MXPA00002441A - High efficiency process for recovering sulfur from h2 - Google Patents

Abstract

The present invention concerns isolated nucleic acid molecules encoding the novel TIE ligand homologues NL2, NL3 and NL6 (FLS139), the proteins encoded by such nucleic acid molecules, as well as methods and means for making and using such nucleic acid and protein molecules.

Description

HIGH PERFORMANCE PROCESS FOR SULFUR RECOVERY STARTING FROM H2S CARRIER GAS CROSS REFERENCE WITH RELATED APPLICATION This patent application is a continuation in part of the United States patent application co dependent series no. 08 / 926,652, filed September 10, 1997, which is included herein by reference. BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention is based on the field of sulfur removal and recovery, and in particular on the treatment of gases rich in sulfur-containing products in the chemical process industry that contain hydrogen sulfide. 2. Description of the Prior Art Much of the natural gas produced in the United States has a hydrogen sulfide content exceeding 4 parts per million and is therefore classified as "rich in sulfur products". Because hydrogen sulfide is a hazardous environment, gas rich in sulfur-containing products is not considered acceptable for transport or use. Hydrogen sulfide levels are also a problem in the manufacture of fuels derived from petroleum, coal and lignite, whose sulfur content is converted to hydrogen sulfide during the conversion of these materials into gasoline, turbosines, refinery gas, gas coal, water gas and the like. In addition to the environmental hazard, hydrogen sulfide represents a loss in the sulfur value of the raw material, which is recovered when the elemental sulfur is of important use for the chemical industry. The traditional method to convert hydrogen sulfide into natural gases and gas plant effluents is the Claus process, where part of the hydrogen sulfide is burned in the air to form sulfur dioxide and water: 2 H2S + 3 02? 2 S02 + 2 H20 (A) and the sulfur dioxide thus produced goes into reaction with more hydrogen sulfide to form sulfur and additional water: 2 H2S + S02? 3 Sx + 2 H20 (B) x The symbol "x" in Reaction B is used to indicate that elemental sulfur exists in a mixture of molecular species that vary in the number of sulfur atoms per molecule. The furnace (Reaction A) in the Claus process is operated with a fuel rich mixture, converting only one third of H2S to S02. The fuel-rich atmosphere results in a partial conversion of hydrocarbons that are present in the H2S supply for such compounds as COS and CS, which reduce the production of elemental sulfur and are hazardous in themselves. For maximum sulfur recovery, precise control of stoichiometry is needed, and this becomes difficult especially when considerable amounts of C02 and other inerts are present. Part of Reaction B occurs in the furnace and the rest is conducted in a heterogeneous system wherein the reaction mixture is gas phase and makes contact with a solid catalyst of activated alumina of a kind well known to those skilled in the art. of the Claus process. With continuous use, the alumina catalyst becomes dirty and is otherwise deactivated over time. This requires the interruption in the operation of the plant, loss of process time and the cost of regeneration or replacement of the catalyst, together with the associated costs of labor. Another disadvantage of Reaction B is that the equilibrium is limited to temperatures higher than the sulfur spray point, and although it is carried out in two to four stages, the reaction leaves 2% to 5% of the H2S and the S02 without reaction. Each stage requires a separate condenser to remove the elemental sulfur, and these capacitors require a large area of heat exchange and reheat the gas leaving each condenser minus the last. In addition, the steam generated by each condenser in low pressure, limiting its usefulness. Additional costs are incurred when treating waste gas where the sulfur content must be reduced ten to twenty times. SUMMARY OF THE INVENTION It has now been found that virtually complete conversion of hydrogen sulfide to natural gas or mixtures of other gases to elemental sulfur can be achieved with the use of a single stage reaction between hydrogen sulfide and dioxide. of sulfur, so that reaction products other than elemental sulfur and water are not produced. The reaction 2 H2S + S02? 3 S + 2 H20 (I) is conducted with excess H2S in the liquid phase in the presence of a liquid phase Claus homogeneous catalyst, at a temperature above the melting point of the sulfur but low enough to maintain the reaction in the liquid phase, and upstream of the furnace where the H2S without reaction is burned to produce the S02 that is consumed in the reaction (I). The H2S that is burned in the furnace is the excess of H2S that passes without reacting through the reaction of the liquid phase, optionally complemented by H2S from a jet carrying H2S that bypasses the reactor of the reaction (I) . The S02 in the kiln combustion gas is recycled to the reaction reactor (I) either as a gas or dissolved in a solvent, and in any case it serves as the total feed stream of S02 for the reaction. In basic terms, the invention as shown in FIG. 1 is as follows: (a) In a first stage 1, a mixture with H2S content passes through a continuous flow catalytic reactor where the mixture makes contact with S02 according to the reaction 2 H2S + S02? 3 S + 2 H2S (I) using approximately 10% to 50% in excess of H2S. The H2S enters the reactor either as a gas or dissolved in an organic solvent; in most cases the H2S will enter as a gas. In the same way, S02 enters the reactor as gas or dissolved in an organic solvent. Regardless of the phases of the jets entering the reactor, the two reactants are dissolved in a liquid organic solvent flowing through the reactor, the solvent enters with either of the two jets of incoming H2S or S02 reagent dissolved in the solvent , or as a circulating jet recycled from the reactor outlet. The reaction causes a significant fraction of S02, preferably substantially all, to react. The term "an important fraction" is used in the present to indicate at least half and preferably 80-90% or more. The organic liquid solvent also contains a dissolved catalyst that promotes the reaction (I). The reaction produces elemental sulfur, which is recovered from the product mixture by phase separation. The reaction is conducted at a temperature above the melting point of sulfur and below the boiling point of the solvent, preferably below the temperature at which the sulfur is polymerized. (b) In a second stage, 2, the H2S, including the H2S that passed without reaction through the first stage, is burned with oxygen according to the reaction. 3 H2S + 3 02? 2 S02 + 2 H2S (II) to convert the H2S to S02. The hydrocarbons that may accompany the H2S are burned to C02 and H2S where the organic sulfur compounds that may be present additionally produce S02. (c) In a third stage, 3, the S02 produced in the second stage is recovered by absorption and returned to the reactor (the first stage). The S02 in the third stage can be recovered in the solvent used in the first stage, 1, with the catalyst of the first stage dissolved in the solvent. The solution containing both S02 and the catalyst can then be recycled in its entirety to the continuous flow reactor (the first stage) as the S02 is supplied to the reactor. Alternatively, the solvent used to recover S02 in the third stage, 3, can be kept separate from the solvent in the reactor of the first stage, 1, without the S02 therein and sent to the first stage, 1, as a gas. The absorption of the third stage leaves a waste gas that is substantially free of H2S and S02. The various additional stages of the ascending, intermediate and descending process of these three steps are included in any of several arrays of preferred embodiments of the invention to improve the flow and transfer of jets, separate phases and control the concentrations and velocities of flow, separate the water that forms in Reactions I and II and control the other parameters of the process such as temperature and pressure. These and other features, modalities and advantages of the invention will be better understood from the following description. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block flow diagram illustrating the three primary stages of the process of this invention. FIG. 2 is a process flow diagram illustrating an embodiment of the invention wherein the feed gas is a natural gas jet rich in high pressure sulfur products or another stream of H2S content having a relatively high content of H2S and a relatively low content of hydrocarbons with 5 or more carbon atoms. The S02 is fed to the reactor as a solution in an organic solvent that also contains a dissolved catalyst. FIG. 3 is a process flow diagram illustrating an embodiment of the invention wherein the feed gas is a gas jet containing H2S typical of an alkanolamine absorber / distiller operation that recovers H2S from a gas of process.

