A reactor for the synthesis of urea comprising a vertical shell and perforated baffles or trays (3) arranged to define compartments of the reactor, wherein each baffle comprises an array of individual perforated tiles (10) wherein each tile (101) comprises side walls (101A-101D) and a top face (101F), the side walls having first perforations for the liquid and said top face having second perforations for the gas, wherein said second perforations are smaller than said first perforations, and the tiles are distributed over the baffle with a two-dimensional pattern where adjacent tiles are separated by gaps (17).

A reactor for the synthesis of urea comprising a vertical shell and perforated baffles or trays (3) arranged to define compartments of the reactor, wherein each baffle comprises an array of individual perforated tiles (10) wherein each tile (101) comprises side walls (101A-101D) and a top face (101F), the side walls having first perforations for the liquid and said top face having second perforations for the gas, wherein said second perforations are smaller than said first perforations, and the tiles are distributed over the baffle with a two-dimensional pattern where adjacent tiles are separated by gaps (17).

A process for purifying a urea-containing aqueous stream, such as the aqueous stream from the recovery section of a urea plant, comprising a step of removing biuret from the urea-containing stream by reverse osmosis in one or more reverse osmosis stages.

A process for purifying a urea-containing aqueous stream, such as the aqueous stream from the recovery section of a urea plant, comprising a step of removing biuret from the urea-containing stream by reverse osmosis in one or more reverse osmosis stages.

A method for controlling discharges of nitrogen compounds in the production of cellulose carbamate (CCA). Microcrystalline cellulose is produced from chemical pulp produced at a pulp mill, such that the chemical pulp is subjected to acid hydrolysis at an elevated temperature to form microcrystalline cellulose (MCC) and hydrolysate, and the MCC is reacted with urea to produce cellulose carbamate whereby ammonia is released. The microcrystalline cellulose production and the cellulose carbamate production are integrated into the pulp mill having a flue gas system such that carbon dioxide from the flue gases is reacted with released ammonia to produce urea, which is used in the carbamate production.

A method for controlling discharges of nitrogen compounds in the production of cellulose carbamate (CCA). Microcrystalline cellulose is produced from chemical pulp produced at a pulp mill, such that the chemical pulp is subjected to acid hydrolysis at an elevated temperature to form microcrystalline cellulose (MCC) and hydrolysate, and the MCC is reacted with urea to produce cellulose carbamate whereby ammonia is released. The microcrystalline cellulose production and the cellulose carbamate production are integrated into the pulp mill having a flue gas system such that carbon dioxide from the flue gases is reacted with released ammonia to produce urea, which is used in the carbamate production.

There is provided a process and an apparatus for urea production in which preheating of raw material ammonia or heating in a medium-pressure decomposition step can be performed at a relatively low pressure while preventing decrease in an overall heat transfer coefficient. A process for urea production includes: a synthesis step of generating a urea synthesis solution; a high-pressure decomposition step of heating the urea synthesis solution to separate a gaseous mixture containing ammonia and carbon dioxide from the urea synthesis solution; a condensation step of condensing the gaseous mixture; a medium-low-pressure steam generation step of reducing a pressure of medium-pressure steam condensate obtained in the high-pressure decomposition step to a medium-low pressure to generate medium-low-pressure steam and medium-low-pressure steam condensate; and one or both of a medium-pressure decomposition step and an ammonia preheating step.

There is provided a process and an apparatus for urea production in which preheating of raw material ammonia or heating in a medium-pressure decomposition step can be performed at a relatively low pressure while preventing decrease in an overall heat transfer coefficient. A process for urea production includes: a synthesis step of generating a urea synthesis solution; a high-pressure decomposition step of heating the urea synthesis solution to separate a gaseous mixture containing ammonia and carbon dioxide from the urea synthesis solution; a condensation step of condensing the gaseous mixture; a medium-low-pressure steam generation step of reducing a pressure of medium-pressure steam condensate obtained in the high-pressure decomposition step to a medium-low pressure to generate medium-low-pressure steam and medium-low-pressure steam condensate; and one or both of a medium-pressure decomposition step and an ammonia preheating step.

A urea production process comprises a step of synthesis of urea by reaction of ammonia and carbon dioxide, where at least part of the carbon dioxide for the urea reaction synthesis is produced in an oxy-combustion process; the oxy-combustion process is specifically a flameless oxy-combustion process.

A urea production process comprises a step of synthesis of urea by reaction of ammonia and carbon dioxide, where at least part of the carbon dioxide for the urea reaction synthesis is produced in an oxy-combustion process; the oxy-combustion process is specifically a flameless oxy-combustion process.