CONTINUOUS-LINE OPERATIONS FOR DESULFURIZING COAL

Abstract: Continuous-line operations for desulfurizing coal utilizing fluid treatments including gaseous reactant treatment of raw coal. Raw coal is pulverized at (20) to a selected particle size classification. Moisture level is controlled to provide desired work product characteristics enabling impingement with a reactant gas while avoiding dispersion of the work product and maintaining desired properties for mechanical control of movement through reaction zones. Reactant contact control includes control of rate of movement of the work product, control of reactant injection, and control of reaction time while maintaining continuous-line movement of the work product. Provision is made for ease of separation of extracted sulfur as useful by-product and passivation treatment is applied to the desulfurized coal.

Description: CONTINUOUS-LINE OPERATIONS FOR DESULFURIZING COAL / This invention relates to desulfurization of coal; more specifically, the invention is concerned with continu¬ ous-line operations enabling multiple fluid treatments of coal to extract sulfur and recover useful by-product containing such extracted sulfur. Coal from many regions cannot meet requirements for use as a fuel by industries, such as public utilities, because of sulfur contents above .1.1% by weight. Burning of such coals produces levels of sulfur dioxide in the atmos- phere which have been asserted to be a major contributor to acid rain. Research efforts to extract sulfur from coal be¬ fore burning have been continuing for many years. Chemical treatments of many types have been advanced for batch processing of solid carbonaceous fuels. And, use of solvents, such as liquid hydrocarbons for continuous processing has been disclosed. But, prior to the present invention, commercially acceptable production of "compliance" coal has remained an objective. The present invention enables continuous-line operations in which multiple treatments, utilizing gaseous and liquid reactants, can be carried out while the coal is continuously moving at commercially economic rates; such continuous-line processing being carried out without hazard to the environment or personnel, and without use of combustible solvents such as liquid hydrocarbons. Teachings of the present invention enable continuous-line desulfurization of coal as found in its differing geological phases notwithstanding variations in characteristics encountered, such as levels of sulfur and moisture, or differences in physical properties such as hardness, to produce "compliance" coal; i.e. a coal with less than 1.1% sulfur by weight. In addition, such continuous-line desulfurization is carried out without requiring application of external heat or pressure, without generation of hydrogen sulfide nor significant concentrations of sulfuric acid, and while con¬ verting extracted sulfur into useful by-product, readily removable from the coal, and delivering coal of less than !_.!% sulfur content which is conditioned to inhibit reabsor tion of sulfur before its usage as a solid carbonaceous fue Other advantages and contributions of the inven¬ tion are considered in description associated with the accompanying drawings, in which: FIG. 1 is a schematic general arrangement view of continuous-line apparatus for carrying out the invention; FIG. 2 is an enlarged elevational view, with por¬ tions cut away, of the feed additive portion of FIG. 1; FIG. 3 is a top plan view of the apparatus of FIG. 2 with portions cut away; FIG. 4 is a side view of the apparatus of FIG. 2 with portions cut away; • * FIG. 5 is an elevational view, with portions cut away, of apparatus for providing a zone for continuous movement of work product during reactant treatment; FIG. 6 is a top plan view of the apparatus of FIG. 4 with portions -cut away; FIG. 7 is a cross-sectional view of the apparatus of FIG. 5; FIG. 8 is a schematic illustration of stacked reaction chambers of the type shown in FIGS. 5-7; FIG. 9 is an elevational view of passivation structure for carrying out the invention; and FIG. 10 is a flow chart for describing control functions carried out in the continuous-line operations of the present invention. Batch processes have been proposed for chemically desulfurizing coal in which treatment of a particular batch can be readily tailored to the variable ' s encountered in handling coal from differing geographical regions and in its differing geological phases. Such variables have fore¬ stalled development of continuous-line operations; although use of hydrocarbon solvent liquor has been proposed, no commercially practical continuous-line operation for chemic- ally extracting sulfur by gaseous reaction has been advanced Significant and important contributions of the invention comprise: establishing the control adjustability required by the variables of raw coal in continuous-line operations, providing improved uniformity of treatment and results without requiring the coal-to be in a slurry or liquid state for desulfurizing reactions, and, enabling economic handling of large quantities of coal at production rates -capable of meeting demands made, e.g. by modern electrical generating plants. The basic chemical reactions for desulfurizing coal in other than a slurry or liquid state, while not pre¬ viously made practicable in continuous-line operations, have been known. E.g., use of nascent oxygen for chemically extracting sulfur from the coal is disclosed in copending U.S. application Serial No. 223,274, entitled "REMOVING SULFUR AND BENEFICIATING COAL", filed January 8, 1981; such disclosure is incorporated herein by reference. In carrying out the invention, raw coal is analy¬ zed for such characteristics as sulfur and moisture contents The raw coal is fed at a controlled predetermined rate into sizing apparatus which is selected based on the hardness characteristics of the coal. Hard coals