H as much as possible2S; o-selective oxidation reactor by introducing air make-up2H is to be2S basicConverted into elemental sulfur, selectively oxidized into elemental sulfur, and a small amount of SO as a byproduct2The idea of process control is to produce less SO on the premise of ensuring the yield of elemental sulfur2Is the main objective to obtain higher H2Off-gas H with a moderately low S conversion2S content is a secondary target, and H in the process gas at the outlet of the selective oxidation reactor2The S content is usually SO2Several times higher than the content of H in the deep purification unit2S is oxidized into elemental sulfur and is recycled, and part of SO is simultaneously used2And (4) disposing. The deep purification unit can adopt a dry active carbon desulfurizer such as loaded alkali or ferric oxide for H2S is adsorbed and oxidized to generate elemental sulfur which is deposited in inner holes or on the surface of active carbon particles, and SO2Is also substantially related to H2S reacting to generate elemental sulfur deposition; or adopting tannin extract method, iron salt method, etc. to treat H2S is absorbed and oxidized to generate elemental sulfur powder which is dispersed in the slurry, and SO2Also substantially absorbed into the slurry, with a minor portion of H2S reacts to generate elemental sulfur, and most of the elemental sulfur is converted into sulfate; the dry and wet desulphurization can be carried out by adding 3000mg/m of process gas3H of (A) to (B)2S treatment to e.g. 10mg/m3Below, to 5 mg/m3Hereinafter, SO2The content can also reach the emission standard, and the treatment of the type remains H2The S method has the advantages that the sulfur yield is high, but after the activated carbon desulfurizer of the dry method penetrates through the activated carbon desulfurizer, the adsorbed and deposited elemental sulfur needs to be blown down by thermal regeneration and condensed and collected, the desulfurizer is relatively troublesome to regenerate, the problems of safety, sanitation, the direction and treatment of the waste desulfurizer and the like exist in the agent changing process, the elemental sulfur obtained in the wet method process needs to be separated from the powder slurry, the prepared sulfur contains more impurities, and the quality is generally poor; in conclusion this is done to reduce the concentration of H in the outlet gas of the selective oxidation reactor to a low level2The process of converting S into elemental sulfur and preparing sulfur has complex equipment and high process control requirement, and can be used for selective hydrogenation reduction of SO in the reactor2The conversion rate requirement is higher, and the atmospheric emission can not reach the standard when the process control of the previous process is insufficient, the operation fluctuation is low or the load is low, so that the method has obvious defects.
Disclosure of Invention
In order to overcome the technical defects, the invention provides a sulfur recovery process of high-concentration acid gas for treating H-containing sulfur2S50v% of acid gas, wherein the main equipment comprises a combustion furnace, a first-stage Claus reactor, a second-stage Claus reactor, a selective hydrogenation reduction reactor, a selective oxidation reactor and a circulating absorption unit which are sequentially connected in series along the flow direction of the acid gas; a waste heat boiler is arranged on the combustion furnace, and a first condenser, a second condenser, a third condenser, a fourth condenser, a fifth heater and a fourth heater are respectively arranged at the front and the back of the Claus reactor, the selective hydrogenation reduction reactor and the selective oxidation reactor; the first condenser to the fifth condenser respectively condense the gaseous sulfur in the process gas into liquid sulfur, and the liquid sulfur flows into a liquid sulfur tank for storage; the first heater, the second heater, the third heater, the fourth heater, the fifth heater, the sixth heater, the fifth heater, the sixth heater, the;
wherein, the upper part of the first-stage Claus reactor is filled with Fe2O3/Al2O3Deoxidizing and protecting type sulfur recovering catalyst with TiO filled in its lower part2Recovering catalyst based on sulfur; the deoxidation protection type sulfur recovery catalyst not only has the Claus reaction activity, but also can be used for removing O in the process gas2Through with H2S reacts to generate elemental sulfur which is removed; the TiO is2Besides the Claus reaction activity, the catalyst for recovering sulfur also can be used for removing COS and CS from the process gas2Near total conversion to elemental sulphur or H2S，COS、CS2The total content is less than or equal to 10mg/m3；
The secondary Claus reactor is filled with sulfur recovery catalyst, and further Claus reaction conversion is carried out under the condition that the temperature is lower than that of the primary Claus reaction, wherein the sulfur recovery catalyst is TiO2Sulfur-based recovery catalyst, TiO2/Al2O3Sulfur recovery catalyst and Al2O3One or two of the sulfur recovery catalysts; h in the process gas at the outlet of the two-stage Claus reactor2S+SO2The content of (A) is less than or equal to 2.0 v%;
selective hydrogenation reduction reactor filled with CoO-MoO3/Al2O3Or CoO-MoO3/ TiO2-Al2O3Selective reduction of SO2Catalyst, using H generated in the furnace2Adding SO2Nearly completely reducing, and the main product is elemental sulfur;
selective oxidation reactor is filled with selective oxidation H2S catalyst, O made up by introducing air before the reactor inlet2H is to be2S is approximately converted completely, is selectively oxidized into elemental sulfur, and the byproduct is a small amount of SO2(ii) a H in the process gas at the outlet of the selective oxidation reactor2S content is less than or equal to 500mg/m3， SO2The content is less than or equal to 1000mg/m3；
The circulating absorption unit comprises an absorption liquid tower and an adsorbent tower which are connected in series, wherein the absorption liquid tower mainly absorbs and treats SO through circulating absorption liquid2And converted into sulfite and sulfate, and the adsorbent tower mainly adsorbs H through a filled adsorption desulfurizer bed layer2S is absorbed and oxidized into elemental sulfur to be removed; the absorption liquid tower is internally provided with a filler and/or a spraying and atomizing part for distributing and contacting the process gas and the circulating absorption liquid, the pH value of the circulating absorption liquid is 5-10, the operation temperature is 20-50 ℃, the main water source is condensed water of steam contained in the process gas, and the surplus liquid outside the normal operation of the circulating absorption liquid is sent to a sewage device for treatment, or sent to a coal-fired boiler flue gas wet desulphurization unit for treatment and used as a supplementary water source, or sent to the coal-fired boiler for use as coal water spray; the circulating absorption liquid is an