Abstract: A hot-side electrostatic precipitator removes particulate matter from a NOX-containing flue gas stream passing therethrough, the exit flue gas stream having a temperature of no less than about 450F. The precipitator contains a plurality of collecting surfaces arranged in a series of fields. At least some of the collecting surfaces carry a catalyst which promotes a reaction between NOX in the flue gas passing therethrough and a nitrogeneous compound. Preferably, a nitrogeneous compound such as ammonia is electrically charged and injected into the flue gas stream prior to its passing over the collecting surfaces coated with catalyst. The hot-side electrostatic precipitator may have catalyst coated onto fixed surfaces near its exit end.

Abstract: The NOx content in a flow of flue gas is reduced by passing the flue gas through a first treatment zone and a second treatment zone. A nitrogeneous treatment agent is introduced into the first treatment zone for the selective non-catalytic reduction of part of the NOx, and the flue gas is thereafter passed through the second treatment zone which includes a catalyst for further selective catalytic reduction of the NOx. Optionally, a second nitrogeneous treatment agent is added to the flue gas in the second treatment zone. The quantity of NOx in the flue gas is detected intermediate the first and second treatment zones and, optionally, after the flue gas has left the second treatment zone. The quantity of ammonia in the flue gas exiting from the second treatment zone is also detected. The amounts of the treatment agents added to the flue gas are controlled responsive to the variations and absolute levels determined by these measurements.

Abstract: The volumetric flow rate for the addition of a flue gas conditioning agent, such as sulfur trioxide, is established by maintaining the derivative of the electrostatic precipitator power with respect to flow rate within a preselected operating range. The derivative of the precipitator power with respect to time and the derivative of the flow rate with respect to time are measured, and then the derivatives are divided to determine the derivative of precipitator power with respect to flow rate. This calculated value is compared with a preselected operating range. If the calculated value is greater than the preselected operating range, the flow rate of the conditioning agent is increased. If the calculated value is less than the preselected operating range, the flow rate is reduced, until a steady state calculated derivative value within the operating range is reached.

Abstract: Additions of conditioning agents to a particulate-containing flue gas stream are controlled by a controller operating from feedforward and feedback signals received from sensors in the combustion and gas cleanup system, and, optionally, from the power consumption level of the electrostatic precipitator. The flow rates of the conditioning agents, such as sulfur trioxide and ammonia, are thereby balanced to achieve an optimal removal of particulate matter and also sulfur and sulfur compounds from the gas stream before it is exhausted to the atmosphere. A typical feedforward signal is the boiler loading, and typical feedback signals include residual sulfur trioxide and ammonia levels and stack gas opacity.

Abstract: The sulfur trioxide in the combustion gas stream of a power plant is reacted with injected ammonia to produce a solid ammonium sulfate that is captured, and not released to the atmosphere. A feedforward signal indicative of the total mass flow of sulfur trioxide is determined as the product of the measured boiler load and the sulfur trioxide content of the combustion gas, as measured prior to the addition of ammonia. The ammonia mass flow injection rate is preferably at a normal stoichiometric ratio of from about 1.0 to about 1.1 relative to the sulfur trioxide mass flow rate (that is, from about 2.0 to about 2.2 times the molar mass flow rate of the sulfur trioxide), avoiding the production of ammonia bisulfate. The ammonia content of the combustion gas stream is measured downstream of the location at which ammonia is added.

Abstract: The resistivity of particulate matter in a gas stream, such as a combustion gas stream produced in a coal-fired power plant, is measured by collecting a sample of the particulate on the surface of a porous ceramic cylinder, either with or without an applied collection voltage, and then determining the resistance of the sample with a compound measurement electrode having multiple conductors. The reference electrode and the measurement electrode are spirally wound on the ceramic cylinder in an interdigitated manner, so that the two are laterally adjacent down the length of the cylinder. The pressure within the cylinder is controllable, with a pressure below atmospheric being applied to draw the particulate to the suface and ascertain when a sufficient sample for measurement is present, and a pressure above atmospheric being applied to blow away the sample after the measurement is completed, thereby preparing the instrument for the taking of another sample.

