DD275814A5 - METHOD FOR REGENERATING A CARBON-STABLE ADSORB LOADED WITH SULFUR ACID AND WATER - Google Patents

Abstract

The invention includes a process for regenerating a carbonic acid adsorbent loaded with sulfuric acid and water. According to the present invention, a carbonaceous adsorbent loaded with sulfuric acid and water is regenerated with sulfur-containing reducing gas. The adsorbent to be regenerated passes through a drying zone, a reduction zone, a desorption zone and finally a cooling zone. The lower portion of the drying zone is supplied with reducing gas having inlet temperatures of about 250 to 400 ° C, wherein the adsorbent is heated to 80 to 150C. The reducing gas flowing up in the drying zone is drawn off at the upper end, cooled and at least partly directed into the cooling zone. Part of the reducing gas flows from top to bottom through the reduction zone. The H2SO4 loading of the adsorbent is completely converted to elemental sulfur. At temperatures of 400 to 650C, reducing gas flows from below into the desorption zone, mixes with the gas coming out of the cooling zone and removes the sulfur from the adsorbent by desorption and conversion. At the transition between the reduction and the desorption zone, the reducing gas is withdrawn and cooled to separate elemental sulfur. After renewed heating, a first portion of the reducing gas is introduced between the drying and reduction zones and the remainder of the heated reducing gas is passed to the lower zone of the desorption zone. figure

Description

Object of the invention

The object of the invention is to provide an improved process for regenerating a carbonaceous adsorbent loaded with sulfuric acid and water which is high-acting, flexible and economical.

Explanation of the essence of the invention

The invention has for its object to find a new technology for an improved, effective, flexible and economical Regenerierverfahren.

According to the invention Verfahron in such a way that the loaded adsorbent first wanders through a Trocknungszono whose height is 5 to 30% of the height of the bed in the regenerator, that heated the cooled, freed from auskondensiertem elementary sulfur reducing gas, a partial flow of the heated reducing gas with entry Introduces' Hstemperaturon of about 250 ° C to 400 ⁰ C in the range between the drying and reduction zone and that the remainder of the heated reducing gas with inlet temperatures of 40O ⁰ C to 650 ⁰ C of the desorption zone, that the adsorbent in the drying zone by Upwardly flowing Reduktionsges heated to temperatures of 8O ⁰ C to 150 ° C, partially or completely dried and then the adsorbent leaning in the reduction zone, that men from the upper end of the drying zone, a portion of the reducing gas with temperatures of 90 ⁰ C to 160 ⁰ C. and virtually free of elemental sulfur, in a condensate Cools cooler, condensed water vapor and removed and cooled, coming from the condenser reducing gas passes into the cooling zone. As carbonaceous adsorbents come z.tt. Activated carbon, activated coke or carbon coke in question.

Already in the drying zone, the reduction of the sulfuric acid by the HjS-haltlge reducing gas begins according to the reaction equation

H ₂ SO ₄ + 3H ₂ S - * 4S + 4H ₂ O.

The HjS-containing reducing gas is produced in the desorption zone by feeding with hydrogen, which is reacted with a portion of the sulfur loading of the adsorbent at temperatures of about 30O ⁰ C to fJOO ° C. For this production of H ₂ S, about 75% of the total elemental sulfur formed is reacted with hydrogen. If, instead of hydrogen, hydrocarbons (for example CH ₄ ) are passed into the desorption zone, then the sulfur and, if necessary, water vapor will react in accordance with the equations

4S + CH ₄ - * 2HjS + CS, or

4 S + CH ₄ + H ₁ O -> COS + 3H ₇ S

around. CS ₂ and COS are also able to form elemental sulfur with H ₂ SO ₄ in the reductone zone, as already described in the

DE-OS 3407884 is described. In the following explanations, it is assumed that the reducing gas

by introducing hydrogen into the desorption zone.

To optimize the gas composition to mix a partial flow of the coming from the condenser, grooved Reduction gas to the withdrawn reduction and desorption zone reducing gas. This will before allom the Flexibility of the procedure improved. Embodiments of the method will be explained with the aid of the drawing. In this case, instead of "carbonaceous Adsorbent "for the sake of simplicity" activated carbon "said. The enclosed drawing shows:

a schematic representation of an apparatus for carrying out the method according to the invention.