In the embodiment of FIG. 2, S02 is fed to the reactor as a solution in an organic solvent that also contains a dissolved catalyst. FIG. 4 is a process flow diagram illustrating another embodiment of the invention that reduces the amount of recycled water to the phase separator downstream of the reactor. FIG. 5 is a process flow diagram illustrating yet another embodiment of the invention, wherein the S02 absorbed from the kiln combustion gas is separated from the solvent before being fed to the reactor. FIG. 6 is a process flow diagram illustrating a further embodiment of the invention, similar to that of FIG. 5, except that in the reactor the flow of gases and liquids is countercurrent. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS With respect to FIG. 1, the continuous flow reactor 1 described above serves as the first stage. In this stage, the H2S makes contact with the S02 in the presence of an organic liquid that promotes the conversion of these reactants to elemental sulfur and water according to the reaction I. The reaction takes place in the liquid phase, and the liquid it contains a homogeneous liquid phase catalyst, that is, one that dissolves in the liquid reaction mixture. When the jet carrying H2S is fed to the reactor as a gas, the jet preferably contains at least about 20 mole percent H2S and preferably from about 25 mole percent to substantially 100 mole percent H2S. The concentration of H2S entering the reactor is not critical to this invention and may have a large range of variation, but is preferably greater than the concentration of H2S in a typical natural gas jet or process jet of a water treatment plant. fossil fuel. If desired, the concentration is increased rapidly by selectively absorbing the H2S from the gas jet in a solvent, then separating the H2S from the solvent. The solvent can be the same solvent used in the continuous flow reactor. Alternatively, a different solvent may be used in a separate flow circuit. If the solvent is extracted from the reactor, it may also contain water produced by the above Reaction I, and the distiller will preferably volatilize the water of the solvent together with the distillation of the H2S. The emerging gas jet will then contain both H2S and water vapor. In any case, in the preferred embodiments, the H2S-containing jet fed to the continuous flow reactor 1 will find itself partially or completely in the phase in the concentration ranges indicated above. The gas mixture with H2S content prior to concentration is typically a gas rich in sulfur products whose H2S content can vary greatly, from a low percentage of 0.01 mol to levels of 1.0 mol percent and more. In the embodiments where the S02 enters the continuous flow reactor as a liquid, it can present itself in liquid form dissolving in the solvent that is used in the S02 absorber (previously identified as the third stage) in a concentration of less about 1% by weight, preferably from about 1% to about 40% by weight, and even better from about 3% to about 10% by weight. Alternatively, it can be dissolved prior to or upon entering the reactor in a solvent that flows independently through the reactor. The solvents used in the practice of this invention preferably have a moderate to low viscosity, as well as a state chemically inert to the reactants, products or other components with which they come into contact. For any particular solvent, this will depend on the particular unit of the process where the solvent is used. The preferred solvents are those that rapidly absorb H2S and S02, which do not form an azeotrope with water, which are chemically inert to the reactants, liquid sulfur and water, and which have limited mutual solubility with liquid sulfur. Preferred solvents are those which are derived from ethylene oxide or propylene oxide by a ring-opening reaction with a coreactant having an active hydrogen, provided that the resulting solvent is inert both with respect to sulfur and to S02. Many of the polyglycol monoethers and many of the diets of both ethylene and propylene glycol satisfy these descriptions. When the reaction is carried out in these solvents, sulfur compounds of a higher oxidation state are not formed, and thus elemental sulfur and water are the only products of the reaction. Examples are glycols and glycol ethers derived from ethylene oxide or propylene oxide, in particular ethers of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol. Specific examples are the monomethyl, dimethyl, monoethyl and diethyl ethers of these glycols. Most preferred among these are the diethylene glycol monomethyl ether and the monomethyl and diethyl ethers of triethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol. The most favorite is diethylene glycol monomethyl ether (DGM). Additional solvents capable of use in this invention are various trialkyl and aryl amines such as triethylamine and methyldiethanolamine and quaternary ammonium salts of liquid alkyl and aryl. The primary and secondary amines react with the elemental sulfur and are therefore not suitable. As the catalyst for reaction (I), tertiary amines are preferred, in particular tertiary amines substituted with lower alkyl, tertiary amines substituted with lower alkyl and aryl and tertiary amines substituted with aryl, including those where the amine nitrogen is a aromatic ring atom. Examples of useful tertiary amines that do not contain an aromatic ring nitrogen are N, N-dimethylaniline, triethylamine, tri-n-butylamine and mixed trialkylamines. Preferred catalysts are those which contain an aromatic ring nitrogen which is not hindered spatially by substitutions at the carbon atoms adjacent to the ring nitrogen. Particularly preferred catalysts are pyridine and isoquinoline, optionally substituted at one or more sites other than the carbon atoms adjacent to the ring nitrogen with a polar group. Examples of suitable polar groups substituents are hydroxyl, hydroxyalkyl, acetamido, acetamidoalkyl, acetyl, acetylalkyl, acetyl-x ±, acetyloxyalkyl, alkoxy, alkoxyalkyl, amino, alkylamino and aminoalkyl groups. The "alkyl" portions of these terms refer to lower alkyl, ie Ci-Cß alkyl, with straight or branched chain, provided the alkyl group does not completely disguise the polar character of the substituent. Preferred alkyl groups are C1-C4, in particular methyl and ethyl. Particularly preferred substituents are hydroxyl, hydroxymethyl, acetamido, acetamidomethyl, acetyl, acetylmethyl, acetyloxy and acetyloxymethyl. The most preferred ring structure is pyridine and the most preferred catalyst is 3- (hydroxymethyl) pyridine (3-pyridyl carbinol). The concentration of the catalyst in the solvent is not critical to the invention and can vary greatly. For economic and effective results, a typical concentration range is from about 0.1% to about 1.0% by weight, although concentrations above and below this amount can also be used effectively. The H2S entering section 1 of the reactor will often contain small to moderate concentrations of other gases such as C02, hydrocarbons, mercaptans, COS and CS2. Said compounds are inert in the reaction of Step 1 and will pass through reactor 1 without change, together with the excess of H2S. When one or both of the reactant feed streams entering the reaction stage is gas, the flow through the reactor may be either parallel or countercurrent. For parallel flow, the reactor is preferably an inert packed column loose bed designed to increase the contact of solids and liquids with turbulence. Examples of column packing that can be used are Raschig rings, Lessing rings, Berl shoe, Intalox shoes, Tellerettes, Pall rings and various structured packing designs that are readily available in the industry. The countercurrent flow reactors are similar to those of conventional design. Columns packed as described above for parallel flow can also be used for