require a crusher while a.rotary breaker can be used on softer coals to obtai desired sizing results. Nominal 3/8" by 0" is a preferred sizing classification; the particle sizes and distribution in this classification are well known and would include particles in the 30-60 mesh size and so-called _. _ OMPI "superfines" of about 200 mesh size. Referring to FIG. 1, . aw coal is accumulated in bin 10 and directed with its rate of delivery in tons per hour controlled by variable rate feeder 11. Slate and other refuse is separated on picking table 12 leading to feed conveyor 14; and magnetic particles can be separated b magnet 15. Grab sampler 16 takes samples of the raw coal for verification analysis of moisture and sulfur contents provided earlier with bulk deliveries of raw coal. In the embodiment shown, coal is fed into a pulve izing means in the form of crusher 20 and ground to a sel¬ ected particle size classification which will make sulfur sites accessible to nascent oxygen with control of reaction percentage available notwithstanding continuous movement. Crushers are used for coal hardness classifica¬ tions above fifty-five on the Hardgrove Grind scale; and rotary breakers are used for softer coals. Rotary breakers separate rock and similar refuse longitudinally of a rotat¬ ing drum so that a picking table would not * be required for separating refuse. Operation of various types of coal pul¬ verizing means usable in the invention is well known. About 1% by weight of the calcium stoichiometric- ally required is supplied as lime from bin 24 and delivered as shown into the pulverizing means 20 for grinding with th raw coal. This calcium reacts with surface sulfur exposed OMFI during pulverizing. The coal in solid pulverant form is transported by conveyor 26 which includes scale 28 for quantitatively determining the feed rate. Preparing such pulverant-raw coal for continuous- line treatment operations is an important aspect of the invention. Additives to the coal to form the desired work product are made in feed- additive chamber 30. The pulverant coal and lime should have sufficient moisture so that it will agglomerate,- i.e. hold together so that it will not be blown away by gaseous treatment yet remain friable for desired movement and exposure. Moisture level is controlled to enable formation of sulfate ions and avoid generation of hydrogen sulfide. The calcium, generally added as agricul¬ tural lime, forms calcium hydroxide which reacts with the intermediate sulfuric acid ions to form calcium sulfate. In this form, the extracted sulfur can be readily processed in continuous-line operations. Water as required and calcium are controllably added in the feed additive chamber 30. The amount of water added is related to the moisture content of the coal. The water helps drive the desired reaction and is controlled to provide a work product which is moisture agglomerated to facilitate gaseous treatment while avoiding a slurry or liquid-like stage. In general, the moisture content of run-of-the- mine coal will be about 6% to 8% by weight. Moisture is V raised in the feed additive chamber 30 to about 10% to 12.5% to produce the desired work product. calcium addi¬ tions are stoichiometrically controlled to avoid acidic conditions. Calcium is generally added as lime (CaO) but is adaptable to addition as calcium hydroxide while pro¬ viding for staying within desired moisture level ranges. The ratio of lime to coal by weight is determined by the sulfur content of the raw coal. A commercially available wetting agent, such a Tergetol, or a glycol, or mixtures of these, from source 32 is added at about .001% by weight per ton of coal to help minimize the amount of water required to. produce the desired agglomerating properties in the work product which facili¬ tate reaction rather than dispersion by gaseous treatment. Water is added, as required, to provide sufficient moisture for sulfate ions to enter solution while avoiding a liquid¬ like state which could decrease reaction efficiency. In addition to the moisture content of the raw coal as provided, sources of water include available water should calcium be added as calcium hydroxide, water available when hydrogen peroxide solution from source 34 is used (dependent on sulfur content of the coal), and water from source 35. When sulfur content of the raw coal is about 4% by weight, or higher, a solution of 3% to 30% hydrogen peroxide is added in the feed additive chamber 30 to help activate the work product for gaseous treatment. Total moisture limited to that which produces the desired work product for gaseous treatment, generally about 10% to 12.5% by weight. A reaction zone is provided for such work product wherein sulfur reaction percentage can be controlled mechan- ically through control of such factors as work product move- ment rate, reaction gas feed rate, and expansion of the space -occupied by the moisture agglomerated work product to permit repeated all-surface contact of the particles. The work product is fed, as indicated, into longitudinally-extended reaction zone 36 defining an elongated travel path for gaseous treatment between inlet opening 38 and outlet opening 40 where rate of movement can be controlled and the space occupied by the work product can be expanded to obtain the desired contact for reaction. Oxygen from source 42 and air from compressed air tank 43 are made available. Preferably pure oxygen is used in ozone ' generator 44. The reaction gas is controllably injected into sulfur-extraction zone 36 so as to control reactive contact and.time of contact with the work product during its controlled movement. Ozone level is predetermined at a percentage by volume of a gas mixture in which the balance is preferably air; while volumetric percentage of 3% ozone is generally preselected, higher percentages of ozone can be used with sulfur contents such as 5% or higher. In the sulfur- extraction