Hot flue gas is introduced into the line, it comes, for example, from a power plant and usually has temperaures in the range of about 13O ⁰ C to 1QO ⁰ C, it contains water vapor and more oxygen, as stöchlorrv table for converting SO ₂ with H ₂ O to H ₂ SO _{4 is} necessary. Under canning of water from the line 2 takes place in elno, ι Einspritz'.übler 3, the cooling of the flue gas to temperatures in the range of about 5O ⁰ C to 8O ⁰ C, while the relative water vapor saturation of the flue gas to 35 to 90% and preferably 45 to 60% set. This relatively katte flue gas is fed to the adsorber 5 in the line 4. The adsorber 5 contains zv / ischen two gas-permeable, jalousleavtigen walls 5 a and Bb a slowly moving downwards bed bulk granular activated carbon. The grain size of Ak'.ivkohlf / is in the range of about 3 to 15mm. Regenerated activated carbon comes from the feed 8, fresh activated carbon, as far as β! required, is introduced by the line 8a.

The flue gas which is largely freed from SO] flows out through the chimney 'J. If necessary, in the entschwjfolndon or in deshuffled flue gas a per se known means for the removal of nitrogen oxides can be switched on. Activated charcoal which is used with sulfuric acid and water is supplied to a column-shaped regenerator 12 via a draw-off device 10 and an elevating device 11. In the Rogonorator 12, the activated carbon also forms a bed which moves slowly downwards and flows through regenerating gas wildly. Dor Regenerator 12 is', in the drawing * chastnically in longitudinal section dargo (great, as well as the Adsorbor 5.

First, the activated carbon passes into drying zone 15, which is fed with reducing gas from line 16 to the lower zone. The reducing gas enters the Rogonorator 12 by means of the ring line 17 and a plurality of openings 20 at temperatures of approximately 260 ° C. to 400 ° C. Part of the reducing gas flows in drying zone 1 δ in countercurrent to

loaded activated carbon upwards, wherein the water is partially or completely removed from the activated carbon.

At the same time, the elemental sulfur contained in the gas as an aerosol is deposited on the activated carbon. Because the reducing gas H ₂ S contains, a certain part of the H ₂ SO ₄ charge of the activated carbon is already reduced here. In the drying zone 15 prevail maximum temperatures of 80 ⁰ C to 150 ⁰ C and preferably 100 to 120 ° C. Oa the gas

From the line 16 when entering the regenerator 12 meets already preheated activated carbon is einu shock-like

Heating them avoided. Advantageous welse arise by avoiding the contact of reducing gas containing Aerosolschwofel with cold Activated carbon or cold apparatus parts no sulfur caking, which otherwise, · blocking the moving bed or too

could cause other blockages. The reducing gas can therefore only in Gegensirom and not in DC with the

Activated carbon are passed through the drying zone 15. The reducing gas flowing upwards in the drying zone 15 is passed through the outlets at the upper end of the drying zone

18 and withdrawn the ring line 21 by means of a blower 22 and first led in the line 23 to a condenser 24. In which condenses water vapor, clementar sulfur is not contained in gas of line 23. The height of the drying zone 15 is 5 to 30% and preferably 10 to 20% of the height of the bed in the regenerator 12. The height of the

Drying zone 15 is dimensioned so that the adsorbed water is desorbed to the desired extent. Aqueous condensate leaves the condenser 24 in the line 25, a downstream droplet 26, the

separated water dissipates through the line 27, ensures further drainage of the withdrawn gas, as it flows in the line 28.

The remaining, H ₂ S-containing reducing gas entering the regenerator 12 through the openings 20, is down through a Reductor zone 30 sucked. In zone 30 at temperatures of 150 ° C to 300 ° C, the H ₂ SCV loading of the activated carbon

completely reduced to elementary crumbs. This state is reached at the latest when the activated carbon, the outlets 31 at the top? reach the desorption zone 32! Has. From top to bottom sucked by a blower 34 reducing gas passes übei dia outlets 31, the loop 35 and the line 36 to a condenser 37, in which sulfur vapor is condensed. Liquid elemental sulfur flows off in the line 38, a portion of the aerosol sulfur is deposited in the droplet 39 and discharged in the line 40. Cooled reducing gas with temperatures below 100 ⁰ C is introduced in the line 42 and the gas 36 is admixed to the line.

