Air separation for coal gasification

Air separation units (ASUs) produce oxygen, nitrogen, argon and other rare gases from the air, the only raw material for ASUs. The process is normally powered by electricity.

Different air separation units are designed to produce cryogenic industrial gases. ASUs come in varying capacities: small, medium and large. ASUs are used mainly for steel, chemical, oil refining, petrochemical, glass, electronics and power production industries, as well as in gasification process.

ASU Capacity

Red Mountain Energy fully covers the range of ASUs needed for Coal Gasification by producing plants with a single capacity of 40000 – 60000 Nm³/hr.

The product line consists of ASUs with both external and internal compression.

The purity of separated products is as follows:

• Oxygen: up to 99,5…99,9%
• Nitrogen: up to 99,9995…99,9999%
• Argon: up to 99,9995%

The output can be delivered as gas and as liquid (liquefied gas). For gas production the oxygen output can be supplied at pressure close to atmospheric, or at higher pressure with internal compression.

ASUs can be adapted to a specific technological process according to the client’s requirements.

The ASU design is based on either low, medium or high pressure cycles. The dry circulating air is compressed with an efficient centrifugal compressor. The ASU is created on the basis of modern process and design decisions: front end air precooling, integrated air purification and drying in adsorbers using two layers (active alumina and zeolite), heat recuperation in highly efficient plate-fin heat exchangers, and cold production in turboexpander-boosters.

Improving efficiency in Coal Gasification

Red Mountain Energy recommends paying special attention to oxygen production:

• Oxygen is a critical component of Coal Gasification, therefore the reliability of the ASU will affect the reliability of the entire gasification plant.
• A stored quantity of back up liquid oxygen is capable of running the gasifiers for up to several hours and providing a smooth transition during unit warms-up and scheduled servicing.
• Careful consideration of the ASU compressors should be given when analyzing the units’ steam balance. Using electric pumps may be preferable if sufficient high-pressure steam will not be reliably available from the gasification process.
• A spare water chiller might provide additional reliability.
• A gasification plant can compensate some costs due to the integrated air separation process where it is possible to sell the by-products such as liquid nitrogen, argon and other rare gases.

Red Mountain Energy carries out the following work program based on EPC in regards to air separation:

• Engineering design
• Procurement
• Turn-key construction
• Plant maintenance
• Plant operation