Disclosed is a method for the removal of soluble particulate matter from a gas stream, such as urea dust from the off-gas of a finishing section of a urea production plant. The method comprises subjecting the off-gas to at least two quenching stages an aqueous quenching liquid. The quenching liquid used in a first, upstream quench stage, is allowed to have a higher concentration of dissolved particulate matter than the quenching liquid in the second, downstream quench stage. The quenched gas is led through a particle capture zone, typically comprising one or more of a wet scrubber, a Venturi scrubber, and a wet electrostatic precipitator.

A method for removing noxious, hazardous, toxic, mutagenic, and/or carcinogenic compounds and/or precursor compounds from a comingled gas, liquid, and/or solid stream is described. In one embodiment, the method is used to prepare the stream for feeding to an oxidizer, such as a thermal oxidizer, to reduce the amount of particulate matter discharged by the oxidizer and includes passing the stream through an ambient or chilled temperature condenser followed by an optional gas/solid separator, and one or more gas scrubbers prior to feeding to the oxidizer.

The present invention relates generally to the generation of steam via the use of a combustion process to produce heat and, in one embodiment, to a device, system and/or method that enables one to control one or more process parameters of a combustion process so as to yield at least one desirable change in at least one downstream parameter. In one embodiment, the present invention is directed to a system and/or method for controlling at least one process parameter of a combustion process so as to yield at least one desirable change in at least one downstream process parameter associated with one or more of a wet flue gas desulfurization (WFGD) unit, a particulate collection device and/or control of additives thereto and/or a nitrogen oxide control device and/or control of additives thereto and/or additives to the system.

An electrostatic precipitator for removing particulates from boiler flue gas, the electrostatic precipitator comprising: discharge electrodes and collecting electrodes fitted in a gas passage, said electrodes being arranged in at least two electrical fields that are placed successively in relation to gas flow, the electrical field establishing at least one electrical unit in transversal direction of said gas passage, the electrical unit constituting a portion of the precipitator having ability to be de-energised independently, separately from the other electrical units of the electrostatic precipitator. The first electrical field of said at last two electrical fields is arranged to be first in said gas flow. The first electrical field comprises more electrical units than a second field following said first field.

A waste gas is contacted with a mercury removal agent to remove mercury and a flue gas conditioning agent to alter a resistivity and/or cohesivity of particulates. The flue gas conditioning agent can be substantially free of SO.sub.3 and/or comprise more than about 25 wt. % SO.sub.3, and/or the mercury removal agent can be substantially unaffected by the flue gas conditioning agent. An amount of mercury removed from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent. An amount of the acid gas removed, by an acid gas removal agent, from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent.

A waste gas is contacted with a mercury removal agent to remove mercury and a flue gas conditioning agent to alter a resistivity and/or cohesivity of particulates. The flue gas conditioning agent can be substantially free of SO.sub.3 and/or comprise more than about 25 wt. % SO.sub.3, and/or the mercury removal agent can be substantially unaffected by the flue gas conditioning agent. An amount of mercury removed from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent. An amount of the acid gas removed, by an acid gas removal agent, from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent.

A waste gas is contacted with a mercury removal agent to remove mercury and a flue gas conditioning agent to alter a resistivity and/or cohesivity of particulates. The flue gas conditioning agent can be substantially free of SO.sub.3and/or comprise more than about 25 wt. % SO.sub.3, and/or the mercury removal agent can be substantially unaffected by the flue gas conditioning agent. An amount of mercury removed from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent. An amount of the acid gas removed, by an acid gas removal agent, from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent.

A waste gas is contacted with a mercury removal agent to remove mercury and a flue gas conditioning agent to alter a resistivity and/or cohesivity of particulates. The flue gas conditioning agent can be substantially free of SO.sub.3and/or comprise more than about 25 wt. % SO.sub.3, and/or the mercury removal agent can be substantially unaffected by the flue gas conditioning agent. An amount of mercury removed from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent. An amount of the acid gas removed, by an acid gas removal agent, from the waste gas in the presence of the flue gas conditioning agent can be the same or more than that removed from the waste gas in the absence of the flue gas conditioning agent.

Various embodiments address removal of one or more species from a gas stream by exposing the gas stream to divided portions of a fluid, such as droplets of water or mist, where the fluid, and/or content of the fluid, can absorb or modify the species and thereby remove it at least partially from the gas stream. Removal of CO2 from a combustion exhaust stream is one embodiment.

Various embodiments address removal of one or more species from a gas stream by exposing the gas stream to divided portions of a fluid, such as droplets of water or mist, where the fluid, and/or content of the fluid, can absorb or modify the species and thereby remove it at least partially from the gas stream. Removal of CO2 from a combustion exhaust stream is one embodiment.