reaction zone 36, the chemically active nascent oxygen seeks out sulfur sites for oxidation. In the pre¬ sence of moisture, extracted sulfur forms sulfate ions and in the presence of calcium forms calcium sulfate. To control exothermic reactions in zone 36, temperature sensors measure the temperature in the gas reac¬ tion zone 36 and, quench cooling fluid is provided respon¬ sive to the temperature level so that work product does not exceed 100°C. ; the preferred reaction zone temperature is about 50°C. Quench cooling water is available from source 35. Water cooling is preferably carried out contiguous to discharge opening 40 in order to minimize the amount of water present during gas reaction so that the work product does not take on liquid-like properties which would inhibit desired gas reaction. Quench cooling can be implemented with air from source 43 to reduce cooling water requirements or implement water pressure. Quench cooling injectors extend over a major portion of the length of the reaction zone 36 and locations for quench cooling injection can be selected for water and/or air injection. Quench cooling helps control the temperature of the reaction and/or the product and avoids potential steaming which would be detri¬ mental to reaction and interfere with desired flow through interconnected structures. The work product is delivered through enclosed discharge means 40 into a longitudinally-extended conversion zone 50 defining an elongated travel path in which the calcium sulfate is converted into an ammonium sulfate. Higher moisture content occurs in conversion zone 50 due to either quench water addition shortly prior to entry into conversion zone 50 or to the addition of ammonia as ammonium hydroxide. Moisture content of about 15% is provided in carrying out the following reaction in the conversion zone 50: 2CaS0 4 + 4 NH 4 0H 2(NH4) 2 S0 4 +2Ca(OH) 2 At discharge end 54 of conversion zone 50, the work product contains pulverant coal, diammonium sulfate on the surface of the coal, and* calcium hydroxide. This work product is delivered through chute 56 below spray washer 60 along screening path 61. Water and air at elevated pressure from a plurality of nozzles extending along the travel path impinge on the work product in spray washer 60 to dislodge the diammonium sulfate; sump 62 accumulates water, diammonium sulfate, calcium hydroxide, and a small percentage of coal superfines (around 200 mesh and smaller particle sizes) which may pass through the wash screen of path 61; such coal superfines which, dependent on the type of coal and pulverizer can exceed 20%, are recovered. The bulk of the coal continues along travel path 61 through dewatering screen means 68 and is discharged into cyclone dryer 70. The materials in sump 62, including water, di¬ ammonium sulfate, calcium hydroxide, and the coal superfines and any remaining calcium sulfate, are discharged into a cyclone separator 74. The coal fines are separated for travel along conveyor 76. The remaining solution is dis¬ charged into cyclone separator system 78 for recovery of water, which is returned to water tank 35 for recycling, and selective separation of remaining by-product which can include precipitation separation of the diammonium sulfate for separate accumulation or combined accumulation of the ammonium sulfate and calcium hydroxide. The pulverant coal of decreased sulfur value is weighed at scale 90 while traveling along conveyor 76 to a longitudinally-extended passivation zone 92 defined by wall structures in which the sites, from which sulfur has been removed are deactivated. Passivation agent from source 93 is injected along the elongated passivation travel path of the coal for repeated contact with all surfaces of such coal to passiyate such sites with carbon dioxide supplied, e.g. by carbonic acid. From passivation zone 92, the coal travels along- conveyor path 94 to stockpile 95. FIGS. 2, 3, and 4 illustrate in more detail the feed additive means for establishing the desired moisture agglomerated work product and stoichiometric balance for the calcium. Lime from source 24 is distributed over the fu - URE OMPI width of conveyor belt 102 by lime distributor screw 104 within distributor housing 106. / Feed rate of lime is con¬ trolled by variable speed drive 108 responsive to stoichio¬ metric requirements based on raw coal, analysis. A lime chute 110 extends to the proximity of raw coal conveyor belt 102. Wetting agent, at a fixed rate per ton of coal, is added through the bank of sprayers 120 under control of valve 122 responsive to the tons per hour feed rate of the coal. Water is added through the bank of sprayers 130 under control of valve 132 responsive to the moisture content of the coal and the tons per hour feed rate. With this arrangement, uniform distribution of additives and contact with the raw coal across the full width of the conveyor belt for thorough mixing and the desired moisture agglomerated work product are established contiguous to the entrance portion of gas reactor 36. An important contribution of the invention is pro¬ vision for control of the gaseous treatment while maintain- ing movement of the work product at commercially acceptable rates. Both ozone content and rate of injection of reaction gas can be. controlled, e.g. in sulfur extraction zone 36. Desired reaction time is achieved by controlling rate of movement of work product along ah elongated travel path and/or by extending the length of such travel path for reac¬ tion. Access to the work product for reaction is brought about by expanding the space occupied by the pulverant work product during its longitudinal/movement and by selected distribution of injection of reactants along the treatment path. Specific structure for achieving desired control of rate of movement and treatment contact is shown in FIGS. 5-, 6, and 7. Within enclosure wall 140, a ribbon-band auger 142 is