Disclosed are methods and systems for removing submicron particles from a gas stream, in particular from urea prilling off-gas, wherein a Venturi ejector is used. A method comprises contacting a gas stream containing submicron particles in a Venturi ejector with an injected high velocity scrubbing liquid to provide a pumping action, wherein the scrubbing liquid has an initial velocity of at least 25 m/s and wherein the ratio of scrubbing liquid and gas flow is between 0.0005 and 0.0015 (m.sup.3/h)/(m.sup.3/h).

A method for removing ammonia from a gas stream divides the gas steam into a plurality of separate gas streams and sprays a dilute acid solution into the streams. The acid solution is aqueous sulfuric acid and ammonium sulfate is produced. A device is used to divide the gas stream, the device having a plurality of conduits in fluid communication with a plenum. Spray nozzles are located in each conduit to spray the acid solution into the gas streams. The device creates less than 10 Pa back pressure to the gas stream.

A method for removing ammonia from a gas stream divides the gas steam into a plurality of separate gas streams and sprays a dilute acid solution into the streams. The acid solution is aqueous sulfuric acid and ammonium sulfate is produced. A device is used to divide the gas stream, the device having a plurality of conduits in fluid communication with a plenum. Spray nozzles are located in each conduit to spray the acid solution into the gas streams. The device creates less than 10 Pa back pressure to the gas stream.

Systems and apparatuses for neutralizing acidic compounds in flue gases emitted from a heat recovery coke oven. A representative system includes a spray dry absorber having a barrel that includes a plurality of wall plates that form sidewalls of the barrel. The wall plates include a steel plate and a corrosion resistant alloy cladded to the steel plate and the wall plates are oriented such that the corrosion resistant alloy faces toward and is in fluid communication with an interior area of the barrel. The alloy is resistant to corrosion caused by the acidic compounds in the flue gas and can prevent the steel plate from being corroded by these acidic compounds.

Systems and apparatuses for neutralizing acidic compounds in flue gases emitted from a heat recovery coke oven. A representative system includes a spray dry absorber having a barrel that includes a plurality of wall plates that form sidewalls of the barrel. The wall plates include a steel plate and a corrosion resistant alloy cladded to the steel plate and the wall plates are oriented such that the corrosion resistant alloy faces toward and is in fluid communication with an interior area of the barrel. The alloy is resistant to corrosion caused by the acidic compounds in the flue gas and can prevent the steel plate from being corroded by these acidic compounds.

Systems and methods of producing a concentrated solution from a gas stream are disclosed. The method of producing a concentrate solution includes introducing the gas stream having the contaminant into an absorption chamber, introducing a dilute liquid having the contaminant into the absorption chamber, at least one of the gas stream and the dilute liquid being at an elevated temperature, and contacting the gas stream with the dilute solution to produce a liquid-enriched gas stream and a concentrate solution. The systems for producing a concentrated solution include a source of a gas stream having a contaminant, a source of a dilute solution having the contaminant, and an absorption chamber fluidly connected to the source of the gas stream and the source of the dilute solution. The source of the dilute solution can have a subsystem for removing contaminants from the gas stream, constructed and arranged to receive the gas stream or a liquid-enriched gas and produce the dilute solution.

Systems and methods of producing a concentrated solution from a gas stream are disclosed. The method of producing a concentrate solution includes introducing the gas stream having the contaminant into an absorption chamber, introducing a dilute liquid having the contaminant into the absorption chamber, at least one of the gas stream and the dilute liquid being at an elevated temperature, and contacting the gas stream with the dilute solution to produce a liquid-enriched gas stream and a concentrate solution. The systems for producing a concentrated solution include a source of a gas stream having a contaminant, a source of a dilute solution having the contaminant, and an absorption chamber fluidly connected to the source of the gas stream and the source of the dilute solution. The source of the dilute solution can have a subsystem for removing contaminants from the gas stream, constructed and arranged to receive the gas stream or a liquid-enriched gas and produce the dilute solution.

Provided is a method for using selective non-catalytic reduction to reduce nitrogen dioxide in exhaust gas generated during an olefin production process. Nitrogen dioxide generated in a catalyst regeneration step of a continuous PDH process can be efficiently removed by the method of the present disclosure. Ultimately, the generation of visible fumes can be prevented through the removal of nitrogen dioxide.

Provided is a method for using selective non-catalytic reduction to reduce nitrogen dioxide in exhaust gas generated during an olefin production process. Nitrogen dioxide generated in a catalyst regeneration step of a continuous PDH process can be efficiently removed by the method of the present disclosure. Ultimately, the generation of visible fumes can be prevented through the removal of nitrogen dioxide.

A contaminated gas stream can be passed through an in-line mixing device, positioned in a duct containing the contaminated gas stream, to form a turbulent contaminated gas stream. One or more of the following is true: (a) a width of the in-line mixing device is no more than about 75% of a width of the duct at the position of the in-line mixing device; (b) a height of the in-line mixing device is no more than about 75% of a height of the duct at the position of the in-line mixing device; and (c) a cross-sectional area of the mixing device normal to a direction of gas flow is no more than about 75% of a cross-sectional area of the duct at the position of the in-line mixing device. An additive can be introduced into the contaminated gas stream to cause the removal of the contaminant by a particulate control device.