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Sept. 3, 1946. ' A. c. MQHR ' 2,406,890 PRODUCTION OF SULPHUR DIOXIDE Filèd Feb. `1. _1945 QN bm. Nm. Patented Sept. 3, 1946 " 2,406,390 UNITED STATES VPATENT orifice 1 « ì .2,406,890~ PRODUCTION oF sULPrrUR nloxmn Albert c. Mohr, Arcadis, cam., assigner, by . mesne assignments, to Chemical Construction Corporation, New Yorki N. Y., a corporation of‘ Delaware ` A Application February 1, Y1943, Serial No. £114,343 .è claims. (ci. zza-_177) , . 1 \ i This invention relates to the recovery of the sulphur values present in the sludge or sulphuric acid residue resulting from the condensation of olelins with paraiiins in the presence of sulphuric acid. This condensation is usually termed alky1~ ation and the sulphuric acid body‘removed is usually termed alkylation sludge. It will be so referred to here. l2 , l . ’ sulphur trioxide, only a limited quantity of water would form in the converter. - „ I have found that none of these proposals for handling relinery sludge is adaptable‘to alkyl ation sludge because of the differences `which exist between this sludge andthe usual refinery sludges dealt with by Hechenbleikner, Clarke and others. ~ ‘ To state my empirical ñndings shortly and con A typical alkylation sludge contains a relatively cisely, it is necessary to vaporize or atomize the high percentage of sulphuric acid, usually be 10 alkylation sludge and, while it is >in this con tween 83% and 90%. The total carbon content dition, `subject it to such a high temperature of the sludge is between 5% and 8% With about that any water ‘present is evaporated and _all 1% of free oil and 4% to 8% unsaturated hydro ' hydrocarbonaceous material present is burned to carbons. `This `sludge is quite different from the carbon dioxide and water. To accomplish this, usual sludge recovered from reñning of petroleum 15 it is necessary to burn additional fuel with the wherein the relative amounts~ of sulphuric acid alkylation sludge and this underV conditions that bodies and carbon bodies are quite different, there ` being usually ’considerably more carbon present so that the sludge can be readily worked up at insure complete lburning of the alkylation sludge. ' I have successfully operated by introducing air into the unit employed for heating and burning comparatively `low temperatures to give _a coke 20 the alkylation sludge in an amount sufficient to> ` residue, free of acid and having a. comparatively insure the presence in the gas remaining after high content of volatile hydrocarbons. A typical process for recovery of the acid and fuel Valdes from a petroleum reiinery' sludge is described in the Hechenbleikner Patents 1,953,225 and 1,953, 226. In the former patent, for-example, the acid sludge isv heated in a rotary kiln by direct con- „ tact with hot combustion gases. In elîect, the sulphur dioxide present is distilled out of the combustion of oxygen in excess of ‘that quan tity of oxygen required to convert the SO2 to S01. One of the principal objects of the present in~ vention, therefore, is to provide Va process for the recovery of the sulphur values in alkylation sludge as sulphur‘dioxide. Y Another object of the invention, and _no less material at a low temperature to le'ave a dry 30 important,` is to provide a process enabling re ' coke containing so high a content of volatile covery of the sulphur values in alkylation sludge _ hydrocarbons that the coke is useful -as 'a fuel. to be achieved as sulphuric acid. Because the gases issuing from the Hechen The invention includes other objects and fea- _ bleikner rotary kiln contain water and various tures _of advantage, some of which, together with condensable hydrocarbons in addition to sulphur 35 the foregoing will appear hereinafter. The single dioxide, it has been proposed to pass this ma figure in the drawing accompanying and forming terial `through a secondary hydrocarbon com a ypart of the following description is a combi bustion furnaceas ay means of removing the hy nation'diagram of the combustion chamber and drocarbons present so that they would be re ‘ a flow sheet of the process employed for recovery moved instead of burning subsequently in the 40 of the sulphur dioxide values as sulphuric acid. converters employed to -catalyze the reaction of sulphur dioxide and oxygen to form sulphur tri oxide. Thus, Clarke states in Patent 2,019,893 _ ' Referring tovv the drawing, the» numeral l0 designates a burner comprising a sh'éll ll con structed of suitable refractory material, such as flrebrick, and defining a combustion chamber l2 drocarbons be removed by refrigeration, unless. 