rotated about longitudinal axis 144 with the revolu¬ tions per minute being controllable by variable speed motor drive 146 to control longitudinal rate of movement of the work product. Paddles, such as 148 distributed along and integral with ribbon band auger 142, provide a tumbling and cascading action for access of reaction gas. Such paddles provide a mixing action at the entry portion of the reaction zone. Manifold connectors 150, 152, and 154 provide for separate' injection of water, air and reactant gas. As seen in FIG. 6', each communicates with a manifold such as 155, 156, 157 extending along the travel path of work product with nozzles such as 158 (FIGS. 5 and 6) distributed longi¬ tudinally. Fluids can be injected in a direction transverse to the direction of movement of the work product to impinge directly on the work product during its movement along the travel path. The length of the travel path for direct reac- tion with injected gas can be selected within the ribbon- screw conveyor by selective activation of injectors along the length of the manifold, and reactors can also be stacked in series to add to reaction travel path length. •A work product inlet 160 is defined by framing structure 161 which connects to feed additive chamber 30. Work product is discharged through discharge opening 162 defined by chute framing structure 163. Substantially identical structures can be used in series to provide for continuous movement of work product in sulfur-extraction zone 36 and in sulfate conversion zone 50 (FIG. 1) . Each is operable with an opposite direction of travel as stacked in series with the gas reaction zone being located above the conversion zone for sequential feed, by gravity, from one zone to another. A ribbon-band auger for the conversion zone can be driven from the same variable speed drive means used for the gas reaction zone auger but with the conversion zone auger geared for a higher rate of movement. Or, preferably, separate drives are used for each auger but with coordinated rates of movement to move work product through the conversio zone so as to avoid back-up into the gas reaction zone. In the embodiment of FIG. 8, parallel-path gas reaction chamber structures are stacked so as to increase the gas reaction travel path length without diminishing the desired rate of movement for work product along the continuous line. Work product from feed additive chamber 30 is divided in a division chute which includes a flop gate 165. Gas reaction structures, of the type shown in FIGS. 5, 6, and 7, are stacked i'n path 166 and path 167; feed through connector chute 168 leads into conversion chamber 50 for further processing as .described in relation 5 to FIG. 1. Flop gate 165 can also be positioned to provide a single gas reaction path. When the structure of FIGS. 5-7 is used as a gas reaction zone, provision is made for sensing the temperature along the longitudinal length of the reaction zone by sensor 10 such as 170 (FIG. 7) distributed along its length; and by temperature sensor 172 contiguous to its discharge end (FIG. 5) to continuously monitor the temperature of treated work product. Other conditions, such as a change in chamber pressure caused by an obstruction, can be determined by 15 sensing means such as 173 (FIG. 7) distributed longitudinall The invention provides an elongated travel path for passivating sites from which sulfur has been removed; specific structure for passivating coal of decreased sulfur value is shown in FIG. 9. Conveyor 180 dumps the pulverant 20 coal into passivation chamber 182 defined by top wall 185 and sidewalls such as 186 and 187 which form a confined path; the passivation chamber empties onto conveyor 188. Within passivation chamber 182, baffles 190, 191, 192, and '•* . 193 are distributed along the elongated passivation travel 25 path such that coal delivered by conveyor 180 drops, as shown, into contact with baffle 190 on which it rolls and tumbles toward baffle 191. Passivating agent injection nozzles 194, 195, 196, and 197 are strategically placed at the distal end of each baffle such that pulverant coal rolling from baffle 190, for example, is impinged by passi- vating agent injected through nozzle 194 into the passiva¬ tion chamber in a direction transverse to the direction of travel of the pulverant coal through the passivation chamber. The rolling action and change of direction at each baffle assures that all surfaces of the coal will be con- tacted for passivation treatment. For operator control purposes, sulfur content (in % by weight) and moisture content (in % by weight) are pre¬ determined as bulk loads of raw coal are received; samples of raw coal selected at regular intervals by grab sampler 16 are used to verify or correct the analysis. A moisture probe near the outlet of hopper 10 (FIG. 1) can be relied on for changing conditions due to exposure of stockpiled raw coal to weather. Such values are fed to an operator control panel. The feed rate (tons per hour) of the raw coal is determined at scale 28 and similarly indicated. The sulfur content and raw coal feed rate determine the amount of cal¬ cium added as lime (CaO) in lbs/ton of coal. The' ozone fee rate in lbs/ton of coal based on sulfur content is predeter¬ mined. The rate of movement of work product (in tons per hour units) through the reaction zone 36 can be related to sulfur content. PI A control flow chart fσr describing the basic con¬ trol functions for carrying out''the present invention by an operator is shown in FIG. 10. Raw coal analysis indicated at 200 provides moisture and sulfur content which determina- tions are used as indicated by 201, 202. The water addition control, indicated at 203, includes control of the moisture level selected to achieve the desired moisture agglomerated work product. The sulfur content 202 is used for reaction zone control, indicated at 204, along with the determination of raw