countercurrent flow. Other alternatives, however, are plate columns with bubble bell plates, screen plate, valve plate and diffuser plates. The residence time inside the reactor is not critical and can vary a lot but it must be sufficient for the S02 to react to the extinction. In view of the excess H2S, this will typically be achieved with a gas phase residence time range of from about 0.5 seconds to about 30 seconds, preferably from about 1 second to about 20 seconds, better still from about 1 second to about 15 seconds In the particularly preferred practice of this invention, the gas phase residence time is from about 2 seconds to about 10 seconds. The temperature and pressure of the reaction are generally selected to produce elemental sulfur as a separate phase of light yellow liquid. This is usually obtained by conducting the reaction at a temperature between the sulfur melting point (119 ° C) and its polymerization temperature (approximately 155 ° C). A preferred temperature range is from about 125 ° C to about 145 ° C. It is then also preferable that at least some of the water produced by the reaction is volatilized in the reactor to leave it as part of the malodorous gas. However, it is possible to operate the reactor below the sulfur melting point if the forecast is taken to handle the solid, crystalline product while it is being formed. Therefore, in a broader sense, the reactor can be operated within a temperature range of from about 45 ° C to about 150 ° C. However, the preferred temperatures are those within the aforementioned range. The temperature is maintained in the desired range by allowing the water to evaporate from the solvent or by means of suitable indirect heat exchange. The means to obtain this will be easy to observe by the experts in reactor design. The furnace 2 described above as the second stage of the process of this invention burns the unreacted hydrogen sulphide (in excess) from the continuous flow reactor with an oxygen-containing gas. Air is the most convenient, but other gas mixtures containing oxygen can be used (in which essentially all other components thereof are inert) or oxygen itself. To prevent the formation of S03 and nitrogen oxides (N0X), or to minimize the formation of these gases, the furnace is preferably operated so that there is little or no 02 in the flue gas leaving the furnace. This can be carried out by combustion according to conditions ranging from stoichiometry to slightly rich in fuel, that is, the H2S entering the furnace must have a margin of approximately relative stoichiometry for the oxygen in the previous Reaction II , to approximately 5% excess. In certain embodiments of this invention, the furnace is operated with a slight excess of oxygen instead of H2S. Gaseous components of the H2S feed stream such as hydrocarbons, mercaptans, COS and CS2 are completely burned under these conditions. The compounds with sulfur content produce their sulfur as S02. When C02 is a component of the feed stream, it passes through the furnace unchanged and hinders combustion only if its concentration is excessive. The H2S feed stream for furnace 2 will include all of the gas with H2S which has omitted reaction step 1. When this is done, it is still preferable to keep excessive H2S in the reaction step 1, although perhaps less than when all The H2S feed stream for the process is directed to the reaction stage. In the processes that include H 2 S deviation, approximately up to 30%, or preferably approximately 10% to approximately 30%, of the H 2 S feed stream for the process can be diverted. Whether or not a H2S derivation is used, the total H2S feed stream for the process as a whole (including the bypass H2S if one is present) is preferably in an approximately 50% excess relative to the current of S02 feed for reaction stage 1, with reference to the stoichiometry of reaction (I). The absorber 3 of S02, the third stage of the process of the invention, recovers the S02 of the flue gas in a form in which it can be recycled, or prepared additionally for recycling, again for the reaction stage 1. The absorption solvent it can be the same solvent used in the reaction stage 1 and therefore be returned to the reactor as an S02 transporter. Alternatively, the absorption solvent may be part of a separate circuit from which the S02 is first distilled before being fed to the reactor. When the absorption solvent is used as a carrier of S02 to the reactor, the solvent will also contain the liquid phase catalyst for reaction (I). When the jet absorbing solvent of the product leaving the reaction stage 1 is recovered, it is preferably distilled from the net water added to the solvent in stage 1 and substantially all dissolved in H2S before the solvent enters the absorber . In the preferred solvents for this process, the solubility of S02 is very high. These solvents absorb substantially all of the S02 from the combustion gas. The S02 in the waste gas leaving the absorber can be reduced to 10-100 parts per million (ppm) by volume which is well below the current emission limits. The solubility of C02 in these solvents is relatively low and the amount of CO 2 absorbed from the combustion gas is negligible. The waste gas of the S02 absorber is thereby substantially free of H20 and S02. The term "substantially released" is used in this context to include the trace amounts of each gas, such as amounts in the range of about 10-100 ppm or less for S02 and about 0.01-1.0 ppm or less for H2S . FIGS. 2 through 6 are detailed process flow diagrams for particular sulfur recovery processes within the scope of the invention. FIG. 2 is a process flow diagram for a plant designed for a reaction using liquid phase S02 and a liquid phase catalyst, with a natural gas feed stream rich in sulfur products 11 in 1,000 pounds per absolute square inch (psia) (68 atmospheres) containing 2.7 mole percent H2S and 0.1 mole percent H20. The gas rich in sulfur products passes first through an upwardly flowing absorber 12, the absorber is a tower packed with gas and liquid countercurrent flow. The solvent 13 with the dissolved catalyst enters the upper part of the absorber 12 at about 40 ° C (104 ° F) at a rate of about 3 kg. per 100 moles of feed gas or approximately 1.5 times the minimum flow required for absorption of H2S in the feed gas. Using diethylene glycol monomethyl ether (DGM) as the solvent, the gas jet rising beyond the packed section of the absorber 12 (still inside the absorber) is balanced with water present in the incoming solvent jet 13 and contains about 10 ppm (by volume ) of DGM. In the portion 14 of the absorber above the compact bed, a small jet of water 15 is introduced to absorb the remaining solvent to avoid loss of solvent in the gas s eet 16 (without H2S) leaving the top of the absorber. The solvent rich in H2S leaving the absorber contains almost all the H2S and H20 of the feed stream of the gas rich in sulfur-containing products. The solvent rich in H2S passes through a valve 21 where its pressure is dropped close to the atmospheric value, then it is preheated in a heat exchanger 22 before entering the solvent distiller 23 as a side stream. Entering the top of the solvent distiller 23 is a wet solvent jet 24 which also contains a small amount of H2S. The wet solvent jet 24 is the liquid effluent from the continuous flow reactor 25 (corresponding to Step 1 of FIG.1 and discussed below), after the separation of the H2S without reaction, the liquid vapor and the liquid sulfur produced in reactor 25, the separation having been carried out in a gas-liquid-liquid separator 26 (discussed below). The wet solvent jet 24 contains the solvent and the catalyst used in that reactor plus the water and a small amount of dissolved H2S, the wet solvent having been separated from the sulfur in gas and liquid in the gas-liquid-liquid separator 26.