alkali-containing liquid and/or a calcium-containing liquid, wherein the alkali-containing liquid is a sodium sulfite-containing and/or sodium sulfate solution which maintains the absorption capacity by supplementing sodium hydroxide, sodium carbonate or sodium bicarbonate, and the calcium-containing liquid is a calcium sulfite-containing and/or calcium sulfate-containing slurry which maintains the absorption capacity by supplementing calcium oxide, calcium hydroxide and ultrafine calcium carbonate; when the circulating absorption unit adopts calcium-containing liquid, a sixth condenser is arranged at a process gas inlet of the absorption tower, the process gas is cooled to 20-50 ℃ by the sixth condenser, partial steam is condensed into water, sulfur droplets and powder particles contained in the water are collected to form feed liquid containing sulfur powder, the feed liquid is separated into sulfur powder slurry and then enters the absorption tower or an auxiliary circulating absorption liquid storage tank of the absorption tower, and calcium oxide, calcium hydroxide and superfine calcium carbonate are added into the feed liquidPerforming line circulation absorption;
the sulfur recovery process comprises the following steps:
1) mixing acid gas with required amount of air, then feeding the mixture into a combustion furnace for combustion, controlling the temperature of the combustion furnace at 1100-1350 ℃, feeding process gas generated after combustion into a waste heat boiler and then cooling the process gas to 260-350 ℃, feeding the process gas into a first condensation cooler from an outlet of the waste heat boiler and cooling the process gas to 140-170 ℃, and separating the condensed elemental sulfur generated in the combustion furnace from the process gas and feeding the condensed elemental sulfur into a liquid sulfur tank;
2) heating the process gas from the top of the first condenser to the required temperature of 200-2Hydrolysis of (2); controlling the temperature of the reactor inlet gas to make the TiO in the reactor2The lower part of the catalyst bed layer for recovering sulfur reaches COS and CS2The temperature for full hydrolysis is 320-350 ℃; the outlet process gas enters a second condenser to be cooled to 130-160 ℃, so that the generated elemental sulfur is separated from the process gas and then enters a liquid sulfur tank;
3) heating the process gas from the top of the second condenser to 230 ℃ and then feeding the process gas into a secondary Claus reactor, feeding the outlet process gas into a third condenser and cooling the outlet process gas to 160 ℃ at 130 ℃ so as to separate the generated elemental sulfur from the process gas and then feeding the separated elemental sulfur into a liquid sulfur tank;
4) heating the process gas from the top of the third condenser to 200-220 ℃, and entering the selective reduction reactor; the process gas from the selective reduction reactor enters a fourth condenser to be cooled to 130-150 ℃, and the generated elemental sulfur is separated from the process gas and then enters a liquid sulfur tank;
5) adding required amount of air into the process gas from the top of the fourth condenser, uniformly mixing, heating to 190-210 ℃, and then feeding into a selective oxidation reactor; the process gas from the selective oxidation reactor enters a fifth condenser to be cooled to 120-140 ℃, the generated elemental sulfur is separated from the process gas and then enters a liquid sulfur tank, and the process gas is treated by a circulating absorption unit after being trapped by an optional liquid sulfur trap and flowing into the liquid sulfur tank;
6) the process gas from the top of the fifth condenser or the liquid sulfur trap is circulatedThe absorption unit is treated and then is exhausted through a chimney; when the absorption liquid tower adopts alkali liquor, the temperature of the process gas is reduced, and part of steam is condensed into water, sulfur fog drops, powder particles and most of SO contained in the process gas2And part H2The trapping of S is realized by circulating spraying or atomizing absorption of alkali liquor, the temperature of the alkali liquor is controlled by circulating cooling water, and sulfur powder slurry is separated in the circulation process of the alkali liquor, or the surplus liquid is sent to a sewage device for treatment or a coal-fired boiler flue gas wet desulphurization unit for treatment and is sent to a coal-fired boiler for separation of the sulfur powder slurry before being used as coal spraying water.
In the sulfur recovery process, the first-stage Claus reactor, the second-stage Claus reactor, the selective hydrogenation reduction reactor and the selective oxidation reactor are preferably adiabatic reactors, and the temperature of the middle lower part of a catalyst bed layer reaches the required reaction temperature by controlling the content and the temperature of main reactants in inlet gas and utilizing the exothermic temperature rise of the reaction.
In the sulfur recovery process, the concentration of the acid gas is more than 50v%, SO at the inlet of the first-stage Claus reactor2、H2The S concentration is higher, the temperature rise of the catalyst bed layer of the first-stage Claus reactor can reach 80-130 ℃, so the temperature of the inlet air of the reactor is controlled to be 250 ℃ like 210-2In TiO2The temperature of over 317 ℃ for almost complete hydrolysis and conversion of the sulfur-based recovery catalyst, and COS and CS in the outlet gas of the first-stage Claus reactor2The total content is easy to be less than or equal to 10mg/m3This is a key aspect of the process because such high catalyst bed temperatures are not easily achieved in the post-process and yet conditions are convertible to elemental sulfur; some can hydrolyze COS and CS at lower temperature such as 250 deg.C2Including TiO-containing catalysts modified by oxides or salts of, for example, alkaline earth metals, transition metals, rare earth metals2Catalyst for hydrolyzing COS and CS2Can be as active and as precise as required, but generally have a much shorter lifetime than the TiO used in the present invention2Recovering catalyst based on sulfur; TiO used in the invention2Based on catalysts for sulfur recovery, containing TiO2More than 85m percent, and the balance being calcium sulfateSurface area of the binder is 100-2G, pore volume 0.20-0.35 ml/g.
In the sulfur recovery process of the invention, the selective oxidation of H2S catalyst comprising Fe2O3/SiO2Or H modified by oxides of alkaline earth metals, transition metals2S selective oxidation catalyst of Fe2O33-10m%, alkaline earth metal oxide such as CaO 0-3m%, and transition metal oxide such as Cr2O30-5 m%; the catalyst has average pore diameter of above 30nm, preferably above 35nm, and surface area of 40-60m2The advantages of the catalyst are that liquid sulfur is not condensed to block pores or liquid sulfur is less condensed to block pores in smaller diameter pores at lower bed temperature, thereby ensuring that the activity and reaction degree of the catalyst meet the requirements.