coal feed rate indicated by 205, to control lime addi tions carried out by lime additive drive means 108. Sulfur content and feed rate of raw coal are used to control intro¬ duction of reactant gas as indicated at 207 and, in turn, introduction of conversion reactant indicated at 208. Treatment zone control 204 also includes control of the rate of movement of work product through the gas reaction zone indicated at 210 which in turn controls the rate of movement indicated at 212 for work product through the conversion zone through control of the ' variable drive means for their respective augers. Reaction zone temperatures indicated at 214 are used to contr l quench water, and/or air, indicated at 216; temperature determinations can be directed to reaction gas input control 207 to diminish reactant input when maximum desired temperature levels are reached. Gas reaction pH, in¬ dicated at 217, can also be used to control lime feed r. £U £A OMPI ' .Control station input data includes sulfur and moisture content in percent by "weight and feed rate of coal in tons per hour. The sulfur content determines the amount of lime to be added which should be at least that stoichio- metrically required to achieve compliance levels of sulfur but can be that stoichiometrically required, dependent on desired percentage reaction, to remove all sulfur. The conversion reaction is directly related, and is at least that required to produce compliance coal but can be con- trolled by the operator to be at or near full removal of sulfur. The moisture content determines water additions from various sources as previously described to establish desired work product characteristics. The sulfur content and physical properties of the raw coal also effects reaction exposure as does the desired reaction percentage. Coal feed rate is preferably kept at full capacity, such as 250 tons per hour, and the reactions are controlled relying on pulverizing coal to desired par¬ ticle size range, feed rate of reactants, and through special measures as may be required for higher sulfur con¬ tents and harder coals including extended reaction times while maintaining production rate. Higher sulfur contents require higher percentage reaction. In the following examples, raw coal is fed at a rate of 250 tons per hour; unless otherwise indicated, addi¬ tive feed values are in pounds per ton of coal: Example 1 Example 2 Example 3 Sulfur Percentage 2-1/2% to 1% 4% to 1% 6% to 1% Reduction Water Addition for 6% Moisture Coal not to Exceed: 180# 180# 180# Sulfur Weight to be Removed 30# 60# 100# % Reaction • 60% 75% 83% Sulfur Expressed as FeS 2 byWeight 56# 112# 187# Ozone Required 56# 112# 187# Oxygen* to Ozone Generator per Hour 1870 ft 3750 ft 3 6240 ft 3 100% Ca0 2 Lime . 18# 35# 58# NH 3 32# 64# 106# (NH 4 ) 2 S0 4 124# 247# 412# Prnrlnnβi. * In cubic feet measurements as supplied commercially. The sulfur-extraction zone auger would be rotated at thirty four (34) RPM and the conversion zone auger would be rotated at about thirty five (35) RPM with a ribbon band of four (4) feet outer diameter and thirty (30) inch inner diameter in zones of twenty foot length. Rate of movement of work product through conversion zone 50 should be 5% greater than the rate of movement through zone 36. Movement of the work product after exit from conversion zone 50 is esta¬ blished and maintained for handling all materials at full ■ CΓ EA C O PΪ capacity for the system, i.e. at a rate of movement for work product in excess of that /through the conversion zone in order to avoid back-up of work product and to accommod¬ ate the volume of spray wash added. Subsequent conveyors, passivation equipment, cyclone separators and dryers are maintained at corresponding full capacity rates during operations. Spray washing is carried out with water augmented with air at a pressure required to dislodge diammonium sulfate, generally about seventy five to one hundred psig. Conventional air compressing equipment of about one hundred twenty five horsepower rating can be used for a two hundred fifty tons per hour system. Inclined vibrating dewatering screens used after spray washing can be conven- tional equipment. Individual cyclone separators of conven¬ tional structure and operation can be used for functions of the present invention such as separating coal fines which pass through the washing and dewatering screens, separating water for recycling, and separating by-pro * duct; diammonium sulfate separated at 78 can be delivered for silo accumula¬ tion as shown; operation of such structures requires no further description for an understanding of the present invention. Conventional solenoid-operated valves are used fo flow rate control of fluids and conventional controls for variable speed electric motor drives are utilized. Coal sampling means and analysis methods, and condition sensors for temperature, pH, and pressure, as well as samplers for determining ozone level, are well known in the art so that further description of operation would not be required by one skilled in the art for an understanding of the inven-. tion. Representative equipment for an installation with a two hundred fifty tph capacity would include: Coal scales - Model 20-30 inch available from Ramsey Engineering Co., St. Paul, Minnesota Pulverizing means: Impact Crusher of the 3 roll, 2 stage type, 48" size available from McClanahan Corp . , Hollidaysberg, Pennsylvania, or Rotary Breaker - 12* diameter, 16" long, with 1/2" screen openings available from Mill Machine Works, Inc., Springs, Pennsylvania Conveyor equipment for : Raw coal - Model 250T-30-80 available from Miller Machine Works , Inc . , Springs , Pennsylvania Pulverized coal - Model 250T-30-160 available fro Miller Machine Works , Inc . , Springs , Pennsylvania . -£U REA OMPI Treated coal - Model R 250T-30-160 available from Miller Machipe Works, Inc., Springs, Pennsylvania Vibrating Dewatering