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Air separation units

Premium Engineering offers a wide range of air separation units (ASUs), including small, medium and large capacity ASUs for various industries such as steel, oil and gas processing, refinery, the petrochemical industry, the chemical industry, the glass industry, electronics, power generation, as well as industrial gas retail. We offer the following ASUs for the production of nitrogen, oxygen, and argon as well as for complex air separation with extraction of rare gases (Ne, He, Kr, Xe).

The purity of air separation products is as follows:

    * nitrogen: up to 99.9995…99.9999% vol.;
    * oxygen: up to 99.5…99.9% vol.;
    * argon: up to 99.9995% vol.


The output can be delivered both as gas and as liquid (liquefied gas).

Why liquid output is necessary:

    * Process requirements. Many technologies are based on cryogenic processes which require the use of cryogenic liquids.
    * Backup systems. Backup systems are needed for storing and subsequent gasification of cryogenic liquids in case of irregular consumption, peak loads, or ASU shutdown.
    * Transportation and storage of industrial gases in a liquid state is commonly used in the trading of industrial gases.


Presently, there are three basic technologies of air separation:

    * adsorption separation
    * membrane separation
    * cryogenic separation


Adsorption air separation (pressure swing adsorption or PSA) processes rely on the fact that under pressure gases tend to be attracted to solid surfaces or "adsorbed". The higher the pressure, the more gas is adsorbed; when the pressure is reduced, the gas is released, or desorbed. PSA processes can be used to separate gases in a mixture because different gases tend to be attracted to different solid surfaces more or less strongly. For example, if a gas mixture such as air is passed under pressure through a vessel containing an adsorbent bed that attracts nitrogen more strongly than it does oxygen, part or all of the nitrogen will stay in the bed, and the gas coming out of the vessel will be enriched in oxygen. When the bed reaches the end of its capacity to adsorb nitrogen, it can be regenerated by reducing the pressure, thereby releasing the adsorbed nitrogen. It is then ready for another cycle of producing oxygen enriched air.

Membrane air separation is based on the principle that different gases have different permeation rates through the polymer film. Oxygen (plus water vapor and carbon dioxide) is considered a "fast gas" which diffuses more rapidly through the tube walls than the "slow gases," argon and nitrogen. This “fast gas/slow gas” diffusion allows dry air to be converted into a product that is an inert mix of mostly nitrogen gas and argon, and a low-pressure "permeate" or waste gas that is enriched in oxygen (plus water vapor and carbon dioxide) and vented from the shell.

Cryogenic air separation is a process by which highly purified gases or liquids are produced. This is achieved by taking large volumes of air from the atmosphere, which are then compressed, cooled, and liquefied. Through a process of distillation the air is then separated into its major components. After the air is compressed, impurities must be removed. Depending on user requirements, different variations can be used in cryogenic air separation cycles to produce industrial gas products.

The processing cycle depends on:

    * How many products are required (whether simply oxygen or nitrogen; both oxygen and nitrogen; or nitrogen and oxygen and argon).
    * Required purities of the products.
    * Gaseous product delivery pressures.
    * Whether the products need to be stored in liquid form.


In cryogenic gas processing various equipment is used such as distillation columns, heat exchangers, cold interconnecting piping etc. These operate at very low temperatures and therefore must be well insulated and located inside sealed "cold boxes". Cold boxes are tall structures with either a round or rectangular cross section. Depending on the plant type, size and capacity, cold boxes may have a height of 15 to 60 meters and 2 to 4 meters on each side.

Air separation units fall into three categories:

    * Cryogenic units
    * Adsorption units (PSA, VPSA)
    * Membrane units


Premium Engineering offers a wide model range of air separation units (ASUs) in all the three categories (cryogenic, adsorption, membrane) and guarantees reliable performance using the latest technology.

Quality, rules, and standards:we provide ISO 9001: 2000, ASME, compliance certificates and permits in the country of end-user for all our equipment.

Control system: Our air separation units (ASUs) are equipped with a PLC based control system providing on-line monitoring which in turn reduces the number of staff required and consequently reduces the risk of human error.

Materials and components: we use only high-quality and durable materials and top brand components in the fabrication of the equipment.

Design: Each air separation unit is delivered in a state of maximum assembly readiness, including a building block construction (BBC).The ASU is supplied in the form of integrated blocks and modules so as to save time and cost during installation. The compact design makes it ideal for field installation.

Testing : all our equipment undergoes full-scale factory testing carried out by the manufacturer. We can also conduct special tests according to the rules and standards of the country where the equipment is to be used. The customer is welcome to attend the testing process.

Service: our customers are offered a wide range of services including design, installation supervision and commissioning, personnel training, aftermarket service.