A method for on-line continuous recovery of excess nitric acid in nitration reaction is provided. Nitration reaction liquid and nitrogen gas are simultaneously conveyed to a mixer, mixed and transferred to a temperature-controlled corrosion-resistant column for on-line continuous evaporation, where the nitration reaction liquid enters the temperature-controlled corrosion-resistant column from a top end, and the waste gas and excess nitric acid are discharged from a top port of the temperature-controlled corrosion-resistant column, and nitric acid is recovered. The nitric acid-free liquid is discharged from a bottom end of the temperature-controlled corrosion-resistant column by a pump.

A method for on-line continuous recovery of excess nitric acid in nitration reaction is provided. Nitration reaction liquid and nitrogen gas are simultaneously conveyed to a mixer, mixed and transferred to a temperature-controlled corrosion-resistant column for on-line continuous evaporation, where the nitration reaction liquid enters the temperature-controlled corrosion-resistant column from a top end, and the waste gas and excess nitric acid are discharged from a top port of the temperature-controlled corrosion-resistant column, and nitric acid is recovered. The nitric acid-free liquid is discharged from a bottom end of the temperature-controlled corrosion-resistant column by a pump.

A system for evacuating NO.sub.x gases from a nitric acid storage tank in a nitric acid production plant. The production plant includes a gas ejector with at least two gas inlets and at least one gas outlet, wherein a first gas inlet is branched from a gas conduit through which NO.sub.x-containing gas is flowing at a pressure P1 ranging from 2 to 16 bar; a second gas inlet is fluidically connected to the nitric acid storage tank essentially maintained at atmospheric pressure; and a gas outlet is fluidically connected to a gas conduit through which NO.sub.x-containing gas is flowing at a pressure P2 lower than P1. A method for evacuating NO.sub.x gases from a nitric acid storage tank, a method for revamping a system of a nitric acid plant, and the use of a gas ejector for evacuating NO.sub.x gases from a nitric acid storage tank in a production plant.

A system for evacuating NO.sub.x gases from a nitric acid storage tank in a nitric acid production plant. The production plant includes a gas ejector with at least two gas inlets and at least one gas outlet, wherein a first gas inlet is branched from a gas conduit through which NO.sub.x-containing gas is flowing at a pressure P1 ranging from 2 to 16 bar; a second gas inlet is fluidically connected to the nitric acid storage tank essentially maintained at atmospheric pressure; and a gas outlet is fluidically connected to a gas conduit through which NO.sub.x-containing gas is flowing at a pressure P2 lower than P1. A method for evacuating NO.sub.x gases from a nitric acid storage tank, a method for revamping a system of a nitric acid plant, and the use of a gas ejector for evacuating NO.sub.x gases from a nitric acid storage tank in a production plant.

A production plant for producing nitric acid at reduced power, the system being derived from a state-of-the art dual pressure nitric acid plant wherein the system further includes a first feature for splitting a tail gas stream into a first tail gas stream in fluid communication with compressed air and with an oxygen-rich gas and a second tail gas stream, and/or a feature for splitting a tail gas stream into a third tail gas stream in fluid communication with compressed air and with an oxygen-rich gas and a fourth tail gas stream. The production plant allows for reduction of power by the air compressor. A method for operating the system, the use of the system for performing the method, and a method for revamping a state-of-the-art dual pressure nitric acid plant into the system.

A production plant for producing nitric acid at reduced power, the system being derived from a state-of-the art dual pressure nitric acid plant wherein the system further includes a first feature for splitting a tail gas stream into a first tail gas stream in fluid communication with compressed air and with an oxygen-rich gas and a second tail gas stream, and/or a feature for splitting a tail gas stream into a third tail gas stream in fluid communication with compressed air and with an oxygen-rich gas and a fourth tail gas stream. The production plant allows for reduction of power by the air compressor. A method for operating the system, the use of the system for performing the method, and a method for revamping a state-of-the-art dual pressure nitric acid plant into the system.

A dual-pressure plant for the synthesis of nitric acid comprising: a reactor (4) providing a gaseous effluent (15) containing nitrogen oxides; an absorption tower (6) nitrogen oxides react with water providing raw nitric acid and, said absorption tower operating at a pressure greater than the pressure of the reactor; a compressor (5) elevating the pressure of the reactor effluent (15) to the absorption pressure; said plant also comprising a first bleacher (37) and a second bleacher (7), said first bleacher (37) stripping with air (39) nitrogen oxides from the output stream (27) of the absorption tower (6) providing a partially stripped nitric acid stream (40) and a nitrogen oxides-loaded air stream (41), the former being fed to the second bleacher (7) and the latter being recycled to the delivery-side of said compressor (5).

A dual-pressure plant for the synthesis of nitric acid comprising: a reactor (4) providing a gaseous effluent (15) containing nitrogen oxides; an absorption tower (6) nitrogen oxides react with water providing raw nitric acid and, said absorption tower operating at a pressure greater than the pressure of the reactor; a compressor (5) elevating the pressure of the reactor effluent (15) to the absorption pressure; said plant also comprising a first bleacher (37) and a second bleacher (7), said first bleacher (37) stripping with air (39) nitrogen oxides from the output stream (27) of the absorption tower (6) providing a partially stripped nitric acid stream (40) and a nitrogen oxides-loaded air stream (41), the former being fed to the second bleacher (7) and the latter being recycled to the delivery-side of said compressor (5).

A production plant for producing nitric acid at reduced power, the system derived from a state-of-the art mono pressure nitric acid plant wherein the system further includes a first feature for splitting a tail gas stream into a first tail gas stream in fluid communication with an oxygen-rich gas and with compressed air and a second tail gas stream, and/or a second feature for splitting a tail gas stream into a third tail gas stream in fluid communication with an oxygen-rich gas and with compressed air and a fourth tail gas stream, a feature for pressurizing a gas downstream the absorption tower. The production plant allows for reduction of power by the air compressor. A method for operating the system, the use of the system for performing the method of the disclosure, and a method for revamping a state-of-the art mono pressure nitric acid plant into the system.

A production plant for producing nitric acid at reduced power, the system derived from a state-of-the art mono pressure nitric acid plant wherein the system further includes a first feature for splitting a tail gas stream into a first tail gas stream in fluid communication with an oxygen-rich gas and with compressed air and a second tail gas stream, and/or a second feature for splitting a tail gas stream into a third tail gas stream in fluid communication with an oxygen-rich gas and with compressed air and a fourth tail gas stream, a feature for pressurizing a gas downstream the absorption tower. The production plant allows for reduction of power by the air compressor. A method for operating the system, the use of the system for performing the method of the disclosure, and a method for revamping a state-of-the art mono pressure nitric acid plant into the system.