Abstract: Cathodic protection voltages are used to resist the damage to pipes or cables from electrolytic effects. However, localised fields can lead to stray currents and may result in corrosion and it is therefore desirable to detect and analyse those stray currents. Frequently there are several pipes in the area of interest and so it is necessary to distinguish between those pipes. Therefore the cathodic voltage on the pipes is modulated, with different pipes having different modulations. This modulation may be applied using an interrupter. Orthogonal modulations with non-unitary aspect ratios improve the discrimination between the pipes whilst maximising the energy content of the modulation pattern. The analysis is improved when the interrupters are synchronised with each other and so repeating on the same time-base. This synchronisation may be achieved using an external time signal such as GPS. An interrupter which can be used in this regard is also proposed, and may be powered from the cathodic voltage itself.

Abstract: A method for reducing acid gas emissions from a carbonaceous fuel burning power plant. An aqueous potassium hydroxide dry scrubber method is used to reduce the formation of nitrogen oxides, sulfur oxides, hydrogen chlorides and hydrogen fluoride from plant flue gases. For those plants utilizing an electrostatic precipitator to remove particulate matter from the flue gas, the performance of this component is also enhanced by the injection of potassium hydroxide upstream of the component. As an added advantage, the final product has beneficial commercial utility as a fertilizer product, rather than having to be disposed in a landfill.

Abstract: A method for reducing NOx emissions from the combustion of carbonaceous fuels using two sequential stages of partial oxidation followed by a final oxidation stage. In the first stage, substoichiometric air condition of about 0.55 to 0.75 is used in a plug flow fashion, while second stage combustion is performed at a stoichiometric ratio of about 0.80 to 0.99. As the second stage combustion products are cooled by radiant heat transfer to the boiler furnace walls, overfire air is added to produce an stoichiometric ratio of about 1.05 to 1.25 to complete the combustion process. In this manner, the formation of thermal NOx is reduced.

Abstract: A method for reducing NOx emissions from the combustion of carbonaceous fuels using three stages of oxidation and second stage in-situ furnace flue gas recirculation. In the first stage, a partial oxidation combustor is used to partially combust the fuel in the presence of preheated combustion air. The fuel gas produced in the partial oxidation process is passed to a second stage partial oxidation combustor while molten slag is removed and disposed of. Preheated combustion air also is introduced into the second stage of combustion to produce a slightly reducing flue gas and is injected into the furnace in such a way as to create the desired in-situ furnace flue gas recirculation. In the upper part of the furnace a third combustion air is mixed with the flue gas in a third stage of combustion to substantially complete the combustion process. Preheated steam may be added to the first or second stages of combustion.

Abstract: Cathodic protection voltages are used to resist the damage to pipes or cables from electrolytic effects. However, localised fields can lead to stray currents and may result in corrosion and it is therefore desirable to detect and analyse those stray currents. Frequently there are several pipes in the area of interest and so it is necessary to distinguish between those pipes. Therefore the cathodic voltage on the pipes is modulated, with different pipes having different modulations. This modulation may be applied using an interrupter. Orthogonal modulations with non-unitary aspect ratios improve the discrimination between the pipes whilst maximising the energy content of the modulation pattern. The analysis is improved when the interrupters are synchronised with each other and so repeating on the same time-base. This synchronisation may be achieved using an external time signal such as GPS. An interrupter which can be used in this regard is also proposed, and may be powered from the cathodic voltage itself.

Abstract: A method and system for the use of waste coal fines to reduce nitrogen oxides emissions from a coal-fired cyclone boiler. A coal water slurry including waste coal fines is injected as a co-firing fuel into a cyclone barrel of the cyclone boiler to partially oxidize the coal water slurry in a central portion of the cyclone barrel where injected. This produces a reducing zone having reducing gas species that convert nitrogen oxides to diatomic nitrogen. The coal water slurry can alternatively be injected into the cyclone barrel from a secondary combustion air conduit. The evaporation of the water from the coal water slurry reduces the overall combustion temperature in the cyclone barrel, further reducing the production of nitrogen oxides.

