Abstract: Methods and systems for producing a pressurized ammonia-containing gas stream from aqueous urea. The method comprising pumping an aqueous urea-containing solution to a fluid-tight enclosure at a rate to match the external demand for ammonia-gas, wherein a fluid heat transfer medium is applied to the exterior of the fluid-tight enclosure to transfer heat to the aqueous urea-containing solution sufficient to hydrolyze the solution to an ammonia gaseous product. The systems comprise means for carrying out the methods.

Abstract: A method for the selective control of the sulfur trioxide concentration in flue gases, to enhance the ash removal efficiency of electrostatic precipitators, which includes: catalytically converting a portion of the sulfur dioxide contained within the flue gas to sulfur trioxide, by passing a portion of such flue gas through at least one catalyst containing converter module which is positioned within such a flue gas stream; and selectively varying the quantity of flue gas passing through such module by providing an aspirating force to cause flue gas to be drawn through such a converter module.

Abstract: An apparatus for the selective control of the sulfur trioxide concentration in flue gases, to enhance the ash removal efficiency of electrostatic precipitators, which includes: catalytically converting a portion of the sulfur dioxide contained within the flue gas to sulfur trioxide, by passing a portion of such flue gas through at least one catalyst containing converter module which is positioned within such a flue gas stream; and selectively varying the quantity of flue gas passing through such module by providing an aspirating force to cause flue gas to be drawn through such a converter module.

Abstract: A method and apparatus for the selective control of the sulfur trioxide concentration in flue gases, to enhance the ash removal efficiency of electrostatic precipitators, which includes supporting a catalyst in the path of the flue gas, catalytically converting a portion of the sulfur dioxide contained within such flue gas to sulfur trioxide, by passing at portion of such flue gases over a catalyst which is positioned within the path; selectively varying the amount of sulfur trioxide produced by the catalytically converting, by selectively changing the quantity of flue gas flowing through such catalyst; and simultaneously maintaining the ratio of the pressure loss coefficient of the flue gas flowing through the other portion of such duct, in the vicinity of such catalyst, within a predetermined range.

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: Unburned particulate matter is removed from a combustion gas stream by adding a conditioning agent to modify the resistivity of the particulate matter and passing the conditioned combustion gas stream through an electrostatic precipitator whose precipitating elements are energized with an intermittent applied voltage. The addition of conditioning agent and the precipitating voltage signal are mutually optimized. A controller receives measurement signals from sensors that monitor the total flow rate of particulate matter in the gas stream before the electrostatic precipitation treatment, and the concentration of particulate matter in the gas stream after the treatment. Performance of the system may be optimized according to selected combinations of variables.

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 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: 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: A high voltage DC power supply including a high voltage transformer having output bushings extending from the transformer housing, and a rectifier unit mounted between the high voltage bushings. The rectifier unit is housed in an electrically nonconducting tank which contains a rectifier assembly immersed in an insulating liquid. The power supply has a common high voltage clearance space for both the transformer bushings and the rectifier unit.

Abstract: An apparatus and method for monitoring electrode rapper operation in an electrostatic precipitator. The actual movement or impact of the hammer in an electrode rapper is sensed and a control signal is generated and transmitted to a monitor in response thereto in order to produce an immediate and accurate indication of rapper failure.

Abstract: A gas conditioning means and more particularly a gas conditioning means incorporating an improved method of providing sulfur trioxide for injection into a flue gas stream.

Abstract: A gas cleansing apparatus and more particularly an electrostatic precipitating apparatus having improved discharge electrode means therein.