Structure - Model LH2-8-16 avail- able from Allis Chalmers, Appleton, Wisconsin Cyclone separator 70 - Model VC-48 available from C&M Industries, Inc., St. Louis, Missouri Cyclone separator 74 - Model EB-36 available from C&M Industries, Inc., St. Louis, Missouri Pumps - VOC Chemline available from Ingersol Rand, Trenton, New Jersey, with selected gpm ratings dependent on location of use within the installation Ozone generators available from Welsbach Ozone Systems Corp., Philadelphia, Pennsylvania Sulfur-extraction and conversion zone structures for a specific embodiment are horitontally-oriented, pro- viding for controlled movement of work product mechanically rather than pneumatically; details of reaction zone struc¬ ture usable in the present invention are disclosed in co- pending application Serial No. PCT/ entitled "STRUCTURE FOR CONTINUOUS-LINE COAL DESULFURIZATION REACTION"; passivating zone structure is vertically-oriented for movement of work product free of pneumatic or mec O PI drive means; details of passivating zone structure usable in the present invention are disclosed in copending applica tion Serial No. PCT/ , entitled "CONTINUOUS-LINE PASSIVATION STRUCTURE FOR DESULFURIZED COAL"; both such applications, filed concurrently herewith, are incorporated herein by reference. While specific structures and specific sulfur con tent coals have been set forth and described for purposes o disclosing the invention, it is understood that, in the light of the above teachings, other structures could be substituted in the combination and other sulfur content coals could be processed in continuous-line operations; therefore, in determining the scope of the present invention, reference should be made to the appended claims.

Claims: CLAI S 1. Continuous-line operations for extracting sulfur from coal and for separating by-product containing the extracted sulfur from such coal, comprising the steps of supplying pulverant coal having a sulfur content in excess of 1.1% by weight for treatment, such pulverant coal being supplied at a predeter¬ mined rate, controllably adding calcium to such pulverant coal and controlling moisture content to provide a pulverant work product, which is agglomerated by moisture, such calcium being added from the group consisting of- lime and calcium hydroxide, providing a longitudinally-extended sulfur- extraction reaction zone defining an elongated travel path which is enclosed in extending between charge and discharge means for such work product, delivering the moisture agglomerated pulverant work product into such reaction zone, controlling rate of movement of such work product through such reaction zone, supplying sulfur-extraction reactant including nascent oxygen, injecting such reactant into contact with the work product during its movement along the elongated reaction zone travel path to extract sulfur, quantitatively controlling injection of such reactant to decrease sulfur content of such coal to less than 1.1% by weight, such calcium additions to the pulverant raw coal being stoichiometrically controlled to enable formation of calcium sulfate from sulfate ions formed from the sulfur - extracted from the pulverant raw coal and to inhibit an acid condition in the moisture agglomerated work product during passage through such sulfur-extraction zone, providing means for separating pulverant coal, conveying treated work product containing pulver¬ ant coal from which sulfur has been extracted into such coa separation means, separating pulverant coal from such work product by separating by-product containing sulfur extracted from such pulverant coal, and delivering pulverant coal of decreased sulfur value. 2. The invention of claim 1 including the steps of providing a longitudinally-extended passivation treatment zone which is enclosed in extending between charge and discharge openings, delivering such pulverant coal of decreased sulfur value for movement through suclv passivation treatment zone, injecting passivating agent so as to contact such separated pulverant coal of decreased sulfur during movement through such passivation treatment zone, and delivering such surface-passivated pulverant coal - of decreased sulfur value. 3. The invention of claim 1 in which calcium additions are controlled to be at least that stoichiometric- ally required to form calcium sulfate from sulfur to be extracted from the coal and in which the step of supplying pulverant coal for treatment includes pulverizing raw coal within a predetermined particle size range in the presence of lime, such lime- forming a portion of such subsequent stoichiometric con¬ trolled additions of calcium to the pulverant coal to form the moisture agglomerated work product, such lime being added for such pulverizing step comprising about 1% by weight of stoichiometric calcium requirements. 4. The invention of claim 1 in which such pulver- izing step produces predetermined sizing of the raw coal of nominal 3/8" by 0" particle sizes. 5. The invention of claim 1 in which injection of sulfur-extraction reactant comprises injecting reactant gas into the sulfur-extraction reaction zone at locations distributed along the elongated reaction zone travel path with the reactant gas being injected into the reaction zone to provide a direction of impingement of such reactant gas with work product which is transverse to the direction of movement of work product along such elongated reaction zone travel path. 6. The invention. of claim 5 further including the steps of sensing temperature level in such sulfur- extraction zone, and quench cooling such reaction zone responsive to such sensed temperature level to prevent significant steam formation from water associated with such work product. 