Abstract: A method and apparatus for reducing NO.sub.x emissions from the combustion of carbonaceous fuels using three stages of oxidation. In the first stage, a partial oxidation combustor is used to partially combust the fuel in the presence of heated combustion air. The fuel gas produced in the partial oxidation process is passed to a second stage partial oxidation combustor while molten slag is removed and disposed of. A second preheated combustion air is introduced into the second stage combustor to produce a reducing flue gas. A third combustion air is mixed with the flue gas in a third stage combustor to substantially complete the combustion process. Preheated steam may be added at any or all of the combustion stages. The stochiometric ratios at each stage of combustion are controlled to minimize overall NO.sub.x emissions to acceptable levels.

Abstract: A method and system for the use of waste coal fines to reduce nitrogen oxides emissions from a coal-fired cyclone boiler. A coal water slurry including waste coal fines is injected as a co-firing fuel into a cyclone barrel of the cyclone boiler to partially oxidize the coal water slurry in a central portion of the cyclone barrel where injected. This produces a reducing zone having reducing gas species that convert nitrogen oxides to diatomic nitrogen. The coal water slurry can alternatively be injected into the cyclone barrel from a secondary combustion air conduit. The evaporation of the water from the coal water slurry reduces the overall combustion temperature in the cyclone barrel, further reducing the production of nitrogen oxides.

Abstract: A method and system is provided for the reduction of nitrogen and sulfur oxides emissions from carbonaceous fuel combustion flue gases. The method includes the injection of coal water slurry as a reburn fuel into furnace flue gases to partially oxidize the coal water slurry thereby producing reducing gas species in a reburn zone that convert flue gas nitrogen oxides to diatomic nitrogen. Optionally, sulfur oxides may also be removed from the flue gas by adding alkali compounds to the coal water slurry before injecting the slurry into the furnace, or by injecting the alkali compounds separately into the reducing reburn zone in the furnace created by the partial oxidation of the coal water slurry reburn fuel. The alkali compounds react with the sulfur species to produce alkali sulfite and sulfate particulate solids, which can be removed in a downstream particulate removal device such as an electrostatic precipitator or bag house.

Abstract: First, nitrogen oxides are reduced by firing coal in substoichiometric air conditions in a first stage oxidation unit of a combustor to reduce NO.sub.x from fuel bound nitrogen. Hydrated lime, Ca(OH).sub.2, is introduced into the first stage oxidation unit to produce calcium sulfide. The calcium sulfide becomes tied up in a slag eutectic which is removed prior to entry of the fuel gas to a second stage oxidation unit at the entrance of a furnace where additional preheated air is added to the fuel gas.

Abstract: The method of the present invention is a novel comprehensive process for maximizing the recovery of valuable mineral values from coal ash. Options may also be included for the production of saleable inorganic chemical by-products. The process employs both physical and chemical extraction techniques that maximize the yield of products while reducing the quantity of waste produced. Valuable minerals and chemicals such as cenospheres (hollow microspheres), carbon, magnetite (Fe.sub.3 O.sub.4), alumina (Al.sub.2 O.sub.3), iron oxide (Fe.sub.2 O.sub.3) and iron chloride (FeCl.sub.3) may be produced. Due to removal of carbon, magnetite, and iron oxide from the coal ash, the processed ash comprises a quality pozzolan.

Abstract: An improved fuel composition is provided comprising in minor proportion a non-dewatered sewage sludge and in major proportion an organic fuel comprised of a hydrocarbon fuel oil. A method is also provided for the incineration of sewage sludge comprised of providing an admixture of a minor proportion of a non-dewatered sewage sludge and a major proportion of an organic fuel comprised of a liquid hydrocarbon fuel oil and incinerating the admixture.