The solvent distiller 23 operates at a slightly higher than atmospheric pressure and is heated by a kettle 27. The lean solvent 28 that emerges as the distiller's seats is substantially free of H2S and completely free of S02, and contains about 1% of the solvent. water (by weight) at a temperature of approximately 170 ° C (338 ° F). The vapor jet 29 leaving the solvent distiller contains the H2S, water, hydrocarbons and other components that were absorbed from the feed gas rich in sulfur products 11, plus the water and H2S returned from the gas-liquid-liquid separator 26. This steam jet, which contains about 2.5 moles of water vapor per mole of H2S, is directed through a partial condenser 31 to the reactor 25. The heat input to the kettle 27 is approximately 102 kcal per mole of H2S in the reactor. gas feed. The distillation factor for water from the DGM solvent, KagUa V / L, is 7 or more. Only four theoretical stages are necessary to reduce the H2 O content of the solvent to 1% and distill 99.99% (all by weight) of the H2S of the solvent. The lean solvent 28 emerging from the solvent distiller's seat 23 is divided into two fractions, one is directed to the S02 absorber 35 (corresponding to Step 3 of FIG. 1 and discussed below) and the other 36 it is directed to the H 2 S absorber 12. This last fraction 36 heats the solvent rich in H 2 S 17 in the heat exchanger 22 between the H 2 S absorber 12 and the solvent distiller 23 and is then further cooled with cooling water at about 40 ° C (104 ° F) in a heat exchanger 37. The first fraction 34 passes through a heat exchanger 38 where it preheats the jet of liquid emerging from the gas-liquid-liquid separator 26 before the jet enters the distiller solvents 23. The solvent poor in this fraction is further cooled with cooling water to approximately 40 ° C (104 ° C) in a heat exchanger 39 prior to its entrance to the S02 absorber 35. The steam jet 29 (malodorous gas) from the solvent distiller 23 contains about 2.5 moles of H20 per mole of H2S. Approximately one third of the water vapor condenses in the partial condenser 31 and the entire jet, including both the condensate and the gas, enters the upper part of the reactor 25. Also in the upper part of the reactor is the solvent rich in S02 41 (plus the dissolved catalyst) at a temperature of about 45 ° C (113 ° F) and the two flow parallel downwardly through the packed bed 30. As an example, the flow velocity of the solvent 41 can be 0.33 kg per mol of H20 in the gas stream rich in sulfur products 11. The reactor itself can have an active volume measuring approximately 0.075 times the volumetric flow rate per hour of solvent, and can be packed with half an inch (1.3 cm) of Pall rings . The temperature near the point of entry into the reactor is approximately 115 ° C (239 ° F) and the temperature of the mixed phase product jet 42 leaving the reactor is controlled at 120-140 ° C. The jet of mixed phase product 42 is directed towards the gas-liquid-liquid separator 26, where (i) the liquid sulfur 43, (ii) the solvent containing the catalyst, water, H2S 44, and (iii) the Gas containing H2S and water 45 are separated into three separate jets. The gas stream containing H2S and water 45 is passed through a cold water condenser 46 to a gas-liquid separator 47. The liquid jet 48 extracted from the separator is divided into two jets 49, 50. One of these jets 49 is returned to the upper part of the gas-liquid-liquid separator 26 to absorb the additional solvent vapor and thus prevent loss of the solvent. This added water also serves to reduce the solubility of the liquid sulfur in the solvent in the separator 26. The water is then separated from the solvent in the solvent distiller 23. With the sulfur content thus reduced (or eliminated), the lean solvent 28 can be cooled to 40 ° C (104 ° F) by the heat exchangers shown, without depositing solid sulfur on the surfaces of the heat exchangers. It is currently believed that the amount of water required to achieve this result is approximately 7.5 moles / kg of DGM. This results in approximately 0.33 moles of water per mole of H2S in the feed gas rich in sulfur products 11. The second jet 50 is fed to a small distiller of H2S and water 51 where the H2S is extracted as a gas 52 from the water 53. The rest of water 53 represents the net flow of water absorbed from the feed gas plus the water that is formed by the reaction both in the reactor 25 and in the furnace 54 (discussed below). The thus extracted H2S 52 is passed back through the gas-liquid separator 47. The liquid sulfur jet 43 produced in the reactor 25 and separated in the gas-liquid separator 26 is fed to a dry steam distiller 61 for recover any H2S and solvent 62 present in the sulfur and return them to the gas-liquid-liquid separator 26. The amount of sulfur produced is 0.9999 + moles per mole of H2S in the gas stream rich in sulfur-containing products 11. The gas jet 63 leaving the gas-liquid separator 47 is fed directly to the furnace 54 (corresponding to Step 2 of FIG 1) where the gas jet is burned with atmospheric air 64. In the fuel-rich mixture of the furnace 54, H2S is converted to S02 and the sulfur content of mercaptans, COS and other sulfur-containing compounds are also converted to S02. Hydrocarbons and other organic substances are burned at C02 and H20. Due to the high concentration of S02 in the combustion gas, H2, CO, COS, CS2 or soot will not form. The combustion of H2S will produce 118 kcal / mol at 95% efficiency. The energy is gathered by generating boiler feed steam 65 which is fed through the furnace. The steam can be used in the reboiler 27 in the base of the distiller 23. The combustion of organic substances present in the malodorous distiller gas 45, which are transported through the gas separator, is added to the energy generated in the furnace. liquid 47 towards the furnace together with the H2S. The combustion gas 66 leaving the furnace contains one mole each of S02 and H2S and six moles of nitrogen gas per mole of H2S gas entering the furnace. The combustion gas 66 is directed to the S02 absorber 35, where it is absorbed in countercurrent flow by the lean solvent 34 (which is substantially free of H2S and completely free of S02). With DGM as a solvent, the heat temperatures of the S02 and H2S solution are approximately 9 kcal / mol and 10 kcal / mol, respectively, which would produce a temperature rise of about 32 ° C in the DGM for an output concentration of one mole of S02 per kg of DGM. The sensible heat of the kiln gas, together with the combustion water coming from any hydrocarbon, will also contribute to the rise in temperature. To control the temperature and minimize the net flow of solvent through the absorber, a quench jet 67 of the S02 carrier solvent 68 emerging from the bottom of the absorber, cooled 69 and recycled to the absorber is withdrawn. While in the H2S absorber, a small jet of water 71 is introduced into the upper part of the S02 absorber above the point of introduction of the lean solvent 34, to reduce the solvent content of the flue gas 72. FIG. 3 represents a variation of the process flow diagram of FIG. 2, designed for feed gases rich in sulfur products that are predominantly H2S. Such feed gases are typical of malodorous gas from an alkanolamine absorber / distiller (or activated potassium carbonate) operation used to remove H2S