45 of preferably cylindrical cross section. Surround this was practiced with extraordinary care and ing shell Il is a steel casing I3 acting as 4a pro With elaborate equipment, complete removal tective reinforcement. The outside of the steel could not be secured. As a consequence,A water shell Ais preferably covered with suitable heat in would form in the converters and would 'make sulating material Il. ' diiiicult the subsequent condensation of the sul 5.0 At one end of the reaction chamber .l2 and phur trioxide. Clarke proposed limited burning preferably centrally'thereof is provided an alkyl of the hydrocarbons in the gases -removed from ation sludge atomizing and injecting device l5 the` rotary kilns so that, upon the subsequent for discharging a mixture of atomized sludge addition of the necessary quantity of air re and air -into the reaction chamber I2.- Placed quired for conversion of the sulphur dioxide to about the alkylation sludge atomizing device I5 ‘ that’ while Hechenbleikner suggested these hy 2,466,890 . *it are a plurality of fuel burning devices I6. These are placed as a ring about the alkylation sludge atomizing device I5 so that the flame path from each burner I6 is directed into the stream is suing from the alkylation sludge atomizing device. ` 4 is removed. The gases then pass on through pipe 24 to a ñlter 25 wherein mechanically entrained solid material and suspended droplets of sul phurìc acid are removed. The filtered gas is then passed through pipe 21 into a drying tower 28 where the gases are brought into contact with high strength sulphuric acid to reduce the water At the `other end of the combination cham contentto that quantity essentlaldîor good oper ber I2 several ïtiers of checkerwork, ‘usually made ation of the sulphur dioxide conversion unit. of refractory brick, are provided. These `serve several'purposes. First, they act as a means for 10 The gases are Withdrawn through pipe 29 by blower 3l -and are forced on' through a pipe 32 radiating heat back into the combustion chamber into a ñrst heat exchanger 33. From this-they to insure that the temperature therein is main pass through pipe 34 into a second heat ex . tained suii‘iciently high so that the atomized changer 36. In each heat exchanger, as will be sludge is subject to an adequately high temper presently explained, the gases are heated by heat ature and is quickly brought up to' that point exchange with the gases issuing from the con Whereat hydrocarbonaceous materials present are verters employed. The hot dry gases then pass transformed to carbon dioxide and water. Sec through pipe 31 through the first converter 38 ond, the checkerwork brick lserve as a support wherein at least a portion of the SO2 present for suitable catalytic material for furthering the combustion of carbon and hydrogen in the fuel 20 is caused, because of the presence of the catalyst in the converter, to react with the oxygen pres and in the sludge before the gases pass out through outlet I8. _ ~ ent and form sulphur trioxide. From the con verter the gases pass through pipe 39 through the heat exchanger 36 to heat gases passing erably made cylindrical in shape and compara tively of large capacity so that gases have ade 25 therethrough, then on through pipe 4| to the second converter 42. From this gas`es now free quate residence time in the combustion chamber. of SO2 and containing sulphur only in the form In one successful plant Iemployed a combustion of sulphur trioxide, pass through pipe 43 into the chamber 12 feet in diameter and 25 feet in overallA heat exchanger 33, from which they pass through length. This handled 8,000 pounds of alkylation sludge per hour. The furnace volume should be 30 pipe 44 to the absorbing tower 46 wherein the sulphur trioxide is taken up by water to form comparatively large for the weight of the sludge sulphuric acid. handled to insure ample residence time. In the As a speciiic operation illustrative of the prac specific> example the furnace volume is 35 cubic tice of this invention the following is set forth. feet per hundred' pounds of sludge per hour. This can be lowered to 15 cubic feet or increased, al 35 An alkylation sludge was employed containing 87% H2504, 6.5% carbon, 1% hydrogen, 3% wa though,if this is done the chamber size becomes ter, and about half of 1% free oil and a consid uneconomical, and 50 cubic feet is usually a max erable quantity of dissolved sulphur dioxide. I imum. injected 8.000 pounds of the sludge per hour to The fuel and alkylation sludge supplied are _ mixed with sufiicient air to insure that all car 40 gether with 6,700 cubic feet of refinery waste gases. Burning of the waste gases resulted in bon, hydrogen and sulphur in the gases issuing the sludge being consumed in the combustion through the exit I8 are respectively converted chamber I0 vat a temperature maintained be to 4carbon dioxide, water and sulphur dioxide. To tween 1500° and 1800" F., suñìc’ient air being sup secure this, the necessary quantities of excess air are added, taking