Abstract: A process for continuously gasifying wood, wood chips, wood charcoal, or other low-ash biomass material in a mechanically-ashed gasifier using a fixed bed gasification system to obtain a gaseous product relatively rich in carbon monoxide and hydrogen. Product gas comprising carbon monoxide, hydrogen, and carbon dioxide, together with methane and other diluents, is withdrawn from the gasification chamber. Sufficient noncombustible, particulate, refractory material is fed to the gasifier to provide an adequately deep layer of noncombustible solids on a moveable grate which supports the fuel bed, the object being to prevent damage to the grate and the grate-actuating mechanism caused by overheating, when the ash bed becomes too thin. The product gases from the gasification chamber may be used as raw synthesis gas for the production of, for example, methanol or as furnace heating gases.

Abstract: A novel method is provided for the production of anhydrous hydrofluoric acid from low-grade metallic fluorides using an intermediate aluminum fluoride compound. The method involves the reaction of low-grade metallic fluorides such as fluorspar with sulfuric acid to produce weak hydrofluoric acid. The weak acid is then reacted with a metallic salt (such as aluminum chloride) to form precipitated aluminum fluoride (AlF.sub.3.3H.sub.2 O). After dewatering, the aluminum fluoride is reacted with strong sulfuric acid to form aluminum sulfate and strong hydrofluoric acid.

Abstract: A method for desulfurization, denitrification, and oxidation, of carbonaceous fuels including a two stage oxidation technique. The carbonaceous fuel, containing ash, along with an oxygen-containing gas is introduced into a first stage partial oxidation unit containing a molten ash slag maintained at a temperature of about 2200.degree.-2600.degree. F. A flux may also be introduced into the first stage partial oxidation unit for the purpose of increasing the basicity and maintaining the viscosity of the molten ash slag at a value no greater than about 10 poise. The carbonaceous fuel is gasified, and sulfur is chemically bound and captured in the molten ash slag. Since the first stage is operated in a gasification mode (reducing atmosphere), essentially all of the nitrogen in the fuel is converted to diatomic nitrogen, which results in low nitrogen oxide emissions upon final combustion.

Abstract: An improved fuel composition is provided comprising in minor proportion a non-dewatered sewage sludge and in major proportion a particulate solid fuel. A method is also provided for the incineration of sewage sludge comprising providing a pumpable admixture of a non-dewatered sewage sludge and a particulate solid fuel and incinerating the admixture.

Abstract: A method for desulfurization and oxidation of carbonaceous fuels including a two stage oxidation technique. The carbonaceous fuel, along with an oxygen-containing gas is introduced into a first stage partial oxidation unit containing molten slag maintained at a temperature of about 2200.degree.-2600.degree. F. A flux may also be introduced into the first stage partial oxidation unit for the purpose of maintaining the viscosity of the molten slag at a value no greater than about 10 poise. The carbonaceous fuel is gasified, and sulfur is chemically bound and captured in the molten slag. The combustible gas derived from partial oxidation and gasification is directed along a substantially horizontal path to a second stage oxidation unit for final combustion. The sulfur-containing slag is removed to a water-sealed quench system for disposal.

Abstract: A continuous deep hydrogenation coal liquefaction process is disclosed wherein a slurry of powdered coal or other carbonaceous material in a recycle solvent is passed with hydrogen through a hydroextraction unit, the heavy coal extract remaining after removal of gas and oil is then fed into a low-temperature fluidized-bed pyrolysis unit, and the char and ash is fed from the pyrolysis unit to a high-temperature fluidized-bed char gasification unit. The gasification unit is specially constructed to provide continuous ash agglomeration and has a funnel-shaped grid plate at the bottom of the fluidized bed and an elutriation leg of reduced diameter at the bottom of the grid plate. Air or oxygen is introduced near the top of the elutriation leg to provide a high temperature such that the ash particles are continuously softened and caused to accrete or agglomerate in a hot spouting zone at the base of the grid plate.