and other acid gases from a process gas jet, although the feed gas rich in H2S can also come from other sources. The feed gas can also contain C02, hydrocarbons, mercaptans, COS, etc., but the H2S fraction will typically exceed 50% and can approach 100%. All the components and flows in this example are the same as the corresponding parts of FIG. 2, except for the solvent distiller 81, which in this process serves only to separate the water and H2S dissolved in the solvent leaving the gas-liquid-liquid separator 26. The absorber / distiller mentioned in the previous paragraph is not shows in FIG. 3, but has conventional construction and operation. The amine solvent used in the absorber / distiller absorber portion is preferably an aqueous solution of an alkanolamine, a dialkanol amine or an alkali metal carbonate. Preferred among the alkanolamines and dialkanolamines are the (C? -C alkanol) amines and di- (C 1 -C 4 alkanol) -amines, examples of which are monoethanolamine, diethanolamine, methyldiethanolamine, diglycolamine, propanolamine and isopropanolamine. Preferred among the alkali metal carbonates is potassium carbonate. The H2S is then distilled from the solvent by conventional means. The H 2 S-rich feed stream 82 enters the continuous flow absorber / reactor 25 (corresponding to Step 1 of FIG 1) where it comes into contact in the parallel flow with a S02 84 solution containing a homogeneous catalyst for the Claus reaction of liquid phase between H2S and S02. The pressure in the absorber / reactor 25 is maintained from 1.5 to 2 absolute atmospheres. Any dissolved S02 that is deaerated at the reactor intake will be reabsorbed as the reaction progresses. The contact time in the absorber / reactor 25 is controlled to achieve full or substantially complete reaction of the S02 in the solution. The jet exiting the bottom 85 of the absorber / reactor 25 is a combination of gas and liquid phases that are separated in the gas-liquid-liquid separator 26. The gas phase flows through a packed section 86 in the top of the separator and is washed with water to remove the solvent vapor. The gas 88 exiting the steam-wash section is cooled 89 as necessary to condense the water 90, and the non-condensed gas 91 flows into the furnace 54. Returning to the gas-liquid-liquid separator 26, the more low of the two liquid phases 92 is liquid sulfur, which is decanted from the light liquid solvent phase 93. Water enters the gas-liquid-liquid separator 26 from two sources - one is the product jet 85 of the absorber / reactor 25 , and the other is the condensate 87 that condenses from the general jet of the gas-liquid-liquid separator. The water added in this way to the separator helps to remove most of the dissolved sulfur from the solvent and the separated sulfur joins the remainder of the sulfur jet 94 formed in the reactor. The wet solvent 101 emerging from the gas-liquid-liquid separator 26 is fed directly to the solvent distiller 81 where the H2S and most of the water are removed from the solvent. The solvent 102 exiting the distiller 81 is then cooled 103 and directed to the absorber 35. Because the solvent content at this point is virtually zero, the solvent is a very effective sorbent for the S02 in the absorber 35. The oven 54 operates with slightly more than stoichiometric air 111 to generate S02 which is then absorbed by the lean solvent 102 in the S02 161 absorber while preventing the formation of S03. Sulfur-containing compounds such as COS, mercaptans and others are also burned in furnace 54 to recover their sulfur content (as S02) and heating value without risk of removing said compounds into the atmosphere. Furnace 54 typically generates a burned gas containing 10% to 20% S02 by volume. This gas is cooled to approximately 150 ° C in a recovery boiler 112 and fed to the absorber of S02 35. The solution of S02 113 leaving the absorber is heated and returned to the absorber / reactor 35. A characteristic of this process is that the steam required to recover the water of the wet solvent entering the distiller exceeds that produced in the recovery boiler. Another variation is shown in FIG. 4. The H2S-rich feed jet 171 enters the continuous flow reactor / absorber 172 (corresponding to Step 1 of FIG.1) where it makes contact in the parallel flow with a solution of S02 173 which contains a homogeneous catalyst for the Claus reaction of liquid phase between H2S and S02, at a pressure of 1.5 to 2 absolute atmospheres. The contact time in the absorber / reactor is sufficient to achieve complete or substantially complete reaction of S02. The jet exiting the bottom 174 of the absorber / reactor 172 contains both gas and liquid phases that are separated in a gas-liquid-liquid separator 175. The gas phase flows through a packed section 176 at the top of the separator and it is washed with water 177 to remove the solvent vapor. The gas 178 exiting the steam-wash section (packed bed) is cooled 179 as necessary to condense the water, which is separated from the non-condensed gas in a gas-liquid separator 181 and returns by circulation to the gas-liquid section. compact bed 176. The uncondensed gas 182 flows into the furnace and into the recovery boiler 183. In the gas-liquid-liquid separator 175, the liquid sulfur 185 forms the lower phase of the two liquid phases and is decanted from the solvent 184. which forms the upper phase of the two liquid phases. The solvent phase 184 is fed directly to the solvent distiller 191 where the H2S dissolved in the solvent is steam distillation 190 and removed as general 192. The solvent 193 extracted from the bottom of the distiller flows into a vacuum crystallizer 194, where a large part The remaining water is vigorously boiled to cool the solvent to the temperature required to operate the S02 195 absorber (35 ° C to 45 ° C), which is essentially the same as the corresponding unit of the process flow diagram of FIG. 2. The residual mixture in the crystallizer is pumped to a compensation chamber 196 where the sulfur crystals that form in the crystallizer can settle to form a more concentrated mixture 197 that is pumped back to the gas-liquid-liquid separator 175 In the gas-liquid-liquid separator 175, the crystals in the concentrated mixture are fused and bound to the liquid sulfur product. The clarified solvent 198 which is poor in relation to the H2S and S02 is extracted from the compensation chamber 196 and passed to the S02 195 absorber. This process configuration only requires approximately 20% steam output from the recovery boiler for its operation. The process configuration of FIG. 5 presents another example. The basic elements of the invention are present as a packed reactor column 201 corresponding to Step 1 of FIG. 1, a recovery furnace and boiler 202 corresponding to Step 2, and an S02 203 absorber corresponding to Step 3. Both the incoming H2S rich jet 204 for the reactor column 201 and the incoming rich SO2 jet. 205 are in the gas phase. In the reactor column, the two jets are mixed with an organic solvent 206 containing a dissolved homogeneous catalyst and the Claus reaction is conducted in the liquid phase in the parallel flow of both gases and liquids. The reactor column 201 contains packing that is divided into sections 207, 208, 209, 210, 211, each section packed providing vigorous combination of the gas and liquid phases. The cooling