7. The invention of claim 6 in which such quench cooling includes injecting water at a location contiguous t such discharge means for work product from such sulfur- extraction zone. 8. The invention of claims 6 and 7 in which such quench cooling includes injecting air. 9. The invention of claim 1 further including th steps of providing a longitudinally-extended conversion zone defining an elongated travel path which is enclosed in extending between charge and discharge means for work product, delivering work product from such sulfur- extraction reaction zone into such conversion zone, controlling rate of movement of such work product through such conversion zone, supplying a sulfate conversion reactant contain¬ ing ammonia, injecting such conversion reactant into such con¬ version zone to contact such work product during its move¬ ment along the elongated conversion zone travel path to convert calcium sulfate formed from extracted sulfur into an ammonium sulfate and form calcium hydroxide, then separating the pulverant coal by spray washing work product from the conversion zone, and delivering by-product containing water, such ammonium sulfate and calcium hydroxide. 10. The invention of claim 9 in which such conversion reactant is distributed longitudinally along the elongated conversion zone travel path for injection in a direction which is transverse to the direction of movement of work product along such elongated travel path, and such ammonium sulfate comprises diammonium sulfate. 11. The invention of claim 9 including the steps subsequent to such spray washing of work product of separating water from such spray washed work product, and recycling such separated water. - 12. The invention of claim 9 in which the ammonium sulfate formed comprises diammonium sulfate includ¬ ing the step subsequent to such spray washing of work product of separating the diammonium sulfate from the remainder of the by-product. 13. The invention of claim 2 in which such passivation treatment includes a passivating agent selected from the group consisting of gaseous carbon dioxide and carbonic acid with injection of such passivating agent being distributed along the elongated passivation travel path for repeated contact with such pulverant coal during passage of such coal, along such travel path. 14. The invention of claim 1 including the steps of analyzing the sulfur-contaminated coal for sulfur content, and measuring the quantitative feed rate of such sulfur-contaminated coal as delivered for treatment, and in which injection of sulfur-extraction reactant gas is controlled responsive to such sulfur content analysis of the raw coal in coordination with such feed rate of raw coal to provide at least stoichiometric requirements for reducing sulfur content of the raw coal to less than 1.1% by weight. 15. The invention of claim 14 in which ozone is injected with such sulfur-extraόtion reactant gas to prov¬ ide nascent oxygen, and in which the percentage of ozone in such reactant gas is controlled at a predetermined percentage by volume of such reactant gas. 16. The invention of claim 1 in which the raw pulverant coal has a moisture content level of less than 10% including the steps of analyzing the raw coal for moisture content percentage by weight, controllably adding wetting agent to such pulver¬ ant coal delivered for treatment, and in which such control of moisture content includes controllably adding water to the pulverant raw coal before such sulfur-extraction reaction, and coordinating control of water additions to such pulverant raw coal responsive to such moisture content analysis of the raw coal to provide moisture agglomerated pulverant work product for such sulfur-extraction reaction having a moisture content in the range of about 10% to 12.5% by weight. 17. The invention of claim 9 in which the rate o movement of work product through the conversion zone is con¬ trolled in .coordination with the controlled rate of movemen of work product through the sulfur-extraction to be greater than the rate of movement of work product through such sulfur-extraction έone. 18. The invention of claim 17 including predeterminedly establishing rate of movement of work product through such spray washing step to exceed delivery rate of work product from the conversion zone, such rate of movement of work product through such spray washing step being maintained at a rate independent of any variations in such controlled rate of movement of work product through such sulfur-extraction and conversion zones. 19. The invention of claim 1 including the steps of . analyzing the raw coal for sulfur content in per¬ centage by weight and, responsive to such sulfur content analysis, adding a hydrogen peroxide solution to such pulverant raw coal when the sulfur content exceeds 4% by weight. 20. Continuous-line operation apparatus for treatment of coal for extracting sulfur from the coal and for separating by-product containing the sulfur extracted from such coal, comprising in combination means for supplying pulverant raw coal for treat¬ ment, such pulverant coal having a sulfur content above 1.1% by weight, means for controllably adding calcium to such pulverant raw coal and controlling moisture level to provide a pulverant work product which is agglomerated by moisture, such calcium being added from the group consisting of lime and calcium hydroxide, a longitudinally-extended sulfur-extraction reaction zone defining an elongated travel path for the moisture agglomerated work product, such travel path being enclosed in extending between charge and discharge means for such work product, means for delivering such moisture agglomerated pulverant work product into such reaction zone, means for controlling rate of movement of the moisture agglomerated work product through such reaction zone, means for supplying a sulfur-extraction reactant including nascent oxygen, means for injecting such reactant into such reac¬ tion zone to provide contact with the moisture agglomerated work product during its movement along the elongated reac¬ tion zone travel path, means for quantitatively controlling injection of such reactant, such calcium additions to the pulverant raw coal being controlled to enable formation of calcium sulfate from sulfur extracted from the pulverant coal and to inhibit - E maintenance of sulfuric acid in the moisture agglomerated work product during passage through such reaction zone, spray washing means for directing pressurized spray wash containing water, means for conveying work product for spray washin during its movement along an elongated spray washing path t separate pulverant coal of decreased sulfur value from by¬ product containing sulfur extracted from such pulverant coal, and means for delivering such separated pulverant coal of decreased sulfur value. 