In the sulfur recovery process, the selective oxidation reactor can remove more than 95 percent of H2S is converted to generate elemental sulfur and SO which is easy to absorb and treat in subsequent circulating alkali liquor and calcium liquor to reach the standard2At the outlet of the reaction gas O2The catalyst has stable performance and the service life is more than 5 years under the condition that the content is less than 1 v%.
In the sulfur recovery process, when the circulating absorption unit adopts the calcium-containing liquid, the sixth condenser arranged at the process gas outlet of the fifth condenser and the process gas inlet of the calcium liquid circulating absorption unit can adopt a conventional shell-and-tube heat exchanger, particularly a shell-and-tube heat exchanger with fins, wherein the process gas flows through the shell side, and the cooling water flows through the tube side; cooling to 10-50 deg.C, condensing most of steam in the process gas into water on the heat exchange surface, condensing sulfur droplets and sulfur steam carried by the process gas into sulfur powder, collecting the sulfur powder in condensate water, and collecting part of SO in the process gas with the condensate water2、H2S is dissolved and trapped, gas in the heat exchanger enters from bottom to top, the cooling water pipe is integrally from top to bottom, sulfur powder is basically trapped at the middle lower part of the cooling water pipe and at a position where more condensed water exists, the sulfur powder enters the condensed water as much as possible to form slurry and flows out of the heat exchanger, and the sulfur powder is deposited on the surface of the cooling water pipe at the upper part as little as possible to keep the effect of the heat exchanger; coldThe plane of the fin outside the water pipe is preferably arranged in the vertical direction, so that the deposition and condensation of sulfur powder on the surface of the fin are reduced. The heat exchanger can switch the cooling water into superheated steam with the temperature of 250 ℃ on the tube pass when the efficiency is reduced so as to melt, evaporate and remove the sulfur deposited on the heat exchange surface, and the subsequent alkali liquor circulation absorption can temporarily play the role of the heat exchanger. The sixth condenser can also have a structure other than a shell-and-tube heat exchanger, such as the sulfur-containing powder and SO2、H2The condensate of S is used as circulating liquid to realize gas-liquid contact, process gas cooling, sulfur capture and partial SO by spraying and/or atomizing2、H2S is dissolved and absorbed, the condensate is controlled to be at a proper low temperature by cooling water through a liquid-liquid heat exchanger, and the condensing method has the advantages of small loss of process gas pressure head and small influence of sulfur deposition on the condensing effect.
In the sulfur recovery process, the separation of the condensate containing the sulfur powder and the sulfur powder in the alkali-containing solution can be carried out by cyclone sedimentation or natural sedimentation to obtain sulfur powder slurry with higher sulfur powder content; further filtering and separating, or concentrating and accumulating, pressurizing and heating with steam to melt and stratify sulfur powder contained therein, and delivering liquid sulfur to a liquid sulfur tank. Because the concentration of salt such as sodium sulfate, sodium sulfite, sodium hydrosulfide and the like in the alkali-containing liquid for trapping the sulfur powder is low (less than 1m percent and generally less than 0.5m percent), the condensate of the sixth condenser hardly contains sulfate, sulfite and solid components except the sulfur powder, so that the generated sulfur powder and the separated sulfur powder slurry contain less impurities, are cleaner and have purity far higher than that of wet oxidation absorption H of iron salt components such as tannin extract and iron oxyhydroxide2S to obtain sulfur powder slurry or sulfur. The washing water and the heated sulfur-dissolving hot water of the sulfur powder slurry can be returned to the absorption liquid tower.
In the sulfur recovery process, the circulating absorption liquid maintains the normal operation, and the rich residual liquid containing sodium sulfate, sodium sulfite and a small amount of sodium hydrosulfide or the rich residual slurry containing calcium sulfate, calcium sulfite and a small amount of calcium hydrosulfide is sent to a sewage device for treatment, or sent to a wet flue gas desulfurization unit of a coal-fired boiler for treatment and used as a supplementary water source and a raw material, or sent to the coal-fired boiler for coal water spraying, wherein the sewage device and the coal-fired boiler are used as coal water spraying waterThe coal boiler flue gas treatment device has the advantages of more perfect facility conditions and higher management control level, is easy to treat the sulfate, sulfite and a small amount of hydrosulfide solution or slurry of the separated sulfur powder to the standard discharge or recycling level, and has more loose requirements as coal water spraying. Wherein, the mainstream process of the wet desulphurization of the flue gas of the coal-fired boiler is a calcium carbonate-calcium sulfate method, and slurry containing calcium carbonate is sprayed or atomized to absorb SO contained in the flue gas2Generating calcium sulfite, or wet desulphurization by a sodium-calcium double-alkali method, and absorbing SO by sodium hydroxide and/or soda ash2Adding lime to generate calcium sulfite and regenerating alkali; the obtained calcium sulfite is oxidized into calcium sulfate by blown air, and then the calcium sulfate is separated and utilized. The rich residual liquid containing sodium sulfate, sodium sulfite and a small amount of sodium hydrosulfide is preferably sent to the wet desulphurization by a sodium-calcium double alkali method, and the rich slurry containing calcium sulfate and calcium sulfite can be sent to any one of the wet desulphurization by a calcium carbonate-calcium sulfate method or a sodium-calcium double alkali method. The surplus liquid containing sodium sulfate, sodium sulfite and a small amount of sodium hydrosulfide and the surplus slurry containing calcium sulfate, calcium sulfite and a small amount of calcium hydrosulfide have simple components, almost do not contain organic components, have small quantity, and are easy to treat in sewage devices and flue gas desulfurization devices of coal-fired boilers, because the contained water is condensed water of steam in process gas, the added alkali and calcium raw materials are simple and nontoxic, wherein the sodium hydrosulfide and the calcium hydrosulfide have low content and can be finally converted into sulfate without causing H emission2S leads to a risk of harm. Circulating absorption liquid pair H2The absorption capacity of S can be controlled by adjusting the pH value of the S, the absorption capacity is smaller when the pH value of the absorption liquid is lower, such as 5-6, and the absorption capacity is slightly larger when the pH value of the absorption liquid is higher, such as 6-8; when the allowable value of the absorption of the hydrosulphide and/or the sulphide in the rich residual liquid is higher in the sewage treatment device, the wet flue gas desulfurization unit of the coal-fired boiler or the coal water drenching of the coal-fired boiler, the higher pH value of the absorption liquid can be adopted, such as 8-8.5, and the advantage is that the pH value of the H absorption liquid is higher2The S absorption rate is high, the period of replacement or regeneration of the adsorption desulfurization tower is long, and the process gas usually contains CO with low concentration2Above pH 8.5 is generally not achievable.