The reducing gas sucked in by the blower 34 in the line 41 still contains small amounts of sulfur in its fine distribution. On Partial stream of G.tses, which has about temperatures of 120 ⁰ C to 150 ⁰ C, is in line 43 with the control valve 44th

diverted. The main part of the gas passes to a heater 45 where it is heated to temperatures of about 400 ° C to 65O ⁰ C. A first partial flow of the hot reducing gas from the heater 45 is mixed via the line 46 to the relatively cold gas of the line 43 and generated to the reducing gas, which is guided in the conduit 16 to the drying zone IE. The

Rest of the hot reducing gas is in the conduit 50 through the control valve 49 to the lower Boreich the Dasorptionszone 32nd

fed.

The cooling zone 51 is sensed by the line 52 hydrogen and cooled by the Loitung 53 with control valve 54 Reduction gas to. This cooled Reduktioi «gas is sucked on the line 28 and the control valve 28a from the blower 22

and pressed via the line 2.9 in the lines 42 and 53. In the lower region of the desorption zone 32 thus occurs from the

Cooling zone 51 coming, hydrogen-containing regeneration gas, wherein the hydrogen with a portion of the Sulfur loading of the activated carbon to H ₂ S converts. In the upper part of the desorption zone 32, where temperatures of about 300 ⁰ C.

to 500 "C, this conversion is completed by consumption of hydrogen, so that there is a part of the

Sulfurischadung discharged in vapor form with the reducing gas and via the line 36 to the sulfur condenser 37th

to be led.

The freed from the loading, cooled activated carbon passes through a trigger device 55 on the transport path 56 to Reuse back to the inlet 8. Ausführungsbelsplel The invention will be explained in more detail below by way of example. The example, whose data is partly calculated, is based on the desulphurisation of 500000m ¹ flue gas per hour Activated carbon as adsorption catalyst. (All gas quantities given in rn ³ have already been converted to Nm ^3. ) These Flue gas is produced by a coal-fired power plant with an electrical output of 150MW / h. Per

m ³ , the flue gas contains 3300 mg SO ₂ , which are separated up to a maximum of 200 mg. This results in a

Sulfur recovery of 775 kg / h. The further explanation of the example takes place with the aid of the process control shown in the drawing. Through the inlet

are the adsorber 5 hourly 8t regenerated or fresh activated carbon supplied. The same amount is given to the regenerator 12, wherein the activated carbon with 2400kg H ₂ SO ₄ and 2400kg water is loaded.

The drying of the loaded activated carbon and the reduction of the sulfuric acid require per hour 36000m ^{3 of} reducing gas,

which is introduced through the line 16 with 300 ⁰ C. The gas heats the activated carbon in the drying zone 15 to at least 8O ⁰ C to 150 ° C, while the gas is freed from his Höhnlt of aerosol Schwofel. At the upper end of the drying zone 15 is withdrawn via line 23 3COOOmVh reducing gas, which after cooling to 4O ⁰ C and dewatering in an amount of

700OmVh übor the line 53 of the cooling zone 61 is supplied, the rest passes through the line 42 to Leitunp 36. About the

Radiator 24 and separator 26 exits the regeneration system 4000kg / h aqueous condensate. Through the reduction zone 30 6000m ^{3 of} reducing gas flow per hour and heat the activated carbon to at least 200 ⁰ C. In the case of oil from 160 OmVh H ₁ S the oil is completely discharged to about 3100 kg / h elemntar sulfur

implemented. 75% diones elemental sulfur has been in the Dosorptionszone 32 for the development of H ₂ S by reaction with

160OmVh of hydrogen consumed. The hydrogen is introduced via the line 52 and the cooling zone 51. The remaining load at Elementarechwefet wire 'desorbed. For this purpose, one passes per hour 26000 m ^{3 of} reducing gas at about 500 ⁰ C through the line 50 in the desorption zone 32nd

The desorbed elemental sulfur is vaporous and contained as an aerosol in the withdrawn via line 36 from the regenerator 12 reducing gas. The gas is cooled in the condenser 37 to about 125 ⁰ C. The thereby condensed sulfur is withdrawn liquid in a total amount of 775kg / h from the condenser 37 and the separator 39 via the lines 38 and 40. Its quality corresponds to that of Claus sulfur.

