Abstract: Methods, systems, and apparatuses for anaerobic digestion of waste fibrous material and the recovery of nutrients are provided. Methods, systems, and apparatuses disclosed herein provide mechanisms to release dissolved gases from anaerobic digester effluent. Methods, systems and apparatuses disclosed herein can recover one or more nutrients from anaerobic digested effluent using a range of temperatures, aeration rates, aeration times, pH ranges, and settling times.

Abstract: A process for producing a usable product in a reactor comprising introducing co-reactants comprising a fuel source and oxygen into a first section through an inlet, the fuel source comprising carbon; combusting at least a portion of the fuel source and oxygen in an exothermic reaction in the first section using a burner; transferring the co-reactants through a second section that includes a throat having a size that is smaller than a size of the first section, such that a vacuum is induced and a velocity of the co-reactants increases; transferring the co-reactants into a third section that is downstream from the throat and includes an inner wall having a size that is greater than the size of the throat; depositing at least a portion of the uncombusted carbon and a metal oxide along the inner wall, wherein the metal oxide is introduced into at least one of the sections; converting the deposited metal oxide into the usable product in a carbothermic reduction reaction within a molten slag along the inner wall at

Abstract: A method for reducing mercury emission and/or re-emission in cleaned flue gas through control of sulfite concentration within a wet flue gas desulfurization (WFGD) system is disclosed. One method for reducing mercury emission and/or re-emission through control of sulfite concentration is to measure the sulfite concentration of an aqueous alkaline slurry used in a WFGD system and comparing the same to a predetermined sulfite concentration value. If the comparison reveals the measured sulfite concentration is above the predetermined values, the amount of oxidation air supplied to the system is increased. If the comparison reveals the measured sulfite concentration is below the predetermined values, the amount of oxidation air supplied to the system is decreased.

Abstract: Disclosed herein is a process and a plant for recovering ammonia from a mixture including ammonia, acid gas containing H2S and/or CO2 and low-boiling water-soluble organic components. To avoid an enrichment of volatile organic compounds in the acid gas absorber, a partial stream of the liquid phase is withdrawn from an acid gas absorber and processed such that gaseous ammonia with a reduced content of volatile organic components is obtained, which is recirculated into the acid gas absorber.

Abstract: Methods, systems, and apparatuses for anaerobic digestion of waste fibrous material and the recovery of nutrients are provided. Methods, systems, and apparatuses disclosed herein provide mechanisms to release dissolved gases from anaerobic digester effluent. Methods, systems and apparatuses disclosed herein can recover one or more nutrients from anaerobic digested effluent using a range of temperatures, aeration rates, aeration times, pH ranges, and settling times.

Abstract: An air pollution control system 10A according to the present invention includes: a boiler 11 that burns fuel; NOx removal equipment 12 that decomposes nitrogen oxides in flue gas 25 discharged from the boiler 11; a desulfurizer 15 that causes sulfur oxides in the flue gas 25 having passed through the NOx removal equipment 12 to be absorbed by an absorbent, thereby reducing sulfur oxides in the flue gas 25, a waste-water treatment device 16 including a solid-liquid separating unit 31 that separates desulfurized waste water 28 discharged from the desulfurizer 15 into a solid fraction and a liquid fraction, and a mercury removing unit 32 that removes mercury in the desulfurized waste water 28; and a treated waste-water returning unit (a makeup water line) 17 that returns at least a part of treated waste water 40 treated by the waste-water treatment device 16 to the desulfurizer 15.

Abstract: A process and apparatus for producing calcium sulfide is provided comprising a container housing one or more drums, each drum having a substantially horizontal longitudinal center axis and containing one or more screw conveyors therein. Multiple drums are connected by passageways, and passages are provided for passing material into and out of the container and the drum(s). A heater is provided for supplying heat to the material within the drum(s). The process comprises passing the reactants, gypsum and charcoal, into the container and drum(s), heating the reactants within the drum(s) thereby initiating a chemical reaction converting reactants to products (including calcium sulfide), moving the reactants and products substantially horizontally in the drum(s) through the use of the screw conveyor(s) contained therein, and passing the products out of the drum(s) and the container.