In the sulfur recovery process of the invention, the enrichment is realizedThe residual absorption liquid is sent to a sewage device for treatment, or sent to a coal-fired boiler flue gas wet desulphurization unit for treatment and used as a supplementary water source and raw materials, or sent to the coal-fired boiler as coal shower, the dosage of alkali or calcium can be properly relaxed, i.e. higher dosage or concentration is adopted, SO that the circulating absorption liquid has higher absorption capacity, if the pH value of alkali liquor can be higher, the absorption capacity for SO is preferentially ensured2、H2The absorption capacity of S ensures that the concentration of the atmospheric emission reaches the standard or is lower, but is not higher than the utilization rate of alkali and calcium; the method meets the requirements of users or downstream users without excessively counting whether the crystallization condition of the calcium sulfate reaches the standard, and because the amount of the absorption liquid, the concentration of alkali and calcium contained in the absorption liquid are usually far lower than the liquid amount and the concentration of the absorption liquid during the wet desulphurization of the flue gas of the coal-fired boiler, the absorption liquid can not cause obvious influence on the absorption liquid.
The sulfur recovery process utilizes the process gas H2The condensed water of the steam byproduct generated in S oxidation sulfur production is used as a water source of the circulating absorption unit, and special supplement and control of water are not needed. Different H2The process gas with S content acid gas contains condensate amounts of steam at different condensing temperatures as listed in table 1 below. Calculating conditions: h in acid gas2S reacts with the required amount of air to be converted into sulfur, and the air is not excessive; the saturated vapor pressure of water is 12kPa at 50 ℃ and 7.4kPa at 40 ℃; the acid gas does not contain components such as hydrocarbon and ammonia which can react with air to generate water.
TABLE 1 number of condensates of steam contained in the process gas at different condensation temperatures
According to the amount of the condensed water listed in Table 1, the concentrations of the sulfate and the sulfite in the circulating absorption liquid are easily controlled within 1m%, even within 0.5m%, and even the slurry containing the calcium sulfate and the calcium sulfite is easily transported for a long distance; fog drops discharged from the top end of the chimney and entering the chimney and the atmosphere contain less salt, the corrosion to the chimney is much lighter, colored smoke plume is not easy to generate when the smoke is discharged from the top end of the chimney, white powder particles are not easy to float on the ground near the chimney at low wind speed, and the white powder particles are circulated in absorption liquidThe concentration of the sulfate and the sulfite is far lower than that of SO treated by the prior alkali method, calcium method and ammonia method2The circulating absorption liquid of (2) has a high concentration level of sulfite and sulfate of more than 10 m%. The existing alkali method, calcium method and ammonia method technologies for treating SO2In the circulating absorption liquid, because the sulfite and the sulfate are contained in the circulating absorption liquid, the general demister has poor trapping capacity on salt-containing liquid drops with the diameter of less than 2.5 mu m, process gas containing sulfite and sulfate liquid drops with high concentration enters a chimney and the atmosphere and corrodes the chimney, visible smoke plume is easily generated when the gas is exhausted from the top end of the chimney, and white particles are easily drifted off on the ground near the chimney at low wind speed. H2The product of S in the absorption liquid is also easily converted into harmless substances such as sulfates during the treatment or use of the rich absorption liquid.
The circulating absorption unit is connected in series with the adsorbent tower behind the absorption liquid tower, and the filled adsorption desulfurizing agent comprises conventional Fe2O3Active carbon desulfurizer and FeOOH desulfurizer, and the desulfurization precision and capacity of the two desulfurizers are basically not influenced by CO in process gas2Influence of the content H2The S removal precision can reach 1mg/m3The sulfur capacity can reach more than 30m percent and even more than 40 m percent, wherein Fe2O3The activated carbon desulfurizer can be regenerated by blowing off elemental sulfur deposited on inner holes and surfaces through steam or inert gas at about 250 ℃, and basically recovers the desulfurization precision and capacity for long-term use. When the inlet H of the adsorbent tower is2S content higher than SO2At a multiple of the content, Fe2O3Active carbon desulfurizer and FeOOH desulfurizer can also remove part of SO2But SO2The absorption cost in the alkali liquor and calcium liquor absorption tower is lower. The sulfur recovery process can use the SO in the process gas by connecting the absorption liquid tower and the adsorbent tower in series2、H2S is treated to a lower content level to meet the requirement of ultra-low emission. In order to reduce the influence of fine solid salt-containing liquid drops carried by the process gas on the desulfurizer bed layer of the adsorbent tower, the absorption liquid tower can adopt a packed tower, and a defogging component such as a corrugated net or a baffling component can be arranged at the top of the absorption liquid tower during spray absorption.
The first heater, the second heater, the third heater, the fourth heater, the fifth condenser and the fifth condenser are combined together, and the heating and heat exchanging modes can be combined together.
In the sulfur recovery process, a small amount of process gas after the cyclic absorption treatment can be used as purge gas to purify a liquid sulfur tank and liquid sulfur and returns to an acid gas storage tank in front of a combustion furnace, so that H contained in the liquid sulfur is removed2And S and the like are recycled.
In the sulfur recovery process, the process gas after cyclic absorption can be heated to 75 ℃ or above through heat exchange and then enters the chimney for evacuation, steam in the process gas is unsaturated, condensate is not generated in the chimney basically, corrosion to the chimney is reduced, the service life is prolonged, and no smoke plume can be seen at the top end of the chimney basically.
