A method and apparatus for the production of air gases by the cryogenic separation of air with front end purification and air compression can include using an available compressed dry gas such as nitrogen, oxygen, stored purified air, or synthetic air to repressurize the adsorber without diverting any of the purified air just exiting the currently on-line adsorber or changing the flow rate of the main air compressor or air sent to the cold box. This enables the main air compressor (MAC) to operate at a relatively constant flow rate while also sending a relatively constant air flow to the cold box during this repressurization step, thereby reducing the risks of process upsets and minimizing capital expenditures related to the MAC and other warm-end equipments.

Disclosed in the present invention are a pressure equalizing system for air separation purification, and a control method. The system comprises: a first air main pipe; a pressurizing gas pipeline, which is connected to the first air main pipe and used for receiving a pressurizing gas and delivering same to the first air main pipe; and a control valve, located on the pressurizing gas pipeline, and having a degree of opening regulated by the flow regulator, thereby regulating an air intake amount of the pressurizing gas pipeline. The present invention solves the problem of an air separation rectification process being affected when dry nitrogen is used for pressure equalization of an adsorber; in the switching process of entering an adsorption stage from a regeneration stage, pressurizing dry nitrogen used in a pressure equalizing step previously mixes with damp air from a main air compressor before entering the adsorber, such that the gas components flowing towards an air separation cold box remain substantially unchanged, in order to reduce disturbance in conditions of gas entering a rectification column to take part in rectification due to a gas component gradually changing from dry nitrogen to dry air in the prior art, thus stabilizing the process conditions of the air separation cold box.

An air separation apparatus and process, which produces gaseous oxygen and/or nitrogen products at an elevated pressure through internal compression of respective liquid products, are disclosed. Split-core main heat exchangers are employed to warm up product streams generated in an air rectification unit against 1) a main feed air stream in the low-pressure heat exchanger and 2) at least one boosted pressure air stream in the high-pressure exchanger. Because the boosted pressure air stream is at a higher pressure and temperature than the main feed air stream, after separate heat exchange in the split main heat exchangers, the subsidiary waste nitrogen stream exiting the high-pressure heat exchanger is also warmer than the subsidiary waste nitrogen stream exiting the low-pressure heat exchanger. The warmer waste nitrogen stream is fed into the air purification unit for regeneration purposes and the cooler waste nitrogen stream is introduced into the nitrogen water tower to perform cooling duty. The two subsidiary waste nitrogen streams are also connected on the warm side of the main heat exchangers to allow flexible distribution of the flow.

A method and a device for producing an air product based on cryogenic rectification; after being cooled by a main heat exchanger, raw material air and nitrogen compressed by means of a compressor are sent to a rectification system for low temperature separation. In the rectification system, products such as oxygen and nitrogen are obtained by means of low temperature separation, and oxygen-enriched liquid air is obtained at or near the bottom of a rectification tower. The oxygen-enriched liquid air or liquid-state air in the rectification system is sent out after being raised to a target pressure by means of a low temperature liquid air pump; air products of various pressures can be produced by means of selecting low temperature liquid air pumps with different lifts or by connecting in series different amounts of low temperature liquid air pumps. The present method can avoid the need to arrange additional air compressors, entirely changing the method for producing medium and high pressure air products in a nitrogen circulation process, and importantly can reduce production costs significantly whilst having greater flexibility. In addition, the present method can increase the oxygen extraction rate of an apparatus, thereby improving the energy efficiency level.

Process and apparatus for the separation of a compressed feed air stream to produce an oxygen product using a distillation column having a lower-pressure column and a higher-pressure column, a higher-pressure heat exchanger and a lower-pressure heat exchanger where the gaseous nitrogen expander receives a nitrogen-enriched fraction from a position intermediate the warmer end and the colder end of the higher-pressure heat exchanger.

A method and apparatus for the production of air gases by the cryogenic separation of air with front end purification and air compression can include using an available compressed dry gas such as nitrogen, oxygen, stored purified air, or synthetic air to repressurize the adsorber without diverting any of the purified air just exiting the currently on-line adsorber or changing the flow rate of the main air compressor or air sent to the cold box. This enables the main air compressor (MAC) to operate at a relatively constant flow rate while also sending a relatively constant air flow to the cold box during this repressurization step, thereby reducing the risks of process upsets and minimizing capital expenditures related to the MAC and other warm-end equipments.

A method for producing liquefied natural gas and a stream of liquid nitrogen including step a): producing gaseous nitrogen in an air separation unit; step b): liquefying a stream of natural gas in a natural gas liquefaction unit including a main heat exchanger and a system for producing cold; step c): liquefying the nitrogen stream resulting from step a) in the main exchanger of the natural gas liquefaction unit in parallel with the liquefied natural gas in step b); wherein all the cold necessary for liquefying the stream of nitrogen and for liquefying the natural gas is supplied by the system for producing cold of the natural gas liquefaction unit.

A liquefier device which may be a retrofit to an air separation plant or utilized as part of a new design. The flow needed for the liquefier comes from an air separation plant running in a maxim oxygen state, in a stable mode. The three gas flows are low pressure oxygen, low pressure nitrogen, and higher pressure nitrogen. All of the flows are found on the side of the main heat exchanger with a temperature of about 37 degrees Fahrenheit. All of the gasses put into the liquefier come out as a subcooled liquid, for storage or return to the air separation plant. This new liquefier does not include a front end electrical compressor, and will take a self produced liquid nitrogen, pump it up to a runnable 420 psig pressure, and with the use of turbines, condensers, flash pots, and multi pass heat exchangers. The liquefier will make liquid from a planned amount of any pure gas oxygen or nitrogen an air separation plant can produce.

A system and method for producing an LNG product stream to provide fuel to generators, as an alternative to diesel, to power drilling and other equipment. Using sales gas from a natural gas/NGL plant containing less than 95% methane as a feed stream, production of LNG having 95% or more methane in quantities of 100,000 GPD or more LNG product are achievable with the system and method. The system and method preferably combine use of strategic heat exchange between the feed and a nitrogen-methane flash vapor stream and other streams within the LNG processing system without requiring heat exchange with process streams in the natural gas/NGL plant and a rectifier column that uses an internal knockback condenser and does not require a reboiler to remove heavier components from the sales gas feed.

A distillation column system and a plant are for production of oxygen by cryogenic fractionation of air. The distillation column system has a high-pressure column and a low-pressure column, a main condenser, and an argon column with an argon column top condenser. The low-pressure column comprises an upper mass transfer region, a lower mass transfer region and a middle mass transfer region. The argon column top condenser is arranged within the low-pressure column between the upper and middle mass transfer regions and is configured as a forced-flow evaporator.