into account the composition 46 plied to insure the carbon present was converted to carbon dioxide, the sulphur present was all in of the fuel burned and the alkylation sludge. the form of sulphur dioxide while all hydrogen Usually the quantity of air introduced is such In practice, the combustion chamber I2 is pref that oxygen need not be supplied upon the con version of the sulphur dioxide to'sulphur trioxide. present was oxidized to form Water., The com bustion gases formed Were passed through the As a suitable fuel I have successfully employed 50 apparatus previously described, being reduced in temperature to '15 degrees F. as they issued from refinery waste gases although one can use oil, natural gas, sulphur or hydrogen sulphide. Usu the filter 26 and having a water content of only ally, however, sulphur will not have sufficiently 8 milligrams of water per cubic foot as gases high heat imparting capacity to suñice alone and. passed from the drying tower 28 through pipe while it can be used as supplementary fuel and 55 29 into the conversion unit. to provide a gas rich in sulphur dioxide, usually Since the present invention is not concerned some quantity o_f oil or other fuel will have to be with the details of mechanical construction, the burned. Hydrogen sulphide alone will supply drawing is really more in the nature of a ñow suiiicient heat, usually one part by weight of hy sheet. It should be understood, of course, that drogen sulphide to two parts of alkylation sludge. 60 various modifications in equipment and arrange Before the gases are passed to the sulphuric ment` may be necessary to meet the particular acid plant, I remove substantially all water. This conditions in different plants and these are in is accomplished by passing the gases, preferably cluded in the invention. For example, instart through a waste heat boiler, pipe I9 leading from exit I8 passing to waste heat boiler 2 I. Here the 65 ing up such plants auxiliary heat must be pro vided, because the temperature is insufficient to gases are cooled down to a considerable extent, permit the catalytic oxidation of sulphur diox depending upon ,the heat economy desired. The ide to commence unless the bodies of catalytic partiallyA cooled gases then pass through pipe materials in the converter are brought up to tem 22 to a cooling tower 23 where the gases are fur ther lowered in temperature, preferably by bring 70 perature. A suitable starting furnace will enable this to be achieved. It is, therefore, essential but, ing them into direct contact with a cold water . since it forms no part of the present invention, spray. If one cooling tower does not sufñce, an neither it nor the various valves nor the other other or additional cooling means may be pro control mechanisms, pumps. etc., are shown, vided. In any case, the gases are lowered to a temperature whereat most of the water present 75 these being readily provided by those skilled in 2,406,890 6 5 the art in view' of the foregoing adequate dis closure.- " lytic material _promoting combustion of carbon and hydrogen with oxygen, said process compris In connection with the catalytic material car ing burning a fuel withexcess airV in said com ried by the checkerwork l1, I preferably employ materials which will promote the combustion of carbon and hydrogen to carbon dioxide and wa ter although the extended surface of the check erwork acts in part in this way. Such catalysts bustion> chamber to heat said extensive surface and said brick checkerwork and to supply radiant heat to said chamber at a temperature of above 1500° F., spraying the sludge into said combus tion chamber to evaporate water therefrom and are, for example, metal salts such as a 0011961’ burn with said excess air substantially all carbon, . gen, said process comprising burning a fuel with excess air in said combustion chamber to heat said extensive surface and said brick checken.V work and to supply radiant heat to said chamber at a temperature of above 1500*’ F., spraying the 25 must pass, said process comprising burning a fuel with excess air in said combustion chamber to heat said extensive surface and said brick check hydrogen and sulphur compounds respectively salt and other metals. .These _catalysts are well to carbon dioxide, water, and sulphur dioxide and known as is the impregnation of the brick. _ ' passing the resulting gases through said checker I claim: ` Work to ensure completion of the carbon and hy 1. A process for ‘converting an alkylatibn sludge containing sulphuric acid and sulphur compounds drogen oxidation. ` 4. A process for converting sludge containing to sulphur dioxide in a combustion chamber hav 15 hydrocarbonaceous material, sulphuric acid and ing an extensive internal surface and brick check sulphur compounds to sulphur dioxide in acom erwork at one