Turboexpander

An expander, also called gas relaxation or expansion turbine, is a gas turbine in the narrower sense, i.e. a turbine ( turbo-machine ), in which expanded a gas under pressure with removal of work.

An expander is different than a gas turbine, in a broader sense only from the actual turbine, not equipped with a compressor or a combustion chamber is an integral part of the machine. The gas to be expanded is therefore not generated by the machine itself, but falls from upstream processes to. In contrast to a simple choke is used by the expander, the energy of the gas.

The turbine can be one or more stages, axial or radial type. The discharged paper can be used to drive a generator, a compressor or a pump.

The expander is a subordination of the thermal fluid energy machines and thermal turbomachine (from Latin turbare = rotate ).

Components

The expander consists of principle

• A single-or multi-stage output shaft axial ( bladed steps) or radial (impellers ) Construction
• The guide stages ( vanes or diffusers )
• The outer housing.

The output may be due to in-going or at the outlet side shaft end.

(Temperature, composition ) are placed high demands on the materials used in terms of their strength, temperature stability and resistance even at the expander components against corrosion and oxidation due to the hot gas parameters similar to gas turbines. Therefore, there are primarily only high-alloy ferritic and austenitic steels and nickel-based alloys.

Areas of application

For processes processes in

• Coal and oil gasification plants
• Nitric acid and Terephthalsäureanlagen
• Fluid catalytic cracking ( FCC ) and residual catalytic cracking ( RCC ) systems
• Blast furnace gas plants
• Compressed air power plants

Either gases with high temperature and high pressure is generated and only partially "used up" or caused thereby.

The enthalpy contained in these hot gases can be converted into mechanical energy by expanding and is back as a useful mechanical energy to drive wT available.

The efficiency of the expander is higher, the higher is the inlet temperature of the gas and the pressure ratio of the turbine.

Manufacturer

General Electric, MAN Diesel & Turbo and Siemens Power Generation and Atlas Copco in Europe and Mitsubishi in Japan.

• Gas turbine