is performed between each adjacent pair of section by means of injection of water 212 which evaporates in the column. Another cooling medium, such as the various methods of indirect heat exchange, can be replaced by water. At the bottom of the column, the mixture of the product 213 containing both gas and liquid flows to the gas-liquid-liquid separator 214 where the gas and the two liquid phases (solvent 206 and liquid sulfur 215) are separated as in the configurations of process of the previous figures. The solvent 206 is recycled to the reactor intake. The components of the process configuration of FIG. 5 which are not described in the previous paragraph, also appear in the process configuration of FIG. 6 The description of these components that appears in the following comment of FIG. 6 applies both to FIG. 5 as to 6. The parallel flow column 201 of FIG. 5 is replaced by a countercurrent flow column 221 in the process configuration of FIG. 6. This countercurrent flow column 221 contains bubble bell plates 222, which allow the residence time of the gas and liquids to be controlled independently. The individual plates also allow the depths of liquid sulfur and solvent to be adjusted independently. Countercurrent flow is achieved by introducing the gas rich in H2S 223 and gaseous S02 224 at the bottom of column 221 for upflow while organic solvent 225 with dissolved catalyst is introduced at the top of the descending gravity flow. From the feed stream of the H 2 S-rich gas 226 entering the system, a portion 227 that reaches up to 30% of the total inlet 226 is diverted to bypass the reactor column 221 and flow directly into the furnace 228. The flows of gas rich in H2S 223 and gas with S02 224 content with controlled so that approximately 80% to 90% of H2S and all or virtually all of S02 react in the column. To maintain an economically effective reaction ratio, a high concentration of H2S must be maintained in the gas phase while proceeding with the reaction. If the gas feed stream rich in H2S contains a large amount of other gases, the relative feed stream ratios of H2S and S02 in the feed streams for the column are preferably selected so as to result in the input of a relatively large excess of H2S to the column. On the contrary, if the gas supply stream rich in H2S is almost pure H2S, a relatively small amount of H2S in excess will suffice to maintain the reaction rate. In the configuration of FIG. 6, the jet of S02 224 is introduced to the column 221 at a point lower than the inlet for the gas rich in H2S 223. Even though only part of the S02 jet is introduced at this point, this causes the liquid sulfur 229 produced in the column, come in contact with a solution rich in S02 before leaving the column. This removes any undissolved H2S from the liquid sulfur, a favorable result since the H2S has significant solubility in liquid sulfur and is toxic, and therefore has an undesirable impurity. In addition, a small stream of distillation steam 230 can be introduced below the inlet of S02 to distill S02 from both sulfur 229 and solvent 225. The reaction occurring in column 221 is a liquid phase reaction between H2S and S02, being both absorbed from the gas phase by the circulating solvent 225 and introduced at relative speeds to place the H2S in an excess of stoichiometry. At the temperature of the reaction, H2S and S02 have similar solubilities in glycols and glycol ethers. The use of excess H2S facilitates the substantially complete reaction of S02 maintaining a relatively high concentration of H2S concentration in the solvent. The steam jet 241 leaving the column 225 consists mainly of water and unreacted H2S together with other components that were present in the original H2S feed stream 226. The steam 241 is cooled 242, and the condensed water 245 is separated of the non-condensable products 244 in a gas-liquid separator 243. The non-condensable products 244 are sent to the furnace 228, and part of the condensate 245 is returned to the reactor column 221 as a refrigerant. An additional source of coolant, although not shown in the drawing, is the condensed water of the S02-rich jet 246 leaving the S02 distiller 247. The remainder 248 of the condensate 245 of the reactor steam stream is saturated with H2S. This portion of the condensate is sent to a water distiller rich in sulfur-containing products 249 to remove the H2S. Part of the waste product 250 of the water distiller rich in sulfur products can be used for wash water 251 in the upper part of the S02 distiller and the upper part 253 in the absorber 254. The non-condensable products 244 leaving the reactor column 221 are combine with portion 227 of the H2S rich gas feed stream that has deviated from the reactor column, and the combined jet that flows to furnace 228 where it is burned with air. The amount of air used in the furnace is preferably slightly greater than the proportion of stoichiometry required for complete combustion of H2S, hydrocarbons and other fuels. However, the amount of excess air remains low enough to prevent the formation of S03. Furnace 228 typically generates a burned gas containing S02 in an amount of 10% by volume or more. This gas will be cooled in the recovery boiler 255 and then fed to the S02 254 absorber. The C02 excess is a minor concern in the furnace than it is in a conventional Claus furnace in terms of maintaining a stable level of combustion in the furnace. the oven. In the conventional Claus process, only one third of the H2S is burned in the furnace, and the furnace gas is thereby diluted with a large amount of excess H2S that is not present in the process described in this invention. If an excessive amount of C02 or other inert gas is present in the furnace feed stream, a gaseous fuel such as natural gas can be added to ensure stable combustion. The present invention also avoids the problems that soot creates in conventional Claus reactors. In the conventional process, soot, which results from the partial combustion of organic compounds in a fuel-rich mixture in the furnace, enters the gas phase Claus reactor and fouls the solid phase catalyst (as well as the sulfur product). ). This is avoided in this invention by conducting the Claus reaction in the upstream liquid phase of the furnace. The process described in FIG. 7 offers the additional advantage that it allows the use of a solvent in the absorber 254 and the distiller 247 and another solvent in the reactor column 221. The two solvents can thus be chosen independently, each selected as the most convenient for the particular function for which it serves in the individual units. All units and operations of units, including distillers, absorbers, packed columns, separators, heat exchangers and associated pumps and valves, are conventionally constructed from conventional materials whose choice will be readily appreciated by expert chemical process engineers, particularly one with experience in the treatment of gas jets rich in sulfur products. The foregoing is offered primarily for purposes of illustration. Those skilled in the art will readily be able to see that the process flow schemes, the relative flow rates, the jet compositions, operating conditions and other process parameters described herein may be modified or additionally substituted in various ways without departing from the spirit and scope of the invention.