Abstract: Effluent gas streams from power plants, or other sources, containing entrained particulate matter are conditioned by injecting a conditioning gas such as sulfur trioxide into the flowing gas stream. The conditioning gas is deposited upon the surface of the particulate and reduces its electrical resistivity, improving the performance of electrostatic precipitators through which the flowing gas is passed to precipitate the particulate. At the point of injection, an electrostatic potential is established between the particulate in the flowing gas stream and the conditioning gas molecules, so that the conditioning gas is attracted to the particulate. Interaction of the conditioning gas with the particulate is stronger and more rapid than in the absence of the electrostatic potential at the point of injection.

Abstract: The invention relates to an injection probe, particularly for the sulfur trioxide conditioning of flue gasses, comprising a tubular, closed-end outer casing, a manifold connected to a feed conduit and provided with radially projecting injector tubes, the ends of which project through openings in the outer casing, being disposed within the casing and at least partially surrounded by an insulating material, and a mounting flange connected to the outer casing for attachment of the injection probe. In a known injection probe of this type, employed for injecting sulfur trioxide at a high temperature into a flue gas stream having a lower temperature, there occur considerable heat losses between the supply inlet end of the injection probe and the ends of the injector tubes, resulting in damage to the injection probe, undesirable sedimentation and unsatisfactory operation.

Abstract: A gas conditioning apparatus for conditioning flue gases and more particularly an improved means for purging a gas conditioning system of latent or residual sulfur trioxide which is normally produced by the gas conditioning system for conditioning of flue gases.

Abstract: A method and apparatus for providing a pulse-generating control to energize the electrodes of an electrostatic precipitator which includes means for producing a voltage between the electrodes of the precipitator after a voltage pulse has been applied to the precipitator electrodes which is higher than the voltage existing between the electrodes prior to the application of the voltage pulse and which voltage pulses are repeated until a preselected voltage is achieved between the electrodes.

Abstract: A gas conditioning means for a plurality of boilers and more particularly an improved means for providing a conditioning mixture of sulfur trioxide (SO.sub.3), from a single system, for injection into the flue gas streams of a plurality of boilers for the conditioning thereof.

Abstract: A railway freight truck bolster friction assembly and more particularly improved friction assemblies of elastomeric material which are adapted to be captively retained intermediate an axial end portion of a boltster member and an adjacent side frame.

Abstract: A vibratory wire strain gage and more particularly a vibratory wire strain gage having an improved means for readily tensioning the gage wire and, if desired, adjusting such tension prior to installation.

Abstract: A hot strip rolling mill stand, and more particularly a mill stand for use in the hot rolling process of a continuous strip casting system for aluminum, aluminum alloys and other metals, and which includes an improved means for the discrete applications of coolant for cooling rolls and to maintain thermostability and also for applying direct application lubricant for the strip being reduced.

Abstract: A therapist's patient evaluation and training device and more particularly such a device for evaluating disorders of brain damaged patients and of patients who have suffered trauma to or disease of the central nervous system and for aiding such patients in obtaining confidence to overcome such deficiencies to the utmost of their respective residuary capacities.

Abstract: An airborne stores arming trigger unit and more particularly an arming trigger unit used in conjunction with bombs and the like which are carried by military aircraft and which arming trigger unit includes improved means for better insuring an unarmed drop of bombs from such aircraft.

Abstract: A railway freight truck bolster friction assembly and more particularly improved friction assemblies of elastomeric material which are adapted to be captively retained intermediate an axial end portion of a bolster member and an adjacent side frame.

Abstract: A hydraulic snubber device and more particularly, a snubber adapted to be interposed between a bolster and a side frame member and being operative to provide a first damping rate when the railway car is operating on tangent track and at equilibrium speed on super elevated track and to provide a second relatively higher damping rate when the railway car is operating on super elevated track at low speed and in all instances of severe rocking.

Abstract: An industrial sulfur trioxide (SO.sub.3) gas injection probe and method of manufacture, and more particularly an SO.sub.3 gas injection probe for injecting SO.sub.3 into a gaseous stream having improved structural and insulating characteristics and a simplified method of manufacture.

Abstract: An apparatus for railway freight car control including a damping device adapted to be interposed between a bolster end and side frame member in a manner that the longitudinal axis thereof is inclined inwardly towards the swing axis of the side frame thus providing for a combined control effect for hunting and swaying.