The process gas outlet section in the fifth condenser can be provided with one or more layers of baffle members or silk screens and fillers made of stainless steel or PTFE materials, and liquid sulfur droplets are collected by falling back by utilizing the self gravity of the liquid sulfur. And a liquid sulfur mist catcher can be optionally arranged behind the second condenser, the mist catcher collects the liquid sulfur droplets in the gas, the liquid sulfur droplets fall back by utilizing the self gravity of the liquid sulfur and are collected into the liquid sulfur, and a mist catching part of the liquid sulfur mist catcher is a baffle made of stainless steel or PTFE material or a wire mesh or filler.
The main advantages of the sulfur recovery process of the invention include:
1. the deep purification unit utilizes condensed water added with alkali or calcium as absorption liquid to deeply treat SO2And circulating the absorption liquid to SO2The processing capacity of the reactor is very high, the reactor is easy to control, the operation requirements on a selective hydrogenation reduction reactor and a selective oxidation reactor are reduced, and the operation flexibility of the two reactors and a Claus reaction section is increased;
2. the selective oxidation reactor has wider operation flexibility because a little more SO can be generated2，H2The conversion rate of S can be controlled to a high limit, so that the H of the inlet gas of the deep purification unit2S is reduced, and a part of H can be absorbed by the circulating absorption liquid2S, so the load of the dry desulfurization tower is reduced, and the regeneration period or the agent changing period is long;
3. the exhaust air is easy to reach and ensure the ultra-low emission and the generation of SO2The probability of over-standard emission is greatly reduced;
4. the sulfur recovery process does not need an incinerator, and the problems of fuel consumption, supply and cost do not exist.
Drawings
FIG. 1 is a schematic process flow diagram of the acid gas sulfur recovery process of the present invention.
The equipment numbers in fig. 1 are in sequence: 1 combustion furnace, 2 waste heat boiler, 3 first condenser, 4 second condenser, 5 third condenser, 6 fourth condenser, 7 fifth condenser, 8 sixth condenser, 9 first heater, 10 second heater, 11 third heater, 12 fourth heater, 13 first-stage Claus reactor, 14 second-stage Claus reactor, 15 selective hydrogenation reduction reactor, 16 selective oxidation reactor, 17 adsorbent tower, 18 sulfur slurry knockout drum, 19 circulating pump, 20 liquid sulfur trough, 21 chimney, 22 absorption liquid tower.
Detailed Description
Some process parameter experiments are carried out on a set of 10000 ton/year scale acid gas sulfur recovery device, and absorption treatment experiments are carried out on the process gas at the outlet of the fifth condenser behind the selective oxidation reactor, so as to explain the process of the invention, but not to limit the process of the invention.
The sulfur recovery device comprises a combustion furnace, a first-stage Claus reactor, a second-stage Claus reactor, a selective hydrogenation reduction reactor, a selective oxidation reactor and a circulating absorption unit which are sequentially connected in series along the acid gas flow direction; a waste heat boiler is arranged on the combustion furnace, and a first condenser, a second condenser, a third condenser, a fourth condenser, a fifth heater and a fourth heater are respectively arranged at the front and the back of the Claus reactor, the selective hydrogenation reduction reactor and the selective oxidation reactor; the first condenser to the fifth condenser respectively condense the gaseous sulfur in the process gas into liquid sulfur, and the liquid sulfur flows into a liquid sulfur tank for storage; the first heater, the second heater, the third heater, the fourth heater, the fifth heater, the sixth heater, the fifth heater, the sixth heater, the; wherein, the upper part of the first-stage Claus reactor is filled with Fe2O3/Al2O3Deoxidizing and protecting type sulfur recovering catalyst with TiO filled in its lower part2Recovering catalyst based on sulfur; filling TiO in secondary Claus reactor2Recovering catalyst based on sulfur; selective hydrogenation reduction reactor filled with CoO-MoO3/Al2O3Selective reduction of SO2A catalyst; selective oxidation reactor charging with Fe2O3-Cr2O3/SiO2Selective oxidation of H2And (4) an S catalyst.
In the normal process of the sulfur recovery device, the process gas at the outlet of a fifth condenser behind the selective oxidation reactor is treated by an activated carbon desulfurizer tower and then exhausted by a chimney of 110 m; the acid gas treated during the experiment contained H2S60-80v% or so.
In order to verify the process of the invention, a small-sized sixth condenser, a circulating absorption liquid tower and an adsorption desulfurizer tower experimental device are arranged behind the fifth condenser, and the process gas is fed by 1.0-1.1m3The flow rate per minute (measured after the sixth condenser) is introduced into the sixth condenser, the circulating absorption liquid tower and the absorption desulfurizer tower from a pipeline branch pipe at the outlet of the fifth condenser; the circulating absorption liquid tower is a transparent plastic cylinder, an absorption liquid circulating pump is arranged outside the transparent plastic cylinder, the bottom of the absorption liquid tower is also used as an absorption liquid storage tank, an atomizing nozzle is arranged at the top in the absorption liquid tower, the hollow cylinder part at the upper middle part of the absorption tower is an absorption liquid atomizing absorption space, and the atomizing nozzle can effectively distribute absorption liquid and fill the atomizing absorption space to play a role in full absorption; the sixth condenser cools the temperature to 40 ℃ through circulating water, condensate discharged from a liquid outlet at the bottom passes through a small transparent plastic cylinder, the condensate is settled and collected to flow into the bottom of the absorption liquid tower to be used as make-up water for circulating absorption liquid, and an exhaust port is connected with the middle lower part of the absorption liquid tower to feed process gas; two layers of corrugated silk screens are arranged at the top of the absorption liquid tower for demisting and exhausting, and exhausted gas is discharged into the site environment after being treated by a desulfurizer tower filled with a FeOOH desulfurizer and a NaOH/active carbon tower. Respectively using NaHCO with the concentration of 0.5m%3Solution, 0.5m% of ultrafine CaCO3The slurry is used as the absorption liquid of the circulating absorption liquid tower.
