A process for reducing nitrogen oxides in an exhaust stream, such as a vehicle exhaust stream, and apparatus for carrying out the process. The process comprises providing a first composition comprising aqueous urea, a second composition comprising ammonium carbamate and an exhaust stream comprising nitrogen oxides. A process for producing the ammonium carbamate is also provided. The second composition may be introduced into the exhaust stream (10) when the exhaust stream has a temperature below a threshold temperature and the first composition may be introduced into the exhaust stream when the exhaust stream has a temperature at or above the threshold temperature.

An integrated process for the production of a formaldehyde-stabilised urea is described comprising the steps of: (a) generating a synthesis gas comprising hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam in a synthesis gas generation unit; (b) dividing the synthesis gas into a first synthesis gas stream and a smaller second synthesis gas stream; (c) subjecting the first synthesis gas stream to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (d) cooling the shifted gas to below the dew point and recovering condensate to form a dried shifted gas; (e) recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas; (f) subjecting the carbon dioxide-depleted synthesis gas to a stage of methanation in one or more methanation reactors to form an ammonia synthesis gas; (g) synthesising ammonia from the ammonia synthesis gas in an ammonia production unit and recovering the ammonia; (h) reacting a portion of the ammonia and at least a portion of the recovered carbon dioxide stream in a urea production unit to form a urea stream; and (i) stabilising the urea by mixing the urea stream and a stabiliser prepared using formaldehyde to form a stabilised urea, wherein the formaldehyde is generated by steps comprising; (1) passing the second portion of synthesis gas through a scrubber to remove contaminants therefrom and form a scrubbed synthesis gas; (2) synthesising methanol from the scrubbed synthesis gas in a methanol synthesis unit, and recovering the methanol and a methanol synthesis off-gas; (3) combining the methanol synthesis off-gas with the shifted gas and (4) subjecting at least a portion of the recovered methanol to oxidation with air in a formaldehyde stabiliser production unit to produce formaldehyde.

An integrated process for the production of a formaldehyde-stabilised urea is described comprising the steps of: (a) generating a synthesis gas comprising hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam in a synthesis gas generation unit; (b) dividing the synthesis gas into a first synthesis gas stream and a smaller second synthesis gas stream; (c) subjecting the first synthesis gas stream to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (d) cooling the shifted gas to below the dew point and recovering condensate to form a dried shifted gas; (e) recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas; (f) subjecting the carbon dioxide-depleted synthesis gas to a stage of methanation in one or more methanation reactors to form an ammonia synthesis gas; (g) synthesising ammonia from the ammonia synthesis gas in an ammonia production unit and recovering the ammonia; (h) reacting a portion of the ammonia and at least a portion of the recovered carbon dioxide stream in a urea production unit to form a urea stream; and (i) stabilising the urea by mixing the urea stream and a stabiliser prepared using formaldehyde to form a stabilised urea, wherein the formaldehyde is generated by steps comprising; (1) passing the second portion of synthesis gas through a scrubber to remove contaminants therefrom and form a scrubbed synthesis gas; (2) synthesising methanol from the scrubbed synthesis gas in a methanol synthesis unit, and recovering the methanol and a methanol synthesis off-gas; (3) combining the methanol synthesis off-gas with the shifted gas and (4) subjecting at least a portion of the recovered methanol to oxidation with air in a formaldehyde stabiliser production unit to produce formaldehyde.

A method for the production of a urea ammonium sulphate (UAS) composition in a pipe reactor comprising at least a reactor section, the method comprising: combining in the reactor continuous feeds of at least one of sulphuric acid and ammonium bisulphate, at least one of ammonia and ammonium carbamate, and urea; and including a viscosity-reducing agent selected from water soluble aluminum salts in at least one of the continuous feeds, thereby forming the urea ammonium sulphate (UAS composition, wherein the UAS composition comprises 1 to 40 weight % of ammonium sulphate (AS) relative to the total weight of the UAS composition.

A method for the production of a urea ammonium sulphate (UAS) composition in a pipe reactor comprising at least a reactor section, the method comprising: combining in the reactor continuous feeds of at least one of sulphuric acid and ammonium bisulphate, at least one of ammonia and ammonium carbamate, and urea; and including a viscosity-reducing agent selected from water soluble aluminum salts in at least one of the continuous feeds, thereby forming the urea ammonium sulphate (UAS composition, wherein the UAS composition comprises 1 to 40 weight % of ammonium sulphate (AS) relative to the total weight of the UAS composition.

Disclosed are: a treatment method comprising (1) a step in which an aqueous solution containing urea, ammonia and carbon dioxide is introduced into a first stripper (PCS1) and subjected to stripping, and the aqueous solution after stripping is introduced into a urea hydrolyzer (UHY), (2) a step in which urea in the aqueous solution is hydrolyzed in the urea hydrolyzer (UHY), and the aqueous solution after hydrolysis is introduced into a second stripper (PCS2), (3) a step in which the aqueous solution is subjected to stripping in the second stripper (PCS2), and (4) a step in which a part of the aqueous solution before being stripped in the first stripper (PCS1), and/or, a part of the aqueous solution after being stripped in the first stripper (PCS1) but before being hydrolyzed in the urea hydrolyzer (UHY) is introduced into an exhaust gas treatment equipment equipped with an ammonia scrubbing equipment (ASCR); and a treatment equipment therefor.

An installation for the production of granular urea, having at least one urea granulator, at least one dust scrubber, at least one concentrating device, and at least one condensation device, wherein an exhaust gas flow from the urea granulator can be fed to the dust scrubber, wherein the exhaust gas flow is washed in the dust scrubber, wherein at least one outflow from the dust scrubber can be fed to the concentrating device, wherein the outflow can be concentrated in the concentrating device, wherein the vapors created during concentration can be fed, at least in part, to the condensation device, and wherein the vapors are at least partially condensed in the condensation device.

Disclosed is a method for the removal of urea dust from the off-gas of a finishing section of a urea production plant. the method comprises subjecting the off-gas to quenching with water so as to produce quenched off-gas, and subjecting the quenched off-gas to scrubbing using at least one venturi scrubber. As a result, a lower pressure drop over the scrubber is attained, and a more efficient growth of urea particles, facilitating the removal thereof.

Disclosed is a method for the removal of urea dust from the off-gas of a finishing section of a urea production plant. the method comprises subjecting the off-gas to quenching with water so as to produce quenched off-gas, and subjecting the quenched off-gas to scrubbing using at least one venturi scrubber. As a result, a lower pressure drop over the scrubber is attained, and a more efficient growth of urea particles, facilitating the removal thereof.

A urea preparation machine includes a cabinet, a stirring tank, a filtering portion, a water tank portion and a heating portion. The stirring tank is provided in the cabinet. The filtering portion is provided in the cabinet. An inlet of the water tank portion s communicated with an outlet of the filtering portion. The heating portion is provided in the cabinet, the heating portion is communicated with the outlet of the water tank portion, and an outlet of the heating portion is communicated with the stirring tank. The independent heating portion is used for heating water in the water tank portion, then the water heated by the heating portion is conveyed to the stirring tank for preparing urea, through such installation, the heating portion is capable of heating the water in the water tank portion in time.