Claims (18)

1. A process for treating a jet that carries H2S to convert the H2S that is in it into elemental sulfur, the process comprises: (a) supplying the jet carrying H2S to a continuous flow reactor and contacting the jet carrying H2S in the reactor with a jet carrying S02 and a liquid organic solvent under the following conditions: (i) the liquid organic solvent contains a homogeneous catalyst that promotes the liquid phase reaction. 2 H2S + S02? 3 S + 2 H20, (I) (ii) the temperature in the reactor is maintained above the melting point and below the boiling point of the solvent, and (iii) the H2S and S02 jets are supplied at relative feed rates so that the H2S is supplied in the same amount as the S02 according to the reaction (I), to substantially convert all the S02 into liquid elemental sulfur and produce a reactor discharge containing the liquid elemental sulfur and the H2S without reaction; (b) burn the H2S without reaction with a carrier gas of 02 according to the reaction 3 H2S + 3 02? 2 S02 + 2 H20 (II) to convert the H2S without reaction to S02 and produce a combustion gas having S02 and H2S; and (c) passing the combustion gas through an S02 absorber to recover substantially all of the S02 from the combustion gas, thereby leaving a residual gas substantially free of H2S and S02 and recycling all of the S02 thus recovered to the gas. Continuous flow reactor according to the entire S02 is fed to it.