The main process parameters of the first stage of the experiment include:
the temperature of a combustion furnace is 1250 ℃, the temperature of the process gas after the waste heat boiler is 350 ℃, the temperature of the process gas at the outlet of the first condenser is 168 ℃, and the temperature of H is about2S5.1v%，SO23.0v%，COS+CS20.5v%；
The temperature of the process gas at the outlet of the first heater is 220 ℃, the temperature of the lower part of the catalyst bed layer of the first-stage Claus reactor is 326 ℃, the temperature of the process gas at the outlet of the second condenser is 150 ℃, and the temperature of H is H2S 2.1v%，SO21.0v%，COS+CS2≤3mg/m3；
The temperature of the process gas at the outlet of the second heater is 204 ℃, the temperature of the lower part of the catalyst bed layer of the second-stage Claus reactor is 230 ℃, the temperature of the process gas at the outlet of the third condenser is 140 ℃, and the temperature of H is H2S0.9v%，SO20.4v%；
The temperature of the process gas at the outlet of the third heater is 206 ℃, the temperature of the lower part of the catalyst bed layer of the selective hydrogenation reduction reactor is 240 ℃, the temperature of the process gas at the outlet of the fourth condenser is 140 ℃, and the temperature of H is2S0.7v%，SO2≤20mg/m3；
Adding required amount of air into the process gas at the outlet of the fourth condenser, uniformly mixing the air and the process gas in the fourth heater, wherein the temperature of the process gas at the outlet is 190 ℃, the temperature of the lower part of a catalyst bed layer of the selective oxidation reactor is 227 ℃, the temperature of the process gas at the outlet of the fifth condenser is 135 ℃, and H is2S350-400mg/m3，SO2200-300mg/m3，O20.5-0.8v%，CO2About 12v%, the balance being steam and N2；
The outlet gas temperature of the sixth condenser is 40 ℃, and the condensate amount of a bottom liquid outlet is about 200-;
the absorption liquid of the absorption liquid tower adopts 0.5m% NaHCO3In the solution, the pH of the absorption liquid is about 8 at the initial stage, and the gas H at the outlet of the absorption liquid tower2S160-200mg/m3，SO2≤8mg/m3Outlet gas H of desulfurizing agent tower2S≤1mg/m3，SO2≤5mg/m3，COS+CS2≤5mg/m3(ii) a Calculating NaHCO according to the amount of treated gas and the amount of absorbed liquid3When 80% is consumed, the pH value of the absorption liquid is about 6, and the outlet gas H of the absorption liquid tower2S280-330mg/m3，SO2≤15mg/m3Outlet gas of desulfurizing agent towerH2S≤1mg/m3，SO2≤10mg/m3，COS+CS2≤5mg/m3；
The absorption liquid of the absorption liquid tower adopts 0.5m percent CaCO3When the slurry is in use, the initial pH value is about 5.5, and the outlet gas H of the absorption liquid tower2S300-340mg/m3，SO2≤15mg/m3(ii) a CaCO calculation from the amount of gas treated and the amount of liquid absorbed3When 60% is consumed, the outlet gas H of the absorption liquid tower2S330-360mg/m3，SO2≤20mg/m3，COS+CS2≤6mg/m3。
The main process parameters of the second stage of the experiment include:
the temperature of the combustion furnace is about 1300 ℃, the temperature of the process gas after the waste heat boiler is 350 ℃, the temperature of the process gas at the outlet of the first condenser is 170 ℃, and the temperature H is about 1300 DEG2S4.9v%， SO22.5v%，COS+CS20.4v%；
The temperature of the process gas at the outlet of the first heater is 237 ℃, the temperature of the lower part of the catalyst bed layer of the first-stage Claus reactor is 328 ℃, the temperature of the process gas at the outlet of the second condenser is 150 ℃, and the temperature of H is2S 1.7v%，SO20.7v%，COS+CS2≤3mg/m3；
The temperature of the process gas at the outlet of the second heater is 210 ℃, the temperature of the lower part of the catalyst bed layer of the second-stage Claus reactor is 235 ℃, the temperature of the process gas at the outlet of the third condenser is 140 ℃, and the temperature of H is H2S0.8v%，SO20.2v%；
The temperature of the process gas at the outlet of the third heater is 220 ℃, the temperature of the lower part of the catalyst bed layer of the selective hydrogenation reduction reactor is 235 ℃, the temperature of the process gas at the outlet of the fourth condenser is 140 ℃, and the temperature of H is2S0.6v%，SO2≤20mg/m3；
Adding required amount of air into the process gas at the outlet of the fourth condenser, uniformly mixing the air and the process gas in the fourth heater, wherein the temperature of the process gas at the outlet is 190 ℃, the temperature of the lower part of a catalyst bed layer of the selective oxidation reactor is 224 ℃, the temperature of the process gas at the outlet of the fifth condenser is 135 ℃, and H is H2S250-300mg/m3，SO2220-260mg/m3，O20.8-1.0v%，CO2About 12v%, the balance being steam and N2；
The outlet gas temperature of the sixth condenser is 40 ℃, and the condensate amount of a bottom liquid outlet is about 200-;
the absorption liquid of the absorption liquid tower adopts 0.5m% NaHCO3In the case of solution, the initial pH is about 8, and the gas H at the outlet of the absorption liquid tower2S150-180mg/m3，SO2≤8mg/m3Outlet gas H of desulfurizing agent tower2S≤1mg/m3，SO2≤5mg/m3，COS+CS2≤4mg/m3(ii) a Calculating NaHCO according to the amount of treated gas and the amount of absorbed liquid3When 80% of the gas is consumed, the gas H at the outlet of the absorption liquid tower2S190-210mg/m3，SO2≤12mg/m3，COS+CS2≤4mg/m3；
The absorption liquid of the absorption liquid tower adopts 0.5m percent CaCO3When the slurry is in use, the initial pH value is about 6, and the outlet gas H of the absorption liquid tower2S200-220mg/m3，SO2≤15mg/m3Outlet gas H of desulfurizing agent tower2S≤1mg/m3，SO2≤10mg/m3，COS+CS2≤4mg/m3(ii) a CaCO calculation from the amount of gas treated and the amount of liquid absorbed3When 60% is consumed, the outlet gas H of the absorption liquid tower2S220-240mg/m3，SO2≤20mg/m3，COS+CS2≤4mg/m3。
In the above two-stage experiments, the condensate discharged from the liquid outlet at the bottom of the sixth condenser is collected and settled in the transparent plastic cylinder, the sulfur slurry obtained at the bottom layer has yellow color and is easy to settle and filter, the supernatant is clear, and the sulfur obtained by filtering has purity higher than 99.5m% after being simply washed and dried, and has purer and more positive color. The sulfur slurry has good quality, can be pumped and pressurized by a pump when a certain amount of sulfur slurry is accumulated, is melted by low-pressure steam, and the separated liquid sulfur directly enters a liquid sulfur trough for recovery.