Abstract: In addition to ash and coke, the gasification residue contains alkaline earth metal sulfide and alkaline earth metal oxide because desulfuring agents have been supplied to the gasifier. At temperatures from 5.degree. to 80.degree. C. the gasification residue is mixed with an acid-containing aqueous solution so that a gas which is rich in H.sub.2 S is produced. Ash, coke, and alkaline earth metal salt are supplied to a flotation zone, in which coke is separated. A solid residue which contains ash and alkaline earth metal salt is withdrawn from the flotation zone. Carbonic acid or dilute sulfuric acid is preferably used as an acid.

Abstract: Disclosed is a method and an apparatus for the heat treatment of lime sludge (CaCO.sub.3) to form burnt lime (CaO). In the method of the present invention a lime sludge feed is entrained in and thereafter dried in a gas flash dryer means to produce a dried lime sludge. The dried lime sludge is separated from the gases and thereafter is fed to a rotary kiln in which the dried lime sludge is converted to active burnt lime. In order to maintain the flow of gas in the flash dryer means at a predetermined velocity in order to entrain all the lime sludge feed in the gas flow, an adjustable portion of the separated gases are recycled through the flash dryer means.

Abstract: A method for production of sulfur dioxide from calcium sulfate by high temperature thermal reduction. Calcium sulfate, preferably in the form of calcined phosphogypsum, is desulfurized using a fossil fuel as a heat source, the combustion products resulting therefrom being used as a reductant. The fuel and reductant may be coal, coke, liquid hydrocarbons or natural gas; high sulfur, medium or low rank coal is preferred. The fuel is combusted with air or oxygen-enriched air. The solid feeds are introduced as finely-divided particles entrained in reactant gases, and the temperature is sufficiently hot to cause residual processed materials to melt and drain from the reaction vessel in the form of a liquid slag, yet not hot enough to produce significant amounts of fine silicon oxide dust. Iron pyrite, sand and/or clay can be added to reduce the slag melting point and to control its viscosity.

Abstract: The present invention relates to the coproduction of a combustible gas stream usable as an energy source, a sulfur-dioxide-containing second gas stream usable as a source of oxidant in the gasification of coal, and a sulfur-dioxide-containing third gas stream usable as a feedstock for the production of sulfuric acid. The process includes heating coal in a coal gasification zone in the presence of an oxygen and sulfur dioxide-containing atmosphere under partial coal gasifying conditions to produce a carbonaceous char and a crude coal gas stream. Sulfur-containing compounds are removed from the coal gas stream and converted to elemental sulfur. The carbonaceous char is combined with gypsum to form a feed mixture. The non-gypsum portion of the feed mixture contains sufficient reducing potential to release substantially all of the sulfur in the gypsum as gaseous compounds of sulfur in a +4 or lower oxidation state.

Abstract: A pelletized mixture of gypsum, carbonaceous material and pyrite is charged to a travelling grate where the charge is heated under suitable conditions to produce a solid sintered material which has a broad spectrum of applications due to its chemical and physical properties and a gaseous effluent containing sulfur dioxide, sulfur or mixtures thereof.

Abstract: The invention relates to a process for the conversion of a calcium mineral into a calcium containing solid product and a gaseous stream which comprises subjecting the calcium mineral to a temperature in excess of about 3400 degrees Fahrenheit for less than one minute.

Abstract: The present invention relates to the coproduction of a combustible feed gas stream useable as an energy source and a sulfur-containing second gas stream useable as a feedstock for the production of sulfuric acid. The process includes heating coal in the presence of an oxygen-lean atmosphere under partial coal gasifying conditions to produce a solid carbonaceous char and a crude coal-gas stream. Sulfur-containing compounds are removed from the coal gas stream and converted to solid sulfur-containing materials. The solid sulfur-containing materials are combined with the solid carbonaceous char and gypsum to form a feed mixture. The non-gypsum portion of the feed mixture contains sufficient reducing potential to release substantially all of the sulfur in the gypsum as gaseous compounds of sulfur in a +4 or lower oxidation state. The feed mixture is heated under reducing conditions to produce a sulfur-containing second gas stream and a solid sintered product.

Abstract: In electrolytic production of magnesium metal the concentration of magnesium chloride in the bath is required to be replenished periodically or continuously. This magnesium chloride should be anhydrous and of certain specifications.This invention provides a method for the production of such anhydrous magnesium chloride in a two-stage dehydration of magnesium chloride solution, the first step consisting of preparation of a fine powder from magnesium chloride with 0.5 to 1.5 molecules of water and about 4 to 10% magnesium oxide with or without alkali or alkaline earth metal chlorides, or both depending on the starting material. This first step is carried out in a conventional apparatus like the spray drier, briquetting the above partially dehydrated product in admixture with carbon powder under pressure to obtain compacted material such as briquettes of bulk density of 0.6 to 1.3 g/c.c., and size 1.5 to 5 cm. Second step comprises heating the above briquettes to a temperature of 200.degree. to 350.degree. C.