Claims (3)

1. A process for regenerating a loaded with sulfuric acid and water, coming from the desulfurization of flue gas carbonaceous adsorbent in a columnar regenerator, the loaded adsorbent from top to bottom as a bed, wherein the sulfuric acid with sulfur-containing reducing gas (H ₂ S and / or CS ₂ and / or COS) reacted at temperatures of 15O ⁰ C to 300 ⁰ C in a reduction zone to clementarschwefel and the elemental sulfur in a desorption zone at temperatures from 300 ⁰ C to 600 ° C partially reacted with hydrogen to hydrogen sulfide and the rest with reducing gas is removed from the adsorbent, wherein elementary sulfur-containing reducing gas is withdrawn from the region between the upper end of the desorption zone and the lower end of the reduction zone, cooled, condensed elementary sulfur and derived, and wherein the adsorbent substantially freed from the loading prior to reuse through a cooling zone leads, characterized in that the loaded adsorbent first passes through a drying zone (15) whose height is 5 to 30% of the height of the bed in the regenerator (12) that one heats the cooled, freed from condensed elemental reducing gas, a partial flow of the heated reducing gases with inlet temperatures of about 25O ⁰ C to 400'C in the area between the drying and reduction zone (15; 30) and in that the remainder of the heated reducing gas with inlet temperatures of 400 ⁰ C to 650 ° C of the desorption zone (32) feeds that the adsorbent in the drying zone (15) by upwardly flowing reducing gas to temperatures of 8O ⁰ C to 15O ⁰ C heated, partially or completely dried and then the adsorbent in the reduction zone (30) passes, that from the upper end of the drying zone (15) a portion of the reducing gas at temperatures of 9O ⁰ C to 16O ⁰ C and virtually free of elemental sulfur cools, in a condenser (24) cools, condensed water vapor and removed and cooled, from the condenser (24) coming reducing gas in the cooling zone (51) passes. 2. The method according to claim 1, characterized in that one mixes a variable partial flow of the condenser (24) coming, cooled reducing gas to the metered between the reduction zone (32; 30) deducted reducing gas. 3. The method according to claim 1 or 2, characterized in that the height of the drying zone is 10 to 20% of the height of the bed in the regenerator (12). For this 1 page drawing Field of application of the invention The invention relates to a process for the regeneration of a sulfuric acid and water-laden, from desulphurisation of flue gas coming Kreslcnstciifioltigcnc adsorbent in a columnar regenerator, the loaded adsorbent from top to bottom as a bed, wherein the sulfuric acid with sulfur-containing reducing gas (H] S and / or CS ₂ and / or COS) reacted at temperatures of 15O ⁰ C to 300 "C in a Roduktionszono to elemental sulfur and the elemental sulfur in a desorption zone at temperatures of 300" C to 600 "C partially reacted with hydrogen to hydrogen sulfide and the rest is removed from the adsorbent with reducing gas, wherein elementary sulfur-containing reducing gas from the Boreich between the upper end of the desorption zone and the lower end of the reduction zone is withdrawn, cooled, condensed elementary sulfur and derived, and wherein the largely freed from the charge adsorbent before reuse leads a cooling zone. Characteristic of the known state of the art Similar ancestors are described in DE-OS 3407884 and corresponding EP application published under number 0158749. The bokannten method works with two interconnected Roduktionszonen and a separate Kühlgaskrelslauf. A similar process is also described in the European patent application No. 0230058, which deals with the removal of nitrogen oxides and sulfur oloxide from a flue gas. The nitrogen oxides and part of them have been bound to a regalizable AI ₂ 0, catalytic jet, while the residual sulfur oxide is removed by activated charcoal. The HjS-roicho gas produced upon regeneration of the activated carbon is withdrawn and used to recover the charged alumina aluminum oxide.