The 0.5m% NaHCO is treated by the sewage treatment device and coal-fired boiler device personnel of the company380% CaCO consumption of the solution and 0.5m% CaCO consumption3The absorption raffinate containing sulfate, sulfite and a small amount of sulfide when the slurry consumed 60% was examined in detail for inorganic components and organic components, and it was considered that the inorganic components were simple, the content was low, and the organic components were hardly contained,compared with the treatment capacity or demand of a sewage treatment device, a coal-fired boiler flue gas wet desulphurization unit or coal water spraying, the sulfur recovery process has small liquid discharge amount when being used in an industrial device, can be sent to a sewage device for treatment and discharge, and can also be sent to a coal-fired boiler flue gas wet desulphurization unit for utilization and used as coal water spraying.
The sulfur recovery process of the invention is used in the outlet gas of the absorption tower in an industrial device, namely SO2The content meets the requirement of ultra-low emission, H2S、COS、CS2The content of the odor substances is extremely low, the emission requirement is met, and the odor substances can be exhausted through a chimney.
Claims (9)
1. A sulfur recovery process for treating H-containing gas2S50v% of acid gas, wherein the main equipment comprises a combustion furnace, a first-stage Claus reactor, a second-stage Claus reactor, a selective hydrogenation reduction reactor, a selective oxidation reactor and a circulating absorption unit which are sequentially connected in series along the flow direction of the acid gas; a waste heat boiler is arranged on the combustion furnace, and a first condenser, a second condenser, a third condenser, a fourth condenser, a fifth heater and a fourth heater are respectively arranged at the front and the back of the Claus reactor, the selective hydrogenation reduction reactor and the selective oxidation reactor; the first condenser to the fifth condenser respectively condense the gaseous sulfur in the process gas into liquid sulfur, and the liquid sulfur flows into a liquid sulfur tank for storage; the first heater, the second heater, the third heater, the fourth heater, the fifth heater, the sixth heater, the fifth heater, the sixth heater, the;
wherein, the upper part of the first-stage Claus reactor is filled with Fe2O3/Al2O3Deoxidizing and protecting type sulfur recovering catalyst with TiO filled in its lower part2Recovering catalyst based on sulfur; the deoxidation protection type sulfur recovery catalyst not only has the Claus reaction activity, but also can be used for removing O in the process gas2Through with H2S reacts to generate elemental sulfur which is removed; the TiO is2Besides the Claus reaction activity, the catalyst for recovering sulfur also can be used for removing COS and CS from the process gas2Near total conversion to elemental sulphur or H2S，COS、CS2The total content is less than or equal to 10mg/m3；
The secondary Claus reactor is filled with sulfur recovery catalyst, and further Claus reaction conversion is carried out under the condition that the temperature is lower than that of the primary Claus reaction, wherein the sulfur recovery catalyst is TiO2Sulfur-based recovery catalyst, TiO2/Al2O3Sulfur recovery catalyst and Al2O3One or two of the sulfur recovery catalysts; h in the process gas at the outlet of the two-stage Claus reactor2S+SO2The content of (A) is less than or equal to 2.0 v%;
selective hydrogenation reduction reactor filled with CoO-MoO3/Al2O3Or CoO-MoO3/ TiO2-Al2O3Selective reduction of SO2Catalyst, using H generated in the furnace2Adding SO2Nearly completely reducing, and the main product is elemental sulfur;
selective oxidation reactor is filled with selective oxidation H2S catalyst, O made up by introducing air before the reactor inlet2H is to be2S is approximately converted completely, is selectively oxidized into elemental sulfur, and the byproduct is a small amount of SO2(ii) a H in the process gas at the outlet of the selective oxidation reactor2S content is less than or equal to 500mg/m3， SO2The content is less than or equal to 1000mg/m3(ii) a The selective oxidation of H2S catalyst is SiO2As a carrier, Fe2O33-10m%，CaO 0-3m%，Cr2O30-5 m%; the average pore diameter of the catalyst is more than 30nm, and the surface area is 40-60m2G, pore volume 0.5-0.6 ml/g;
the circulating absorption unit comprises an absorption liquid tower and an adsorbent tower which are connected in series, wherein the absorption liquid tower mainly absorbs and treats SO through circulating absorption liquid2And converted into sulfite and sulfate, and the adsorbent tower mainly adsorbs H through a filled adsorption desulfurizer bed layer2S is absorbed and oxidized into elemental sulfur to be removed; the absorption liquid tower is internally provided with a filler and/or a spraying and atomizing component for distributing and contacting the process gas and the circulating absorption liquid, the pH of the circulating absorption liquid is 5-10, the operation temperature is 20-50 ℃, the main water source is condensed water of steam contained in the process gas, and the circulating absorption liquid is sent to surplus liquid outside the normal operation of the circulating absorption liquidTreating the wastewater in a sewage device, or treating the wastewater in a wet flue gas desulfurization unit of a coal-fired boiler and using the treated wastewater as a supplementary water source, or sending the wastewater to the coal-fired boiler to be used as coal water spray, wherein the circulating absorption liquid is alkali-containing liquid and/or calcium-containing liquid, the alkali-containing liquid is sodium sulfite and/or sodium sulfate solution which maintains the absorption capacity by supplementing sodium hydroxide, sodium carbonate or sodium bicarbonate, and the calcium-containing liquid is calcium sulfite and/or calcium sulfate slurry which maintains the absorption capacity by supplementing calcium oxide, calcium hydroxide and superfine calcium carbonate; when the circulating absorption unit adopts calcium-containing liquid, a sixth condenser is arranged at a process gas inlet of the absorption tower, the process gas is cooled to 20-50 ℃ through the sixth condenser, part of steam is condensed into water, sulfur droplets and powder particles contained in the water are collected to form feed liquid containing sulfur powder, the feed liquid is separated into sulfur powder slurry and then enters the absorption tower or an auxiliary circulating absorption liquid storage tank of the absorption tower, and calcium oxide, calcium hydroxide and superfine calcium carbonate are added for circulating absorption;
the sulfur recovery process comprises the following steps:
1) mixing acid gas with required amount of air, then feeding the mixture into a combustion furnace for combustion, controlling the temperature of the combustion furnace at 1100-1350 ℃, feeding process gas generated after combustion into a waste heat boiler and then cooling the process gas to 260-350 ℃, feeding the process gas into a first condensation cooler from an outlet of the waste heat boiler and cooling the process gas to 140-170 ℃, and separating the condensed elemental sulfur generated in the combustion furnace from the process gas and feeding the condensed elemental sulfur into a liquid sulfur tank;
2) heating the process gas from the top of the first condenser to the required temperature of 200-2Hydrolysis of (2); controlling the temperature of the reactor inlet gas to make the TiO in the reactor2The lower part of the catalyst bed layer for recovering sulfur reaches COS and CS2The temperature for full hydrolysis is 320-350 ℃; the outlet process gas enters a second condenser to be cooled to 130-160 ℃, so that the generated elemental sulfur is separated from the process gas and then enters a liquid sulfur tank;
3) heating the process gas from the top of the second condenser to 230 ℃ and then feeding the process gas into a secondary Claus reactor; the outlet process gas enters a third condenser to be cooled to 130-160 ℃, so that the generated elemental sulfur is separated from the process gas and then enters a liquid sulfur tank;
4) heating the process gas from the top of the third condenser to 200-220 ℃ and then entering the selective reduction reactor; the process gas from the selective reduction reactor enters a fourth condenser to be cooled to 130-150 ℃, and the generated elemental sulfur is separated from the process gas and then enters a liquid sulfur tank;
5) adding required amount of air into the process gas from the top of the fourth condenser, uniformly mixing, heating to 190-210 ℃, and then feeding into a selective oxidation reactor; the process gas from the selective oxidation reactor enters a fifth condenser to be cooled to 120-140 ℃, the generated elemental sulfur is separated from the process gas and then enters a liquid sulfur tank, and the process gas is treated by a circulating absorption unit after being trapped by an optional liquid sulfur trap and flowing into the liquid sulfur tank;
6) the process gas from the top of the fifth condenser or the liquid sulfur catcher enters the circulating absorption unit for treatment and then is exhausted through a chimney; when the absorption liquid adopts alkali solution, the temperature of the process gas is reduced, part of steam is condensed into water, sulfur fog drops, powder particles and most of SO contained in the process gas2And part H2The trapping of S is realized by circulating spraying or atomizing absorption of alkali liquor, the temperature of the alkali liquor is controlled by circulating cooling water, and sulfur powder slurry is separated in the circulation process of the alkali liquor, or the surplus liquid is sent to a sewage device for treatment or a coal-fired boiler flue gas wet desulphurization unit for treatment and is sent to a coal-fired boiler for separation of the sulfur powder slurry before being used as coal spraying water.
2. The process for sulfur recovery from acid gas of claim 1, wherein the primary claus reactor, the secondary claus reactor, the selective hydrogenation reduction reactor, and the selective oxidation reactor are adiabatic reactors.
3. The process for sulfur recovery from acid gas of claim 1, wherein the primary claus reactor is charged with the catalyst, and wherein the TiO is in the catalyst2Based on catalysts for sulfur recovery, containing TiO2More than 85m percent, the balance being calcium sulfate binder, the surface area being 100-130m2G, pore volume 0.20-0.35 ml/g.
4. The process for recovering the sulfur from the acid gas according to claim 1, wherein the circulating absorption unit is a sixth condenser arranged when the calcium-containing liquid is adopted, the gas enters from the bottom to the top, and the cooling water pipe is arranged from the top to the bottom as a whole, so that the sulfur powder is captured at the middle lower part and the position with more condensed water of the cooling water pipe to form slurry which flows out of the heat exchanger.
5. The process for recovering the sulfur from the acid gas as claimed in claim 1, wherein the separation of the sulfur powder in the condensate containing the sulfur powder and the alkali-containing solution in the circulating absorption unit is carried out by cyclone sedimentation or natural sedimentation to obtain a sulfur powder slurry with higher content of the sulfur powder; the sulfur powder slurry is further filtered and separated, or after concentration and accumulation, the sulfur is pressurized and heated by steam to melt the sulfur, and after layering, the liquid sulfur is sent to a liquid sulfur tank.
6. The process for recovering sulfur from acid gas according to claim 1, wherein the surplus solution containing sodium sulfate and sodium sulfite, which is obtained after the circulating absorption solution is maintained in normal operation, is sent to the sodium-calcium double alkali wet desulfurization; and (3) sending the surplus slurry containing calcium sulfate and calcium sulfite to a calcium carbonate-calcium sulfate method or a sodium-calcium double-alkali wet desulphurization method.
7. The process for recovering sulfur from acid gas according to claim 1, wherein the amount of the alkali-containing raw material fed or concentrated in the circulating absorption solution is 20% or more higher than the required amount, and the amount of the calcium-containing raw material fed or concentrated is 40% or more higher than the required amount.
8. The process for recovering sulfur from acid gas as defined in claim 1, wherein a small amount of process gas after said cyclic absorption treatment is used as a purge gas to purify a liquid sulfur tank and liquid sulfur and returned to the acid gas storage tank before the combustion furnace; and/or the process gas after the cyclic absorption treatment is heated to more than 75 ℃ through heat exchange and then enters a chimney for evacuation.
9. The process for recovering the sulfur from the acid gas as claimed in claim 1, wherein the first to fourth heaters are realized by medium-high pressure steam, heat conducting oil and fuel combustion and/or are combined with the first to fifth condensers to perform countercurrent heat exchange; and/or a process gas outlet section in the fifth condenser is provided with one or more layers of baffle members or silk screens made of stainless steel or PTFE materials and fillers for trapping liquid sulfur fog drops, and the liquid sulfur is collected as liquid sulfur by falling back by utilizing the self gravity of the liquid sulfur.
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