Abstract: A method and apparatus for thermally reacting one or more inorganic materials, the method involves the step of maintaining a flame in a combustion chamber at a predetermined reaction temperature by supplying a sufficient quantity of a hydrocarbon fuel and oxygen into the flame through a fluid stream comminuting the inorganic materials to be reacted to a particle size which can be transported by gas flow and suspending the comminuted inorganic compound in an intimate admixture with the fluid stream containing the hydrocarbon fuel and oxygen and passing the admixture to the interior of the flame to effect thermal reaction of the particulate inorganic material. The apparatus can comprise a blower, a grinding means, a furnace means, and a means for collecting the reacted material.

Abstract: Phosphogypsum is mixed with fine coal, balled, and charged to a travelling grate where the charge is heated under reducing conditions to evolve sulfur and/or sulfur dioxide for conversion into sulfuric acid.

Abstract: Fuel is passed (via line 13) to a fluidized fuel conversion bed (21) containing reactive CaO and CaSO.sub.4 at a fuel-oxidation temperature (e.g. 730.degree. C.) below the temperature at which CaO reacts with CO.sub.2 to form CaCO.sub.3. The bed is fluidized by an inerts-free gas containing hydrogen (and/or a source thereof, e.g. steam) and fuel is therein partially oxidized, CaSO.sub.4 being reduced to CaS. CO.sub.2 thus formed is fixed as CaCO.sub.3, and bed solids containing CaS and CaCO.sub.3 pass (via 33) to a fluidized decarbonation bed (34) operated at a temperature (e.g. 850.degree. C.) above the decarbonation temperature of CaCO.sub.3 whereby CO.sub.2 is liberated and is recovered after passage through a heat recovery device (6). The decarbonation bed (34) is preferably fluidized by the gas products from the fuel conversion which reduce CaSO.sub.4 therein to CaS and form additional CO.sub.2.

Abstract: Process for the burning of lime, cement or other lumpy bulk materials in a shaft kiln using coal. Coal dust or particulated dry coal is continuously fed into a gasification chamber positioned in the center of the shaft kiln and is therein partially or fully gasified by the addition of air in substoichiometric proportions. The partially or fully gasified fuel is mixed with air at an elevated temperature. Such mixture is then burned in the burning zone of the shaft kiln. The flow of the heating medium, i.e., the burnt fuel, and the flow of the kiln charge are co-current within the kiln. The shaft kiln has a centrally postioned gasification chamber which is mounted on radial supports which are positioned in the shaft kiln in such a way as to produce a space below the supports. The space is substantially free from kiln charge. Uniform distribution of the gases is guaranteed across the cross section of the shaft kiln by the space.

Abstract: Calcium sulfate is decomposed to CaO and SO.sub.2 by high temperature treatment in a fluidized bed wherein reductive and oxidative conditions are simultaneously maintained. A highly reducing gas is formed in the lower portion of the bed from partial combustion of the fuel in admixture with the primary fluidizing air. The quantity of the primary fluidizing air is limited so that the reducing conditions in the lower zone converts the CaSO.sub.4 to a mixture of CaO and CaS. Secondary air is introduced at a higher level in the bed to create an oxidizing zone in the upper portion of the bed above the reducing zone capable of converting CaS to CaO. The concurrent use of such reducing and oxidizing zones permits reducing conditions to be maintained which favor a high rate of decomposition even though these conditions favor the formation of CaS as well as CaO.

Abstract: Pellet-shaped calcium hydroxide forming part of the mixture of flux and ores in electrothermal calcium carbide furnaces is calcined. The pellets are made by granulating or briquetting moist calcium hydroxide, delivered to a sintering grate and conveyed thereon through a heating zone, wherein high temperatures are produced by the combustion of gas, above the grate, and wherein the combustion gas is exhausted, below the grate. The calcium hydroxide pellets are more especially placed on to the grate, covered with a layer of broken limestone and the undried pellets are directly conveyed through the heating zone, in an apparatus for carrying out the process.