A cryogenic air separation unit that provides flexibility in the production of liquid products is disclosed. The present cryogenic air separation unit and associated operating methods involves the use of a dual nozzle arrangement for the main heat exchanger that allows a turbine air stream draw from the main heat exchanger at different temperatures to provide refrigeration to the cryogenic air separation unit which, in turn, enables different production modes for the various liquid products.

An air separation unit comprises: a first waste gas control valve which is provided in a first waste gas pipe; a first waste gas flow rate control unit which measures a gas flow rate in the first waste gas pipe and adjusts a degree of opening of the first waste gas control valve so that a measured value which has been measured reaches a preset first waste gas flow rate set value; a second waste gas control valve which is provided in a second waste gas pipe; a regeneration gas flow rate control unit which measures the gas flow rate in a regeneration gas pipe and outputs a first output value based on a measured value which has been measured and a preset regeneration gas flow rate set value; and a control unit which uses, as a target set value of the flow rate of a second waste gas, a value obtained by subtracting the first waste gas flow rate set value of the first flow rate measuring unit from the flow rate set value of the regeneration gas flow rate, compares the first output value with a second output value based on a value obtained by subtracting the measured value of the first flow rate control unit from the measured value of the regeneration gas flow rate control unit, controls the degree of opening of the second waste gas control valve on the basis of the lower of the values, and adjusts the second waste gas flow rate.

An air separation device can include: a first compressor and a second compressor for compressing feed air; a first refrigerator and a second refrigerator for cooling the feed air; a pre-purification unit for pre-purifying the feed air; a flow rate measuring unit for measuring the flow rate of the feed air; a main heat exchanger for subjecting the feed air to heat exchange; a purification portion into which the feed air led out from the main heat exchanger is fed, and which separates and purifies product nitrogen and/or product oxygen from the feed air; and a compressor control unit for controlling the feed quantity of the feed air in accordance with an increase or decrease in the production quantity of product nitrogen and/or product oxygen.

A method for the production of air gases by the cryogenic separation of air can include the steps of sending a purified and compressed air stream to a cold box under conditions effective for cryogenically separating the air stream into oxygen and nitrogen using a system of columns, wherein the purified and compressed air stream is at a feed pressure when entering the system of columns; withdrawing the oxygen at a product pressure; delivering the oxygen at a delivery pressure to an oxygen pipeline, wherein the oxygen pipeline has a pipeline pressure; and monitoring the pipeline pressure. The method can also include a controller configured to determine whether to operate in a power savings mode or a variable liquid production mode. By operating the method in a dynamic fashion, a power savings and/or additional high value cryogenic liquids can be realized in instances in which the pipeline pressure deviates from its highest value.

A chiller can be configured as a chiller for a gasification system or other type of system or plant. In some embodiments, the chiller can be configured to utilize a single heat source, such as low grade waste heat in the form of hot water, and/or low pressure steam to drive one or more absorption-based chillers to cool inlet air to one or more adsorbers of a pre-purification unit (PPU). In the event of the detection of an undesired impurity spike (e.g. carbon dioxide spike, etc.) an additional amount of heat source can be withdrawn from the gasification system to increase the level of cooling the absorption chiller can provide to improve the removal of impurities. An automated control loop can be utilized in some embodiments. The control loop can be configured to check for an impurity concentration and adjust operations accordingly.

An apparatus for separation of air by cryogenic distillation comprising: a system of columns; a first turbine; a warm compressor coupled to the first turbine; a second turbine; a cold compressor coupled to the second turbine; a heat exchanger; means for sending air cooled in the heat exchanger at an intermediate temperature of the heat exchanger to the cold compressor; means for sending expanded air from the second turbine to the system of columns; means for sending air compressed in the cold compressor to an intermediate point of the heat exchanger and then at least in part to the system of columns via a first valve; means for sending air compressed in the cold compressor to the inlet of the first turbine via a second valve without passing through the heat exchanger, wherein the means for sending air compressed in the cold compressor to the inlet of the first turbine via the second valve without passing through the heat exchanger is also connected to the inlet of the first turbine; means for sending a fraction of air cooled in the heat exchanger to an intermediate temperature of the latter to the first turbine; means for sending expanded air from the first turbine to the system of columns; and a bypass line provided with an expansion valve configured to send air from the cold compressor to the system of columns without passing through the heat exchanger.

Method for separating air by cryogenic distillation in an air separation device comprising a system of columns, a first turbine and a second turbine, wherein, in de-icing operation, a common duct bringing air from the two turbines to a column is closed by means of an isolation valve, a purge gas is sent to the turbines at a temperature above 0 C. in order to de-ice them, but purge gas is not sent to the system of columns.

Method for separating air by cryogenic distillation, wherein at least part of the air to be distilled is boosted in an air booster, compressed air is allowed to expand in at least one expansion turbine and, if the pressure drop between two points of the booster passes under a threshold and/or a flow of the booster passes under a minimum flow of the booster, part of the air boosted in the booster is allowed to expand without having been cooled between the booster and the expansion turbine and the boosted expanded air is sent upstream or downstream of the at least one turbine, without having been cooled in the heat exchanger, after having been boosted.

Method for separating air by cryogenic distillation, wherein air is compressed in a compressor and is subsequently sent to a heat exchanger, with the air cooled in the exchanger being sent to a check valve downstream of the heat exchanger and subsequently to a turbine, the valve being positioned so that air from a short-circuiting duct cannot return to the exchanger from the compressor.

An air gas separation plant comprising, in the direction of circulation of the air stream: a compression means that makes it possible to compress the air stream to a pressure P1 of between 1.15 bar abs and 2 bar abs, an adsorption unit of TSA type, and a cryogenic distillation unit, with the adsorption unit comprising at least two adsorbers A and B each having a parallelepipedal casing arranged horizontally and comprising: an air stream inlet and an air stream outlet, a fixed bed adsorbent mass, likewise of parallelepipedal shape, the faces of which are parallel to the faces of the casing; and a set of volumes allowing the air stream to pass through the adsorbent mass horizontally, over the entire cross-section and throughout the entire thickness thereof.