21. The combination of claim 20 including means for treating such separated pulverant coal of decreased sulfur value to passivate surface sites from which sulfur has been extracted, and means for delivering such surface-passivated pulverant coal of decreased sulfur value. 22. The combination of claim 20 including means for pulverizing raw coal, and means for adding lime to such pulverizing means. 23. The invention of claim 20 in which the means for injecting reactant into such sulfur-extraction reaction zone includes means for injecting a sulfur-extraction gas dis¬ tributed along such reaction zone travel path with the reactant gas being injected into such reaction zone to provide a direction of impingement of such reactant gas with the moisture agglomerated ,work product- which is transverse to the direction of movement of such work product along such travel path. 24. The combination of claim 23 further including means for sensing temperature level in such reaction zone, and means for injecting quench cooling fluid into such reaction zone responsive to such sensed temperature level to prevent the temperature in such reaction zone from reaching steam formation levels. 25. The combination of claim 24 in which such quench cooling fluid injection means extends over at least a portion of such reaction zone travel path which is con¬ tiguous to such discharge means for gas treated work product 26. The combination of claim 20 including a longitudinally-extended conversion zone defining an elongated conversion travel path for work product which is enclosed in extending between charge and discharge means for such work product, means for delivering work product from the sulfur extraction reaction zone into such conversion zone, such delivery means being enclosed in extending from such reac¬ tion zone into such conversion zone, means for controlling rate of movement of work product through such conversion zone. means supplying a fluid conversion reactant, means for injecting s;uch conversion reactant into such conversion zone to provide contact with such work product during its movement along the elongated conversion zone travel path to convert calcium sulfate formed from sulfur extracted from such pulverant coal into by-product containing diammonium sulfate and calcium hydroxide, and in which such spray washing means separate the pulverant coal of decreased sulfur value from such by-product. 27. The combination of claim 26 in which such means for injecting conversion reactant includes injection outlets distributed longitudinally alon the elongated conversion zone travel path for injecting conversion reactant transversely to the direction of move¬ ment of work product along such elongated conversion zone travel path. 28. The invention of claim 21 in which such mean for passivation treatment of the pulverant coal of decrease sulfur value includes shell means establishing a longitudinally-extende passivation zone defining an elongated travel path which is enclosed in extending between charge means and discharge means for the separated pulverant coal of decreased sulfur value, means for delivering such pulverant coal of decreased sulfur value into such longitudinally extended passivation zone, and / means for injecting fluid passivation reactant distributed along the elongated passivation travel path for contact with particle surfaces of such pulverant coal during passage along such travel path. 29. The combination of claim 20 including means for analyzing raw coal for sulfur content, means for measuring the quantitative feed rate of such raw coal as delivered for treatment, and means for coordinating rate of movement of work product through such sulfur-extraction reaction zone and such controlled rate of injection of reactant into such sulfur-extraction reaction zone responsive to such sulfur content analysis of the raw coal. 30. The combination of claim 23 including means for analyzing the raw coal for moisture content percentage by weight, means for controllably adding wetting agent to such pulverant coal delivered for treatment, and means for controlling water additions to such pulverant coal in coordination with such moisture content analysis of the sulfur-contaminated coal to provide moistur agglomerated pulverant work product including calcium addi¬ tions having a desired moisture content for sulfur extrac¬ tion treatment. 31. The invention of claim 29 including means for coordinating the rate of movement of work product through such conversion zone with the rate of movement of work product through such sulfur-extraction zone. 32. The combination of claim 23 including means for analyzing raw coal for sulfur content in percentage by weight, and means for adding a hydrogen peroxide solution to such pulverant raw coal before sulfur-extraction treatment.

Inventors: CHAPPELL MARTIN L, CHINNICI ANTHONY J, GROVE F ALLEN, LARUE PHILIP R, CHAPPELL, MARTIN, L., CHINNICI, ANTHONY, J., GROVE, F., ALLEN, LARUE, PHILIP, R.
Applicants: CHAPPELL MARTIN L, CHINNICI ANTHONY J, GROVE ALLEN F, LARUE PHILIP R, CHAPPELL, MARTIN, L., CHINNICI, ANTHONY, J., GROVE, F., ALLEN, LARUE, PHILIP, R.
Application year: 1981
Main classification: C10L9
IPC codes: C10L9