end thereof through which gases bustion chamber having an extensive internal issuing from the chamber must pass, said check surface and brick checkerwork at one end thereof erwork bricii- carrying catalytic material promot through which gases issuing from the chamber ing combustion of carbon and hydrogen with oxy sludge into said combustion chamber to evaporate erwork and to supply radiant heat to said cham- ' - ber at a temperature of above 1500° F., spraying l the sludge into said combustion chamber to evap Water thereform and burn with said excess air orate water therefrom and burn with said excess air substantially all carbon, hydrogen and sulphur substantially all carbon, hydrogen and sulphur compounds respectively to carbon dioxide, water, and sulphur dioxide, passing the resulting gases through said checkerwork to ensure completion of the carbon and _hydrogen oxidation, cooling the compounds respectively to carbon dioxide, water, and sulphur-dioxide, passing the resulting gases through said checkerwork to ensure completion of the carbon and hydrogen oxidation, cooling gases issuing from -said furnace after passage through said checkerwork to condense the major the gases issuing from said furnaceafter `passage through said checkerwork to condense the major ‘ portion of water in said gases, separating said 35 Portion of water in said gases, separating said condensed water and drying the remaining gases with concentrated sulphuric acid to remove sub stantially all the water therefrom. 2. A process for converting sludge containing condensed water and drying the remaining gases with concentrated sulphuric acid to remove sub stantialiy all the water therefrom. 5. A process forconverting sludge containing hydrocarbonaceous material, sulphuric acid and 40 hydrocarbonaceous material, sulphuric acid and sulphur compounds to sulphur dioxide in a com- \ sulphur compounds to sulphur dioxide `in a com bustion chamber having an extensive internal sur bustion chamber having an extensive internal face and _brick checkerwork at one end thereof surface and brick checkerwork at one end thereof through which gases issuing from the chamber through which gases issuing from the chamber must pass, said checkerwork brick carrying cata must pass, said process comprising burning a fuel lytic material promoting combustion of carbon 45 with excess air in said combustion chamber to andhydrogen with oxygen, said‘process compris `heat said “extensive surface and said brick check ing burning a fuel with excess air in said com erwork and to supply radiant heat to said cham bustion chamber to heat saidI extensive surface ber at a temperature of above 1500“ F., spraying and said brick checkerwork and to supply radiant the sludge into said combustion chamber to evap heat to said chamber at a temperature of above 50 orate water therefrom and burn with said excess 1500° F., spraying the sludge into said combustion chamber to evaporate water therefrom and burn with said excess air substantially all carbon, hy air substantially all carbon, hydrogen and sul- ' phur compounds respectively to carbon dioxide, water, and sulphur dioxide and passing the re sulting gases through said checkerwork to ensure drogen and sulphur compounds respectively to _ carbon dioxide-water, and sulphur dioxide, pass 55 completion 'of the carbon and hydrogen oxidation. ing the resulting gases through said checkerwork 6. A process for converting an alkylation sludge to ensure completion ofthe carbon and hydrogen containing sulphuric acid into gases'containing sulphur dioxide which comprises burning'gaseous oxidation., cooling> the gases issuing from- said furnace after passage through said checkerwork fuel inthe presence of excess air lin a combustion to~condense the major portion of water in said 60 chamber. preceding and heating an extensive gases, separating said condensed water and dry course of checkerwork in the furnace so as to ing the remaining gases with concentrated sul maintain a temperature above 1500“ F.. in saidv phuric acid to remove substantially all the water ~ chamber spraying the strong alkylation acid - sludge into `the name of combustion, and then 3. A process for converting sludge containing 65 passing the resulting >gases through said checker therefrom. _ - ` hydrocarbonaceous material, sulphuric acid and sulphur-compounds to sulphur dioxide ina com bustion chamber having an extensive internal _ work, the excess of air beingsuflicient to burn _ the carbonaceous matter in said sludge but insuf iicient to dilute the S0: content of the gaseous surface and brick checkerwork at one endl thereof. „ >_products below the content suitable for use in the through which gases issuing from the _chamber 70 sulphuric acid contact process. . must pass, said checkerwork brick carrying cata _ ‘ _ t 4, , ALBERT C. MOHR.