Turboexpanders for Air Separation Units

To cool gases in the process cycle, expansion machines are used; they are the key equipment for reducing temperature in the technological cycle.
The operation of a turboexpander is based on expansion of the gas flow with extraction of external mechanical work.
The design is a centripetal turbine with a radial-axial impeller and a shaft equipped with one of several types of load devices for absorbing the external work: an oil brake, a blower stage, a compressor stage, or an electric generator.

In air separation units, a cryogenic cycle is implemented by means of a turboexpander in order to achieve low temperatures and subsequently liquefy the process air before it is fed into the rectification column of the cold box.

Principle of operation of a turboexpander

• Initial expansion of the flow occurs in the passages of the nozzle guide vanes, followed by further expansion in the impeller.
  The external work obtained on the expander wheel is transmitted to the unit shaft and then to a braking device, where this work is absorbed;
• During expansion of the flow, the working pressure decreases, and, as a result, its temperature is reduced.

Features of turboexpanders for ASUs

• Single-stage or multi-stage expander sections;
• Oil hydrodynamic or hydrostatic bearings;
• Load device in the form of a compressor stage;
• No contamination of the flow path with oil;
• Controllable parameters: flow rate and pressure;
• Unit power depends on pressure drop and flow rate;
• An automated protection system prevents emergency operating modes, including overspeed (“runaway”);
• High efficiency of the expander stage, improving the overall technical and economic performance of the ASU.

Turboexpander design work includes

• Thermodynamic calculation of the expander stage characteristics and determination of braking device characteristics;
• Determination of actual gas-dynamic parameters;
• Optimization of the combined operation of compressor and expander stages;
• Optimization of the unit’s flow path.

Production

Gas turboexpanders are manufactured at the cryogenic and compressor equipment plant of Hangzhou Oxygen Plant Group.

RusGazKrio LLC, which has more than fifteen years of experience working with this Chinese company, offers turboexpanders at manufacturer prices, suitable for:

• Air separation, refrigeration and helium units;
• Hydrogen liquefiers.

RusGazKrio successfully cooperates with Hangzhou Oxygen Plant Group, which develops and manufactures equipment for cold generation.
High-tech production lines and qualified personnel make it possible to solve complex tasks in the production of turboexpander units for liquefaction of air, nitrogen and natural gas over a wide range of operating conditions.

We offer installation, commissioning, service maintenance of the supplied equipment and other services as requested by the customer.