2. A process according to claim 1 wherein the temperature in (a) (ii) is maintained between 119 ° C and 155 ° C.

3. A process according to claim 1 wherein the temperature in (a) (ii) is maintained between 125 ° C and 145 ° C.

4. A process according to claim 1 wherein the jet carrying H2S is a gas jet, the jet carrying S02 is a S02 in liquid phase dissolved in the solvent and the catalyst is also dissolved in the solvent.

A process according to claim 1 wherein both the jet carrying H2S and the jet carrying S02 are gas jets and both are absorbed into the reactor by the solvent, the solvent containing the catalyst dissolved therein.

6. A process according to claim 5 wherein the reactor is a column-type liquid gas contactor and wherein the gas jets flow in parallel with the solvent and liquid elemental sulfur.

7. A process according to claim 5 wherein the reactor is a column-type gas-liquid contactor and wherein the gas jets flow in parallel with the solvent and the liquid elemental sulfur.

8. A process according to claim 5 further comprising: (d) passing the reactor discharge through a separator to separate into separate jets a liquid sulfur phase, an organic liquid phase and a gas phase; (e) extraction of H2S from the organic liquid phase to a steam distiller leaving a residual distiller jet of organic solvent liquids substantially free of H2S, water and sulfur; (f) vigorously boiling the residual jet of the liquid distiller in a vacuum crystallizer to evaporate a substantial amount of water from the residual jet of liquid distiller and precipitate the sulfur therefrom, thereby forming a mixture of crystalline sulfur; (g) allowing the crystalline sulfur to settle in the mixture to form a concentrated mixture and a clarified solvent; and (h) feeding the clarified solvent in the S02 absorber and the concentrated mixture to the separator in step (d).

9. A process according to claim 1 further comprising supplying an additional stream of H2S carrier gas to the step (b) that has not passed through the continuous flow reactor of step (a) in combination with the H2S without reaction of the discharge of the reactor, the H2S having in the additional stream of gas with H2S an amount of approximately 10% to approximately 30% of the total of H2S fed in the process, the total of H2S being fed to the process approximately 50% more in relation to the SO2 fed to the continuous flow reactor according to the reaction (I).

10. A process according to claim 1 further comprising contacting the liquid elemental sulfur formed in step (a) with liquid phase S02 to remove the dissolved H2S from the liquid elemental sulfur.

11. A process according to claim 7 further comprising introducing the jet carrying S02 into the column-type gas-liquid contactor at a location below the introduction site of the H2S-carrying jet, both for countercurrent upflow to the liquids of downward flow in it, to remove dissolved H2S from liquid elemental sulfur before removing it from the contactor.

12. A process according to claim 1 wherein the solvent selected from the group consisting of ethers of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol.

A process according to claim 1 wherein the solvent is an element selected from the group consisting of monomethyl, dimethyl, monoethyl and diethyl ethers of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and tetrapropylene glycol.

A process according to claim 1 wherein the solvent is an element selected from the group consisting of diethylene glycol monomethyl and dimethyl ethers, triethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol.

15. A process according to claim 1 wherein the homogeneous catalyst is an element selected from the group consisting of pyridine and isoquinoline, optionally substituted at one or more sites that are not carbon atoms adjacent to the ring nitrogen with a polar group which is an element selected from the group consisting of hydroxyl, hydroxyalkyl, acetamido, acetamidoalkyl, acetyl, acetylalkyl, acetyloxy, acetyloxyalkyl, alkoxy, alkoxyalkyl, amino, alkylamino and aminoalkyl.

16. A process according to claim 1 wherein the homogeneous catalyst is an element selected from the group consisting of pyridine and isoquinoline, substituted at a site that is not a carbon atom adjacent to the ring nitrogen with an element selected from the group which consists of hydroxyl, hydroxymethyl, acetamido, acetamidomethyl, acetyl, acetylmethyl, acetyloxy, acetyloxymethyl.

17. A process according to claim 1 wherein the homogeneous catalyst is pyridine substituted at one site which is not a carbon atom adjacent to the ring nitrogen with an element selected from the group consisting of hydroxymethyl, acetamido, acetamidomethyl, acetyl, acetylmethyl, acetyloxy and acetyloxymethyl.

18. A process according to claim 1 wherein the homogeneous catalyst is 3- (hydroxymethyl) pyridine.